| 1. |
- Ah-King, Malin, 1973-, et al.
(författare)
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Sex in an Evolutionary Perspective : Just Another Reaction Norm
- 2010
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Ingår i: Evolutionary biology. - : Springer Science and Business Media LLC. - 0071-3260 .- 1934-2845. ; 37:4, s. 234-246
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Forskningsöversikt (refereegranskat)abstract
- It is common to refer to all sorts of clear-cut differences between the sexes as something that is biologically almost inevitable. Although this does not reflect the status of evolutionary theory on sex determination and sexual dimorphism, it is probably a common view among evolutionary biologists as well, because of the impact of sexual selection theory. To get away from thinking about biological sex and traits associated with a particular sex as something static, it should be recognized that in an evolutionary perspective sex can be viewed as a reaction norm, with sex attributes being phenotypically plastic. Sex determination itself is fundamentally plastic, even when it is termed “genetic”. The phenotypic expression of traits that are statistically associated with a particular sex always has a plastic component. This plasticity allows for much more variation in the expression of traits according to sex and more overlap between the sexes than is typically acknowledged. Here we review the variation and frequency of evolutionary changes in sex, sex determination and sex roles and conclude that sex in an evolutionary time-frame is extremely variable. We draw on recent findings in sex determination mechanisms, empirical findings of morphology and behaviour as well as genetic and developmental models to explore the concept of sex as a reaction norm. From this point of view, sexual differences are not expected to generally fall into neat, discrete, pre-determined classes. It is important to acknowledge this variability in order to increase objectivity in evolutionary research.
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| 2. |
- Andersson, Mathias H., 1976-
(författare)
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Man-made structures as habitat for marine faunal assemblages
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Artificial reefs are structures placed in the sea to promote marine life. Although constructions such as oil-rigs, wind farms, bridges and pier pilings are built for other purposes, they could be regarded as artificial reefs as they add new surfaces in the oceans, susceptible to colonization by marine organism. One of the most common constructions in the oceans is cylindrical structures of different materials. Most research of artificial reefs has been conducted in tropical and temperate water and experience and conclusions cannot always be applied to colder waters. Man-made constructions are common in northern European seas, however, few studies are presented in the scientific literature on their impact on the marine ecosystem. The aim of this thesis was to study cylindrical structures of different scale and materials, in order to determine their effect on local fish, algae and sessile invertebrate assemblages. These structures were offshore wind turbines, and pillars of different materials (concrete and steel), situated at the Swedish east and west coast, respectively. They add vertical surfaces into the otherwise empty water column, increasing the probability for fish and invertebrate larvae as well as algae spores and propagules to encounter these high structures, compared to low profile natural or other artificial reefs. Fish species usually associated with rocky reefs and algae communities, i.e. the two spotted goby and the goldsinny-wrasse, showed an increase in abundance around the introduced cylindrical structures. Similar effect on fish species were found on both the Swedish east and west coast. The observed increase in fish densities seemed to be caused by added habitat since the pillars and wind turbines provide shelter from predators as well as increased food availability. The latter was either due to the fouling assemblage or change in water movement. The environment created by the introduced structures functions both as nursery and spawning areas since juveniles, adults and gravid fish were recorded in close association with the structures. The fouling community on the vertical surfaces did not resemble the natural assemblages and a difference in recruitment and succession on the pillars of different materials were observed. Further, dissimilar fouling assemblages were observed with other species dominating the assemblages on a fifty year old light-house foundation compared to the seven year old wind turbines, both located in the same area. The sessile filter feeding invertebrates located on the foundations have an advantage in food accessibility towards individuals at the seabed, as the organisms on the foundations are constantly susceptible to the water passing by. In addition, by adding offshore structures in areas previously lacking hard surfaces, non-indigenous species could find new available habitat or the foundations can function as stepping stones into new geographical regions.
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| 3. |
- Andersson, Mathias H., 1976-
(författare)
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Offshore wind farms - ecological effects of noise and habitat alteration on fish
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There are large gaps in our understanding how fish populations are affected by the anthropogenic noise and the alteration of habitat caused by the construction and operation of offshore wind farms. These issues are of great importance as the construction of offshore wind farms will increase all over the world in the near future. This thesis studies these effects with a focus on fish. The wind turbine foundations function as artificial reefs and are colonized by invertebrates, algae and fish. The epibenthic assemblages are influenced by factors such as hydrographical parameters, time of submergence, distance to natural hard bottom, material and texture (PAPER I, II). Once an epibenthic assemblage has been developed, fish utilize it for different ecosystem services such as food, shelter, and spawning and nursery area. Benthic and semi-pelagic species show a stronger response to the introduced foundation than pelagic species, as it is the bottom habitat that has mainly been altered (PAPER I, II). Pelagic species could be positively affected by the increased food availability - but it takes time and the effect is local. Construction noise like pile driving creates high levels of sound pressure and acoustic particle motion in the water and seabed. This noise induces behavioural reactions in cod (Gadus morhua) and sole (Solea solea). These reactions could occur up to tens of kilometres distance from the source (PAPER III). During power production, the wind turbines generate a broadband noise with a few dominating tones (PAPER IV, V), which are detectable by sound pressure sensitive fish at a distance of several kilometres even though intense shipping occurs in the area. Motion sensitive species will only detect the turbine noise at around a ten meter distance. Sound levels are only high enough to possibly cause a behavioural reaction within meters from a turbine (PAPER IV, V).
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| 4. |
- Anrup, Roland, et al.
(författare)
-
Centrala universitetsvärden hotas av bolagiseringsidén
- 2013
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Ingår i: Dagens nyheter. - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Högskolestiftelser. Förslaget att driva svenska universitet i stiftelseform öppnar för bolagisering. Men det är ingen riktig utredning, utan en politisk pamflett utan eftertanke. Privatisering av universitet hotar både oberoendet, forskningskvaliteten och samhällsnyttan, skriver 36 forskare vid svenska högskolor och universitet.
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| 5. |
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| 6. |
- Audusseau, Hélène, 1986-
(författare)
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Effect of climate and land use on niche utilization and distribution of nettle-feeding butterflies
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Anthropogenic changes in climate and land use are causing a dramatic erosion of biodiversity. To understand this erosion, and predict future transformations of biodiversity, we need to understand better species’ response to these changes at different spatial and temporal scales. Modeling studies have identified correlations between physical parameters of the environment and species’ distribution at large spatial scales. However, this does not accurately characterize the response of a specific species, since this does not account for the constraints arising from the biology of the species. This thesis shall combine knowledge on the biology of species obtained from laboratory experiments with modeling studies. This will allow us (i) to identify life history traits and biotic interactions that influence species’ adaptive potential, and hence, explain possible differences in species’ distribution, and (ii) to consider, not only the ecological but also the evolutionary aspects of species’ response to changes. This integrative approach is likely to improve our predictions on species’ population dynamic in a changing environment.I focus on a community of butterflies in Sweden (Vanessa cardui, Polygonia c-album, Aglais urticae, Aglais io, Araschnia levana) that feeds on the stinging nettle (Urtica dioica). The available knowledge on the biology of these species and their short life cycles, which allow investigations of their response to changes on a short-time scale, make them a good system to study. Among three of these species, I showed great differences in organisms’ response to variation in food nutrient content. This is a potentially important finding considering the increased use of chemical fertilizers. These differences are to a large extent explained by differences among species in their degree of host plant specialization and voltinism (paper II). Thus, life history traits determine the response of species to environmental changes, but are themselves likely to evolve in response to such changes. Climate change, for instance, may alter the phenological synchrony between plant-feeding insects and their host plants, making it necessary for the insects to evolve their host plant range in order to ensure the availability of resources during larval development (paper I & III). The biology of a species, including biotic interactions, helps to explain the observed shift in a species’ distribution and environmental niche that result from climate change. I have shown that the recent establishment of A. levana in southern Sweden has modified the niche of the resident species, A. urticae and A. io (Paper IV). Niche partitioning in this community is likely mediated by parasite-driven apparent competition.
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| 7. |
- Audusseau, Helene, et al.
(författare)
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Implications of a temperature increase for host plant range : predictions for a butterfly
- 2013
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 3:9, s. 3021-3029
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Tidskriftsartikel (refereegranskat)abstract
- Although changes in phenology and species associations are relatively well-documented responses to global warming, the potential interactions between these phenomena are less well understood. In this study, we investigate the interactions between temperature, phenology (in terms of seasonal timing of larval growth) and host plant use in the polyphagous butterfly Polygonia c-album. We found that the hierarchy of larval performance on three natural host plants was not modified by a temperature increase as such. However, larval performance on each host plant and temperature treatment was affected by rearing season. Even though larvae performed better at the higher temperature regardless of the time of the rearing, relative differences between host plants changed with the season. For larvae reared late in the season, performance was always better on the herbaceous plant than on the woody plants. In this species, it is likely that a prolonged warming will lead to a shift from univoltinism to bivoltinism. The demonstrated interaction between host plant suitability and season means that such a shift is likely to lead to a shift in selective regime, favoring specialization on the herbaceous host. Based on our result, we suggest that host range evolution in response to temperature increase would in this species be highly contingent on whether the population undergoes a predicted shift from one to two generations. We discuss the effect of global warming on species associations and the outcome of asynchrony in rates of phenological change.
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| 8. |
- Audusseau, Hélène, et al.
(författare)
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Species range expansion constrains the ecological niches of resident butterflies
- 2017
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 44:1, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Changes in community composition resulting from environmental changes modify biotic interactions and affect the distribution and density of local populations. Such changes are currently occurring in nettle-feeding butterflies in Sweden where Araschnia levana has recently expanded its range northward and is now likely to interact with resident species (Aglais urticae and Aglais io). Butterfly occurrence data collected over years and across regions enabled us to investigate how a recent range expansion of A. levana may have affected the environmental niche of resident species.Location: We focused on two regions of Sweden (Skane and Norrstrom) where A. levana has and has not established and two time periods (2001-2006 and 2009-2012) during its establishment in Skane.Methods: We performed two distinct analyses in each region using the PCA-env and the framework described in Broennimann etal. (2012). First, we described the main sources of variation in the environment. Second, in each time period and region, we characterized the realized niches of our focal species across topographic and land use gradients. Third, we quantified overlaps and differences in realized niches between and within species over time.Results: In Skane, A. levana has stabilized its distribution over time, while the distribution of the native species has shifted. These shifts depicted a consistent pattern of avoiding overlap between the native species and the environmental space occupied by A. levana, and it was stronger for A. urticae than for A. io. In both regions, we also found evidence of niche partitioning between native species.Main conclusions: Interspecific interactions are likely to affect local species distributions. It appears that the ongoing establishment of A. levana has modified local biotic interactions and induced shifts in resident species distributions. Among the mechanisms that can explain such patterns of niche partitioning, parasitoid-driven apparent competition may play an important role in this community.
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| 9. |
- Audusseau, Hélène, et al.
(författare)
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Why stay in a bad relationship? The effect of local host phenology on a generalist butterfly feeding on a low-ranked host
- 2016
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: In plant-feeding insects, the evolutionary retention of polyphagy remains puzzling. A better understanding of the relationship between these organisms and changes in the metabolome of their host plants is likely to suggest functional links between them, and may provide insights into how polyphagy is maintained. Results: We investigated the phenological change of Cynoglossum officinale, and how a generalist butterfly species, Vanessa cardui, responded to this change. We used untargeted metabolite profiling to map plant seasonal changes in both primary and secondary metabolites. We compared these data to differences in larval performance on vegetative plants early and late in the season. We also performed two oviposition preference experiments to test females' ability to choose between plant developmental stages (vegetative and reproductive) early and late in the season. We found clear seasonal changes in plant primary and secondary metabolites that correlated with larval performance. The seasonal change in plant metabolome reflected changes in both nutrition and toxicity and resulted in zero survival in the late period. However, large differences among families in larval ability to feed on C. officinale suggest that there is genetic variation for performance on this host. Moreover, females accepted all plants for oviposition, and were not able to discriminate between plant developmental stages, in spite of the observed overall differences in metabolite profile potentially associated with differences in suitability as larval food. Conclusions: In V. cardui, migratory behavior, and thus larval feeding times, are not synchronized with plant phenology at the reproductive site. This lack of synchronization, coupled with the observed lack of discriminatory oviposition, obviously has potential fitness costs. However, this opportunistic behavior may as well function as a source of potential host plant evolution, promoting for example the acceptance of new plants.
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| 10. |
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| 11. |
- Bergström, Anders, 1969-
(författare)
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Oviposition strategies in butterflies and consequences for conservation
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oviposition strategies are an important component of life history evolution in insects. Oviposition is a complex behaviour, where females must locate suitable habitat patches, locate oviposition sites, evaluate the quality, and finally decide how many eggs to lay. In this thesis, I explore some factors that may influence oviposition strategies in female butterflies. It discusses oviposition strategies from large to fine scales and ends with a discussion on implications for conservation. In paper I we tested for local adaptations in oviposition preference and larval performance in Polyommatus icarus. The result suggests that this species is evolutionary conservative in its utilization of the tested host plants. In the second paper we investigated frequency-dependent host plant choice in Polygonia c-album and showed that females spent significantly more time, and laid more eggs, in patches with high frequency of the preferred host. The influence of nectar sources on host plant choice in P. icarus was tested in paper III, females preferred ovipositing on host plants with flowers and after feeding. In paper IV we investigated oviposition “mistakes” in P. c-album and found differences in discrimination of hosts and non-hosts. Further, we showed that P. c-album butterflies are capable of responding to host quality by increasing clutch sizes on a high ranked host (paper V). Finally, in paper VI I explored how female oviposition behaviour can influence habitat management for a threatened butterfly species, Parnassius mnemosyne, by doing an observational field study on oviposition site preferences. This thesis highlights oviposition as a stepwise process and show that female discrimination is important at a multitude of levels with implications for oviposition strategies.
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| 12. |
- Bergström, Anders, et al.
(författare)
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Putting more eggs in the best basket : clutch size regulation in the comma butterfly
- 2006
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 31:3, s. 255-260
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Tidskriftsartikel (refereegranskat)abstract
- 1. Many studies have identified different factors influencing clutchsize regulation, primarily within various groups of insects. One prediction is that ovipositing females should increase clutch size with host quality. However, in many studies it is not clear whether ovipositing females are responding to host quality or quantity. 2. Females of the polyphagous comma butterfly, allowed to oviposit on two hosts differing greatly in quality: the preferred host, stinging nettle (Polygonia c-album (L.), wereUrtica dioica L.), and the low-ranked host, birch (Betula pubescens Ehrh). Ovipositing females were observed visually and clutch sizes were recorded. The experiment was repeated in three different years; in total, 938 observations of oviposition events were made. 3. In all three years, females ovipositing on (median 1.6–1.85) compared with females ovipositing on 1.0–1.3) three years were pooled. 4. Thus, on better hosts. It is suggested that the proximate mechanism is likely to be a response to the same stimuli used for female ranking of host plants in the preference hierarchy. U. dioica laid larger clutchesB. pubescens (median. The difference was significant in two out of three years and when allP. c-album females exhibit clutch-size regulation, with larger clutches
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| 13. |
- Blanckenhorn, Wolf U, et al.
(författare)
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Proximate causes of Rensch's rule : Does sexual size dimorphism in arthropods result from sex differences in development time?
- 2007
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Ingår i: American Naturalist. ; 169:2, s. 245-257
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Tidskriftsartikel (refereegranskat)abstract
- A prominent interspecific pattern of sexual size dimorphism (SSD) is Rensch's rule, according to which male body size is more variable or evolutionarily divergent than female body size. Assuming equal growth rates of males and females, SSD would be entirely mediated, and Rensch's rule proximately caused, by sexual differences in development times, or sexual bimaturism (SBM), with the larger sex developing for a proportionately longer time. Only a subset of the seven arthropod groups investigated in this study exhibits Rensch's rule. Furthermore, we found only a weak positive relationship between SSD and SBM overall, suggesting that growth rate differences between the sexes are more important than development time differences in proximately mediating SSD in a wide but by no means comprehensive range of arthropod taxa. Except when protandry is of selective advantage ( as in many butterflies, Hymenoptera, and spiders), male development time was equal to ( in water striders and beetles) or even longer than ( in drosophilid and sepsid flies) that of females. Because all taxa show female-biased SSD, this implies faster growth of females in general, a pattern markedly different from that of primates and birds (analyzed here for comparison). We discuss three potential explanations for this pattern based on life-history trade-offs and sexual selection.
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| 14. |
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| 15. |
- Braga, Mariana P., et al.
(författare)
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Bayesian Inference of Ancestral Host-Parasite Interactions under a Phylogenetic Model of Host Repertoire Evolution
- 2020
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Ingår i: Systematic Biology. - : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 69:6, s. 1149-1162
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Tidskriftsartikel (refereegranskat)abstract
- Intimate ecological interactions, such as those between parasites and their hosts, may persist over long time spans, coupling the evolutionary histories of the lineages involved. Most methods that reconstruct the coevolutionary history of such interactions make the simplifying assumption that parasites have a single host. Many methods also focus on congruence between host and parasite phylogenies, using cospeciation as the null model. However, there is an increasing body of evidence suggesting that the host ranges of parasites are more complex: that host ranges often include more than one host and evolve via gains and losses of hosts rather than through cospeciation alone. Here, we develop a Bayesian approach for inferring coevolutionary history based on a model accommodating these complexities. Specifically, a parasite is assumed to have a host repertoire, which includes both potential hosts and one or more actual hosts. Over time, potential hosts can be added or lost, and potential hosts can develop into actual hosts or vice versa. Thus, host colonization is modeled as a two-step process that may potentially be influenced by host relatedness. We first explore the statistical behavior of our model by simulating evolution of host-parasite interactions under a range of parameter values. We then use our approach, implemented in the program RevBayes, to infer the coevolutionary history between 34 Nymphalini butterfly species and 25 angiosperm families. Our analysis suggests that host relatedness among angiosperm families influences how easily Nymphalini lineages gain new hosts.
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| 16. |
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| 17. |
- Braga, Mariana Pires, 1988-
(författare)
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Evolution of host repertoires and the diversification of butterflies
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- All herbivorous insects are specialized to some extent to their host plants, but the level of specialization varies greatly. Insect-plant coevolution is often invoked to explain the large diversity of herbivorous insects, but the role of specialization during diversification is still controversial. Although well-studied, our understanding of the evolution of species interactions is still improving, and recent theoretical developments have highlighted the role of generalization (via colonization of new hosts) on diversification. In this thesis, various approaches are combined for a detailed study of the origins of macroevolutionary patterns of host use and butterfly diversity. Chapter I provides a mechanistic basis for such patterns through simulations of lineages evolved in silico. By separating the effects of the number of hosts used by a parasite lineage and the diversity of resources they encompass, we found that resource diversity, rather than host range per se, was the main driver of parasite species richness in both simulated and empirical systems. In Chapter II, we combined network and phylogenetic analyses to quantify support for the two main hypothesized drivers of diversification of herbivorous insects. Based on analyses of two butterfly families, Nymphalidae and Pieridae, we found that variability in host use is essential for diversification, while radiation following the colonization of a new host is rare but can produce high diversity. We then reconciled the two alternative hypotheses into a unified process of host-associated diversification where continuous probing of new hosts and retention of the ability to use hosts colonized in the past are the main factors shaping butterfly-plant networks. While network analysis is a powerful tool for investigating patterns of interaction, other methods are necessary to directly test the mechanisms generating the observed patterns. Therefore, in Chapter III we describe a model of host repertoire evolution we developed for Bayesian inference of evolution of host-parasite interactions. The approach was validated with both simulated and empirical data sets. Finally, in Chapter IV we used the method described in Chapter III to explicitly test the predictions made in Chapter II about the evolution of butterfly-plant networks. We found direct evidence for the role of expansion of fundamental host repertoire and phylogenetic conservatism as important drivers of host repertoire evolution. Thus, using three different approaches, we found overall support for the idea that variation in host use accumulated over evolutionary time is essential for butterfly diversification.
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| 18. |
- Braga, Mariana P., et al.
(författare)
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Host use dynamics in a heterogeneous fitness landscape generates oscillations in host range and diversification
- 2018
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 72:9, s. 1773-1783
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Tidskriftsartikel (refereegranskat)abstract
- Colonization of novel hosts is thought to play an important role in parasite diversification, yet little consensus has been achieved about the macroevolutionary consequences of changes in host use. Here, we offer a mechanistic basis for the origins of parasite diversity by simulating lineages evolved in silico. We describe an individual-based model in which (i) parasites undergo sexual reproduction limited by genetic proximity, (ii) hosts are uniformly distributed along a one-dimensional resource gradient, and (iii) host use is determined by the interaction between the phenotype of the parasite and a heterogeneous fitness landscape. We found two main effects of host use on the evolution of a parasite lineage. First, the colonization of a novel host allowed parasites to explore new areas of the resource space, increasing phenotypic and genotypic variation. Second, hosts produced heterogeneity in the parasite fitness landscape, which led to reproductive isolation and therefore, speciation. As a validation of the model, we analyzed empirical data from Nymphalidae butterflies and their host plants. We then assessed the number of hosts used by parasite lineages and the diversity of resources they encompass. In both simulated and empirical systems, host diversity emerged as the main predictor of parasite species richness.
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| 19. |
- Braga, Mariana P., et al.
(författare)
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Phylogenetic reconstruction of ancestral ecological networks through time for pierid butterflies and their host plants
- 2021
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 24:10, s. 2134-2145
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Tidskriftsartikel (refereegranskat)abstract
- The study of herbivorous insects underpins much of the theory that concerns the evolution of species interactions. In particular, Pieridae butterflies and their host plants have served as a model system for studying evolutionary arms races. To learn more about the coevolution of these two clades, we reconstructed ancestral ecological networks using stochastic mappings that were generated by a phylogenetic model of host-repertoire evolution. We then measured if, when, and how two ecologically important structural features of the ancestral networks (modularity and nestedness) evolved over time. Our study shows that as pierids gained new hosts and formed new modules, a subset of them retained or recolonised the ancestral host(s), preserving connectivity to the original modules. Together, host-range expansions and recolonisations promoted a phase transition in network structure. Our results demonstrate the power of combining network analysis with Bayesian inference of host-repertoire evolution to understand changes in complex species interactions over time.
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| 20. |
- Braga, Mariana P., et al.
(författare)
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Unifying host-associated diversification processes using butterfly-plant networks
- 2018
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Explaining the exceptional diversity of herbivorous insects is an old problem in evolutionary ecology. Here we focus on the two prominent hypothesised drivers of their diversification, radiations after major host switch or variability in host use due to continuous probing of new hosts. Unfortunately, current methods cannot distinguish between these hypotheses, causing controversy in the literature. Here we present an approach combining network and phylogenetic analyses, which directly quantifies support for these opposing hypotheses. After demonstrating that each hypothesis produces divergent network structures, we then investigate the contribution of each to diversification in two butterfly families: Pieridae and Nymphalidae. Overall, we find that variability in host use is essential for butterfly diversification, while radiations following colonisation of a new host are rare but can produce high diversity. Beyond providing an important reconciliation of alternative hypotheses for butterfly diversification, our approach has potential to test many other hypotheses in evolutionary biology.
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| 21. |
- Cassel, Anna, et al.
(författare)
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Effects of population size and food stress on fitness-related characters in the scarce heath, a rare butterfly in Western Europe
- 2001
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Ingår i: Conservation Biology. - : Blackwell Science Publishing. - 0888-8892 .- 1523-1739. ; 15:6, s. 1667-1673
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: Knowledge about the effects of inbreeding in natural populations is scarce, especially in invertebrates. We analyzed to what extent fitness-related traits in the scarce heath ( Coenonympha hero), a butterfly, are affected by population size and isolation and whether differences in food quality influence these effects. We categorized nine populations as either large or small and isolated. Full-sib groups of offspring from 27 females were followed under seminatural conditions. Because of increased zygote mortality, egg hatchability was significantly lower in the small and isolated populations than in the large ones. Population category had no effect on larval weight under optimal conditions, but weight was significantly lower in the small-isolated category with low food quality. The effects of inbreeding can thus be hidden when conditions are benign but can appear under stress. Survival also differed significantly between population categories, and larval developmental time tended to be longer in the small-isolated category, irrespective of food conditions. We suggest that the differences in fitness between offspring from large and small isolated populations are at least partly due to inbreeding. This adds a further threat to a species that is already suffering from decreasing population sizes and increasing isolation among populations.
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| 22. |
- Celorio-Mancera, Maria de la Paz, et al.
(författare)
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Chromosome Level Assembly of the Comma Butterfly (Polygonia c-album)
- 2021
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Ingår i: Genome Biology and Evolution. - : Oxford University Press (OUP). - 1759-6653 .- 1759-6653. ; 13:5
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Tidskriftsartikel (refereegranskat)abstract
- The comma butterfly (Polygonia c-album, Nymphalidae, Lepidoptera) is a model insect species, most notably in the study of phenotypic plasticity and plant-insect coevolutionary interactions. In order to facilitate the integration of genomic tools with a diverse body of ecological and evolutionary research, we assembled the genome of a Swedish comma using 10X sequencing, scaffolding with matepair data, genome polishing, and assignment to linkage groups using a high-density linkage map. The resulting genome is 373 Mb in size, with a scaffold N50 of 11.7 Mb and contig N50 of 11,2Mb. The genome contained 90.1% of single-copy Lepidopteran orthologs in a BUSCO analysis of 5,286 genes. A total of 21,004 gene-models were annotated on the genome using RNA-Seq data from larval and adult tissue in combination with proteins from the Arthropoda database, resulting in a high-quality annotation for which functional annotations were generated. We further documented the quality of the chromosomal assembly via synteny assessment with Melitaea cinxia. The resulting annotated, chromosome-level genome will provide an important resource for investigating coevolutionary dynamics and comparative analyses in Lepidoptera.
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| 23. |
- Celorio-Mancera, Maria de la Paz, et al.
(författare)
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Mechanisms of macroevolution : polyphagous plasticity in butterfly larvae revealed by RNA-Seq
- 2013
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 22:19, s. 4884-4895
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Tidskriftsartikel (refereegranskat)abstract
- Transcriptome studies of insect herbivory are still rare, yet studies in model systems have uncovered patterns of transcript regulation that appear to provide insights into how insect herbivores attain polyphagy, such as a general increase in expression breadth and regulation of ribosomal, digestion- and detoxification-related genes. We investigated the potential generality of these emerging patterns, in the Swedish comma, Polygonia c-album, which is a polyphagous, widely-distributed butterfly. Urtica dioica and Ribes uva-crispa are hosts of P. c-album, but Ribes represents a recent evolutionary shift onto a very divergent host. Utilizing the assembled transcriptome for read mapping, we assessed gene expression finding that caterpillar life-history (i.e. 2nd vs. 4th-instar regulation) had a limited influence on gene expression plasticity. In contrast, differential expression in response to host-plant identified genes encoding serine-type endopeptidases, membrane-associated proteins and transporters. Differential regulation of genes involved in nucleic acid binding was also observed suggesting that polyphagy involves large scale transcriptional changes. Additionally, transcripts coding for structural constituents of the cuticle were differentially expressed in caterpillars in response to their diet indicating that the insect cuticle may be a target for plant defence. Our results state that emerging patterns of transcript regulation from model species appear relevant in species when placed in an evolutionary context.
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| 24. |
- Chazot, Nicolas, et al.
(författare)
-
Conserved ancestral tropical niche but different continental histories explain the latitudinal diversity gradient in brush-footed butterflies
- 2021
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- The global increase in species richness toward the tropics across continents and taxonomic groups, referred to as the latitudinal diversity gradient, stimulated the formulation of many hypotheses to explain the underlying mechanisms of this pattern. We evaluate several of these hypotheses to explain spatial diversity patterns in a butterfly family, the Nymphalidae, by assessing the contributions of speciation, extinction, and dispersal, and also the extent to which these processes differ among regions at the same latitude. We generate a time-calibrated phylogeny containing 2,866 nymphalid species (~45% of extant diversity). Neither speciation nor extinction rate variations consistently explain the latitudinal diversity gradient among regions because temporal diversification dynamics differ greatly across longitude. The Neotropical diversity results from low extinction rates, not high speciation rates, and biotic interchanges with other regions are rare. Southeast Asia is also characterized by a low speciation rate but, unlike the Neotropics, is the main source of dispersal events through time. Our results suggest that global climate change throughout the Cenozoic, combined with tropical niche conservatism, played a major role in generating the modern latitudinal diversity gradient of nymphalid butterflies.
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| 25. |
- Dalin, Peter, et al.
(författare)
-
Host-plant quality adaptively affects the diapause threshold : evidence from leaf beetles in willow plantations
- 2012
-
Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 37:6, s. 490-499
-
Tidskriftsartikel (refereegranskat)abstract
- 1. Voltinism of herbivorous insects can vary depending on environmental conditions. The leaf beetle Phratora vulgatissima L. is univoltine in Sweden but will sometimes initiate a second generation in short-rotation coppice (SRC) willow plantations. 2. The study investigated whether increased voltinism by P. vulgatissima in plantations can be explained by (i) rapid life-cycle development allowing two generations, or (ii) postponed diapause induction on coppiced willows. 3. In the field, no difference was found in the phenology or development of first-generation broods between plantations (S. viminalis) and natural willow habitats (S. cinerea). However, the induction of diapause occurred 12 weeks later in SRC willow plantations. 4. Laboratory experiments indicated no genetic difference in the critical day-length for diapause induction between beetles originating from plantations and natural habitats. Development time was unaffected by host-plant quality but critical day-length was prolonged by almost an hour when the beetles were reared on a non-preferred willow species (S. phylicifolia). When reared on new leaves from re-sprouting shoots of recently coppiced willow plants, diapause incidence was significantly less than when the beetles were reared on mature leaves from uncoppiced plants. 5. The study suggests that P. vulgatissima has a plastic diapause threshold influenced by host-plant quality. The use of host-plant quality as a diapause-inducing stimulus is likely to be adaptive in cases where food resources are unpredictable, such as when new host-plant tissue is produced after a disturbance. SRC willows may allow two beetle generations due to longer growing seasons of coppiced plants that grow vigorously.
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| 26. |
- de la Paz Celorio-Mancera, Maria, 1978-, et al.
(författare)
-
Evolutionary history of host use, rather than plant phylogeny, determines gene expression in a generalist butterfly
- 2016
-
Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 16
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Although most insect species are specialized on one or few groups of plants, there are phytophagous insects that seem to use virtually any kind of plant as food. Understanding the nature of this ability to feed on a wide repertoire of plants is crucial for the control of pest species and for the elucidation of the macroevolutionary mechanisms of speciation and diversification of insect herbivores. Here we studied Vanessa cardui, the species with the widest diet breadth among butterflies and a potential insect pest, by comparing tissue-specific transcriptomes from caterpillars that were reared on different host plants. We tested whether the similarities of gene-expression response reflect the evolutionary history of adaptation to these plants in the Vanessa and related genera, against the null hypothesis of transcriptional profiles reflecting plant phylogenetic relatedness. Result: Using both unsupervised and supervised methods of data analysis, we found that the tissue-specific patterns of caterpillar gene expression are better explained by the evolutionary history of adaptation of the insects to the plants than by plant phylogeny. Conclusion: Our findings suggest that V. cardui may use two sets of expressed genes to achieve polyphagy, one associated with the ancestral capability to consume Rosids and Asterids, and another allowing the caterpillar to incorporate a wide range of novel host-plants.
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| 27. |
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| 28. |
- Eriksson, Maertha, et al.
(författare)
-
Insect brain plasticity : effects of olfactory input on neuropil size
- 2019
-
Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 6:8
-
Tidskriftsartikel (refereegranskat)abstract
- Insect brains are known to express a high degree of experience-dependent structural plasticity. One brain structure in particular, the mushroom body (MB), has been attended to in numerous studies as it is implicated in complex cognitive processes such as olfactory learning and memory. It is, however, poorly understood to what extent sensory input per se affects the plasticity of the mushroom bodies. By performing unilateral blocking of olfactory input on immobilized butterflies, we were able to measure the effect of passive sensory input on the volumes of antennal lobes (ALs) and MB calyces. We showed that the primary and secondary olfactory neuropils respond in different ways to olfactory input. ALs show absolute experience-dependency and increase in volume only if receiving direct olfactory input from ipsilateral antennae, while MB calyx volumes were unaffected by the treatment and instead show absolute age-dependency in this regard. We therefore propose that cognitive processes related to behavioural expressions are needed in order for the calyx to show experience-dependent volumetric expansions. Our results indicate that such experience-dependent volumetric expansions of calyces observed in other studies may have been caused by cognitive processes rather than by sensory input, bringing some causative clarity to a complex neural phenomenon.
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| 29. |
- Eriksson, Maertha, et al.
(författare)
-
Structural plasticity of olfactory neuropils in relation to insect diapause
- 2020
-
Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 10:24, s. 14423-14434
-
Tidskriftsartikel (refereegranskat)abstract
- Many insects that live in temperate zones spend the cold season in a state of dormancy, referred to as diapause. As the insect must rely on resources that were gathered before entering diapause, keeping a low metabolic rate is of utmost importance. Organs that are metabolically expensive to maintain, such as the brain, can therefore become a liability to survival if they are too large. Insects that go through diapause as adults generally do so before entering the season of reproduction. This order of events introduces a conflict between maintaining low metabolism during dormancy and emerging afterward with highly developed sensory systems that improve fitness during the mating season. We investigated the timing of when investments into the olfactory system are made by measuring the volumes of primary and secondary olfactory neuropils in the brain as they fluctuate in size throughout the extended diapause life-period of adult Polygonia c-album butterflies. Relative volumes of both olfactory neuropils increase significantly during early adult development, indicating the importance of olfaction to this species, but still remain considerably smaller than those of nondiapausing conspecifics. However, despite butterflies being kept under the same conditions as before the dormancy, their olfactory neuropil volumes decreased significantly during the postdormancy period. The opposing directions of change in relative neuropil volumes before and after diapause dormancy indicate that the investment strategies governing structural plasticity during the two life stages could be functionally distinct. As butterflies were kept in stimulus-poor conditions, we find it likely that investments into these brain regions rely on experience-expectant processes before diapause and experience-dependent processes after diapause conditions are broken. As the shift in investment strategies coincides with a hard shift from premating season to mating season, we argue that these developmental characteristics could be adaptations that mitigate the trade-off between dormancy survival and reproductive fitness.
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| 30. |
- Esperk, Toomas, et al.
(författare)
-
Achieving high sexual dimorphism : insects add instars
- 2007
-
Ingår i: Ecological Entomology. ; 32, s. 243-256
-
Tidskriftsartikel (refereegranskat)abstract
- 1. In arthropods, the evolution of sexual size dimorphism (SSD) may be constrained by a physiological limit on growth within each particular larval instar. A high SSD could, however, be attained if the larvae of the larger sex pass through a higher number of larval instars.2. Based on a survey of published case studies, the present review shows that sex-related difference in the number of instars is a widespread phenomenon among insects. In the great majority of species with a sexually dimorphic instar number, females develop through a higher number of instars than males.3. Female-biased sexual dimorphism in final sizes in species with sexually dimorphic instar number was found to considerably exceed a previously estimated median value of SSD for insects in general. This suggests a causal connection between high female-biased SSD, and additional instars in females. Adding an extra instar to larval development allows an insect to increase its adult size at the expense of prolonged larval development.4. As in the case of additional instars, SSD is fully formed late in ontogeny, larval growth schedules and imaginal sizes can be optimised independently. No conflict between selective pressures operating in juvenile and adult stages is therefore expected.5. In most species considered, the number of instars also varied within the sexes. Phenotypic plasticity in instar number may thus be a precondition for a sexual difference in instar number to evolve.
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| 31. |
- Esperk, Toomas, et al.
(författare)
-
Intraspecific variability in the number of larval instars in insects
- 2007
-
Ingår i: J. Economic Entomology. ; 100, s. 627-646
-
Tidskriftsartikel (refereegranskat)abstract
- The number of larval instars varies widely across insect species. Although in star number is frequently considered to be invariable within species, intraspecific variability in the number of instars is not an exceptional phenomenon. However, the knowledge has remained fragmentary, and there are no recent attempts to synthesize the results of relevant studies. Based on published case studies, we show that intraspecific variability in the number of larval instars is widespread across insect taxa, occurring in most major orders, in both hemimetabolous and holometabolous insects. We give an overview of various factors that have been observed to affect the number of instars. Temperature, photoperiod, food quality and quantity, humidity, rearing density, physical condition, inheritance, and sex are the most common factors influencing the number of instars. We discuss adaptive scenarios that may provide ultimate explanations for the plasticity in instar number. The data available largely support the compensation scenario, according to which instar number increases in adverse conditions when larvae fail to reach a species-specific threshold size for metamorphosis. However, in Orthoptera and Coleoptera, there are some exceptional species in which instar number is higher in favorable conditions. In more specific cases, the adaptive value of the variability in instar number may be in reaching or maintaining the developmental stage adapted to hibernation, producing additional generations in multivoltine species, or increasing the probability of surviving in long-lasting adverse conditions.
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| 32. |
- Gamberale-Stille, Gabriella, et al.
(författare)
-
Host plant choice in the comma butterfly-larval choosiness may ameliorate effects of indiscriminate oviposition
- 2014
-
Ingår i: Insect Science. - : Wiley. - 1672-9609 .- 1744-7917. ; 21:4, s. 499-506
-
Tidskriftsartikel (refereegranskat)abstract
- In most phytophagous insects, the larval diet strongly affects future fitness and in species that do not feed on plant parts as adults, larval diet is the main source of nitrogen. In many of these insect host plant systems, the immature larvae are considered to be fully dependent on the choice of the mothers, who, in turn, possess a highly developed host recognition system. This circumstance allows for a potential mother-offspring conflict, resulting in the female maximizing her fecundity at the expense of larval performance on suboptimal hosts. In two experiments, we aimed to investigate this relationship in the polyphagous comma butterfly, Polygonia c-album, by comparing the relative acceptance of low- and medium-ranked hosts between females and neonate larvae both within individuals between life stages, and between mothers and their offspring. The study shows a variation between females in oviposition acceptance of low-ranked hosts, and that the degree of acceptance in the mothers correlates with the probability of acceptance of the same host in the larvae. We also found a negative relationship between stages within individuals as there was a higher acceptance of lower ranked hosts in females who had abandoned said host as a larva. Notably, however, neonate larvae of the comma butterfly did not unconditionally accept to feed from the least favorable host species even when it was the only food source. Our results suggest the possibility that the disadvantages associated with a generalist oviposition strategy can be decreased by larval participation in host plant choice.
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| 33. |
- Gamberale-Stille, Gabriella, et al.
(författare)
-
Selective attention by priming in host search behavior of 2 generalist butterflies
- 2019
-
Ingår i: Behavioral Ecology. - : Oxford University Press (OUP). - 1045-2249 .- 1465-7279. ; 30:1, s. 142-149
-
Tidskriftsartikel (refereegranskat)abstract
- We show that females of 2 generalist butterflies improve their search efficacy after previous encounters of the same host in a way similar to search-image formation, especially if the butterfly-host relationship is historically old. Thus, by targeting a single host at a time, host search efficacy may be improved and constitute a selection pressure for specialization. This result can help explain the evolutionary trend toward host specialization in phytophagous insects that is not well understood. Abstract In phytophagous insects such as butterflies, there is an evolutionary trend toward specialization in host plant use. One contributing mechanism for this pattern may be found in female host search behavior. Since search attention is limited, generalist females searching for hosts for oviposition may potentially increase their search efficacy by aiming their attention on a single host species at a time, a behavior consistent with search image formation. Using laboratory reared and mated females of 2 species of generalist butterflies, the comma, Polygonia c-album, and the painted lady, Vanessa cardui (Lepidoptera: Nymphalidae), we investigated the probability of finding a specific target host (among nonhost distractors) immediately after being primed with an oviposition experience of the same host as compared with different host in indoor cages. We used species-specific host plants that varied with respect to growth form, historical age of the butterfly-host association, and relative preference ranking. We found improved search efficacy after previous encounters of the same host for some but not all host species. Positive priming effects were found only in hosts with which the butterfly has a historically old relationship and these hosts are sometimes also highly preferred. Our findings provides additional support for the importance of behavioral factors in shaping the host range of phytophagous insects, and show that butterflies can attune their search behavior to compensate for negative effects of divided attention between multiple hosts.
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| 34. |
- Gotthard, Karl, et al.
(författare)
-
Individual state controls temperature dependence in a butterfly (Lasiommata maera)
- 2000
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 267:1443, s. 589-93
-
Tidskriftsartikel (refereegranskat)abstract
- In ectotherms there is typically a strong and positive correlation between growth rate and ambient temperature when food is not limiting. However, the exact relationship between growth rate and temperature varies among populations in many species. As a consequence, it has been suggested that selection for a rapid increase in growth rate with temperature should be stronger in populations experiencing a high degree of time-stress, compared with populations experiencing little time-stress. In the present study we take this adaptive hypothesis further and investigate if variation in time-stress among individuals of a single population may affect the relationship between growth rate and ambient temperature. Time-stress was manipulated by rearing larvae of the butterfly Lasiommata maera in different day-length regimes. The results show that individuals experiencing a higher degree of time-stress increase their growth rates more in higher temperatures compared with individuals under less time-stress. Hence, the adaptive hypothesis was supported and the relationship between growth rate and temperature was highly state dependent. These findings may be of general importance for understanding the evolution of life histories in seasonal environments.
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| 35. |
- Hill, Jason, et al.
(författare)
-
Unprecedented reorganization of holocentric chromosomes provides insights into the enigma of lepidopteran chromosome evolution
- 2019
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 5:6
-
Tidskriftsartikel (refereegranskat)abstract
- Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.
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| 36. |
- Houshuai, Wang, et al.
(författare)
-
Molecular phylogeny of Lymantriinae (Lepidoptera, Noctuoidea, Erebidae) inferred from eight gene regions
- 2015
-
Ingår i: Cladistics. - : Wiley. - 0748-3007 .- 1096-0031. ; 31:6, s. 579-592
-
Tidskriftsartikel (refereegranskat)abstract
- To understand the evolutionary history of Lymantriinae and test the present higher-level classification, we performed the first broad-scale molecular phylogenetic analysis of the subfamily, based on 154 exemplars representing all recognized tribes and drawn from all major biogeographical regions. We used two mitochondrial genes (cytochrome c oxidase subunit I and 16S ribosomal RNA) and six nuclear genes (elongation factor-1α, carbamoylphosphate synthase domain protein, ribosomal protein S5, cytosolic malate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase and wingless). Data matrices (in total 5424 bp) were analysed by parsimony and model-based evolutionary methods (maximum likelihood and Bayesian inference). Based on the results of the analyses, we present a new phylogenetic classification for Lymantriinae composed of seven well-supported tribes, two of which are proposed here as new: Arctornithini, Leucomini, Lymantriini, Orgyiini, Nygmiini, Daplasini trib. nov. and Locharnini trib. nov. We discuss the internal structure of each of these tribes and address some of the more complex problems with the genus-level classification, particularly within Orgyiini and Nygmiini.
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| 37. |
- Janz, Niklas, et al.
(författare)
-
Diversity begets diversity : host expansions and the diversification of plant-feeding insects
- 2006
-
Ingår i: BMC Evolutionary Biology. - 1471-2148. ; 6:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Plant-feeding insects make up a large part of earth's total biodiversity. While it has been shown that herbivory has repeatedly led to increased diversification rates in insects, there has been no compelling explanation for how plant-feeding has promoted speciation rates. There is a growing awareness that ecological factors can lead to rapid diversification and, as one of the most prominent features of most insect-plant interactions, specialization onto a diverse resource has often been assumed to be the main process behind this diversification. However, specialization is mainly a pruning process, and is not able to actually generate diversity by itself. Here we investigate the role of host colonizations in generating insect diversity, by testing if insect speciation rate is correlated with resource diversity.Results: By applying a variant of independent contrast analysis, specially tailored for use on questions of species richness (MacroCAIC), we show that species richness is strongly correlated with diversity of host use in the butterfly family Nymphalidae. Furthermore, by comparing the results from reciprocal sister group selection, where sister groups were selected either on the basis of diversity of host use or species richness, we find that it is likely that diversity of host use is driving species richness, rather than vice versa.Conclusion: We conclude that resource diversity is correlated with species richness in the Nymphalidae and suggest a scenario based on recurring oscillations between host expansions – the incorporation of new plants into the repertoire – and specialization, as an important driving force behind the diversification of plant-feeding insects.
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| 38. |
- Janz, Niklas, et al.
(författare)
-
No effect of larval experience on adult host preferences in Polygonia c-album (Lepidoptera: Nymphalidae): on the persistence of Hopkins' host selection principle
- 2009
-
Ingår i: Ecological Entomology. - Oxford : Blackwell. - 0307-6946 .- 1365-2311. ; 34:1, s. 50-57
-
Tidskriftsartikel (refereegranskat)abstract
- 1. The possible effect of juvenile imprinting or 'chemical legacy' on the subsequent oviposition - often called the 'Hopkins' host selection principle' - has been a controversial but recurrent theme in the literature on host-plant preference. While it appears possible in principle, experimental support for the hypothesis is equivocal. The present study points out that it is also important to consider its theoretical implications, and asks under what circumstances, if any, it should be favoured by natural selection. 2. Following this reasoning, it is predicted that host preference in the polyphagous butterfly Polygonia c-album L. (Lepidoptera, Nymphalidae) should not be influenced by larval environment. This was tested by rearing larvae on three natural host plants: the high-ranked Urtica dioica and the medium-ranked Salix cinerea and Ribes uva-crispa, and exposing the naive females to oviposition choices involving the same set of plants. 3. It was found that larval host plant had no effect on oviposition decisions of the adult female. Hence, the Hopkins' host selection principle does not seem to be applicable in this species. 4. Based on recent insights on how accuracy of environmental versus genetic information should affect the control of developmental switches, the conditions that could favour the use of juvenile cues in oviposition decisions are discussed. Although the Hopkins' host selection hypothesis cannot be completely ruled out, we argue that the circumstances required for it to be adaptive are so specific that it should not be invoked as a general hypothesis for host selection in plant-feeding insects.
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| 39. |
- Janz, Niklas, et al.
(författare)
-
On oscillations and flutterings-A reply to Hamm and Fordyce
- 2016
-
Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 70:5, s. 1150-1155
-
Tidskriftsartikel (refereegranskat)abstract
- The diversification of plant-feeding insects is seen as a spectacular example of evolutionary radiation. Hence, developing hypotheses to explain this diversification, and methods to test them, is an important undertaking. Some years ago, we presented the oscillation hypothesis as a general process that could drive diversification of this and similar interactions, through repeated expansions and contractions of host ranges. Hamm and Fordyce recently presented a study with the outspoken intention of testing this hypothesis where they concluded that the oscillation hypothesis was not supported. We point out several problems with their study, owing both to a misrepresentation of our hypothesis and to the methods. We provide a clarifying description of the oscillation hypothesis, and detail some predictions that follow from it. A reanalysis of the data demonstrated a troubling sensitivity of the "SSE" class of models to small changes in model specification, and we caution against using them for tests of trait-based diversification. Future tests of the hypothesis also need to better acknowledge the processes behind the host range oscillations. We suspect that doing so will resolve some of the apparent conflicts between our hypothesis and the view presented by Hamm and Fordyce.
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| 40. |
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| 41. |
- Keehnen, Naomi, et al.
(författare)
-
Geographic variation in hemocyte diversity and phagocytic propensity shows a diffuse genomic signature in the green veined white butterfly
- 2024
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Insects rely on their innate immune system to successfully mediate complex interactions with their internal microbiota, as well as the microbes present in the environment. Given the variation in microbes across habitats, the challenges to respond to them is likely to result in local adaptation in the immune system. Here we focus upon phagocytosis, a mechanism by which pathogens and foreign particles are engulfed in order to be contained, killed and processed for antigen presentation. We investigated the phenotypic and genetic variation related to phagocytosis, in two allopatric populations of the butterfly Pieris napi. We found that the populations differ in their hemocyte composition, and overall phagocytic capability, driven by the increased phagocytic propensity of each cell type. However, no evidence for divergence in phagocytosis-related genes was observed, though an enrichment of genes involved in glutamine metabolism was found, which have recently been linked to immune cell differentiation in mammals.
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| 42. |
- Keehnen, Naomi L.P., et al.
(författare)
-
A Population Genomic Investigation of Immune Cell Diversity and Phagocytic Capacity in a Butterfly
- 2021
-
Ingår i: Genes. - : MDPI AG. - 2073-4425 .- 2073-4425. ; 12:2
-
Tidskriftsartikel (refereegranskat)abstract
- Insects rely on their innate immune system to successfully mediate complex interactions with their internal microbiota, as well as the microbes present in the environment. Given the variation in microbes across habitats, the challenges to respond to them are likely to result in local adaptations in the immune system. Here we focus upon phagocytosis, a mechanism by which pathogens and foreign particles are engulfed in order to be contained, killed, and processed. We investigated the phenotypic and genetic variation related to phagocytosis in two allopatric populations of the butterfly Pieris napi. Populations were found to differ in their hemocyte composition and overall phagocytic capability, driven by the increased phagocytic propensity of each cell type. Yet, genes annotated to phagocytosis showed no large genomic signal of divergence. However, a gene set enrichment analysis on significantly divergent genes identified loci involved in glutamine metabolism, which recently have been linked to immune cell differentiation in mammals. Together these results suggest that heritable variation in phagocytic capacity arises via a quantitative trait architecture with variation in genes affecting the activation and/or differentiation of phagocytic cells, suggesting them as potential candidate genes underlying these phenotypic differences.
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| 43. |
- Keehnen, Naomi L. P., et al.
(författare)
-
Microevolutionary selection dynamics acting on immune genes of the green-veined white butterfly, Pieris napi
- 2018
-
Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 27:13, s. 2807-2822
-
Tidskriftsartikel (refereegranskat)abstract
- Insects rely on their innate immune system to successfully mediate complex interactions with their microbiota, as well as the microbes present in the environment. Previous work has shown that components of the canonical immune gene repertoire evolve rapidly and have evolutionary characteristics originating from interactions with fast-evolving microorganisms. Although these interactions are likely to vary among populations, there is a poor understanding of the microevolutionary dynamics of immune genes, especially in non-Dipteran insects. Here, we use the full set of canonical insect immune genes to investigate microevolutionary dynamics acting on these genes between and among populations by comparing three allopatric populations of the green-veined white butterfly, Pieris napi (Linne; Lepidoptera, Pieridae). Immune genes showed increased genetic diversity compared to genes from the rest of the genome and various functional categories exhibited different types of signatures of selection, at different evolutionary scales, presenting a complex pattern of selection dynamics. Signatures of balancing selection were identified in 10 genes, and 17 genes appear to be under positive selection. Genes involved with the cellular arm of the immune response as well as the Toll pathway appear to be enriched among our outlier loci, regardless of functional category. This suggests that the targets of selection might focus upon an entire pathway, rather than functional subsets across pathways. Our microevolutionary results are similar to previously observed macroevolutionary patterns from diverse taxa, suggesting that either the immune system is robust to dramatic differences in life history and microbial communities, or that diverse microbes exert similar selection pressures.
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| 44. |
- Keehnen, Naomi L. P., et al.
(författare)
-
Physiological Tradeoffs of Immune Response Differs by Infection Type in Pieris napi
- 2021
-
Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the tradeoffs that result from successful infection responses is central to understanding how life histories evolve. Gaining such insights, however, can be challenging, as they may be pathogen specific and confounded with experimental design. Here, we investigated whether infection from gram positive or negative bacteria results in different physiological tradeoffs, and whether these infections impact life history later in life (post-diapause development), in the butterfly Pieris napi. During the first 24 h after infection (3, 6, 12, and 24 h), after removing effects due to injection, larvae infected with Micrococcus luteus showed a strong suppression of all non-immunity related processes while several types of immune responses were upregulated. In contrast, this tradeoff between homeostasis and immune response was much less pronounced in Escherichia coli infections. These differences were also visible long after infection, via weight loss and slower development, as well as an increased mortality at higher infection levels during later stages of development. Individuals infected with M. luteus, compared to E. coli, had a higher mortality rate, and a lower pupal weight, developmental rate and adult weight. Further, males exhibited a more negative impact of infection than females. Thus, immune responses come at a cost even when the initial infection has been overcome, and these costs are likely to affect later life history parameters with fitness consequences.
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| 45. |
- Keehnen, Naomi L. P., et al.
(författare)
-
The consequences of surviving infection across the metamorphic boundary : tradeoff insights from RNAseq and life history measures
- 2024
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The broad diversity of insect life has been shaped, in part, by pathogen pressure, yet the influence of injury and infection during critical periods of development is understudied. During development, insects undergo metamorphosis, wherein the organism experiences a dramatic shift in their overall morphology, and physiology. In temperate zones, metamorphosis is often directly followed by a developmental arrest called diapause, for which the insect needs to acquire enough energy reserves before the onset of winter. We investigated the long-term effects of injury and infection using two bacteria in the butterfly Pieris napi, revealing that the negative consequences of bacterial infection carry across the metamorphic boundary. Initial direct effects of infection were weight loss and slower development, as well as an increased mortality at higher infection levels. The detrimental effects were stronger in the gram-positive Micrococcus luteus compared to gram-negative Escherichia coli. Transcriptome-wide differences between the two bacteria were already observed in the gene expression profile of the first 24 hours after infection. Larvae infected with M. luteus showed a strong suppression of all non-immunity related processes, with several types of immune responses being activated. The impact of these transcriptomic changes, a tradeoff between homeostasis and immune response, were visible in the life history data, wherein individuals infected with M. luteus had the highest mortality rate, along with the lowest pupal weight, developmental rate and adult weight of all the treatments. Overall, we find that the cost of infection and wounding in the final larval instar carries over the metamorphic boundary, and is expected to negatively affect their lifetime fitness.
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| 46. |
- Kodandaramaiah, Ullasa, et al.
(författare)
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Investigating concordance among genetic data, subspecies circumscriptions and hostplant use in the nymphalid butterfly polygonia faunus
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:7, s. e41058-
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Tidskriftsartikel (refereegranskat)abstract
- Subspecies are commonly used taxonomic units to formally describe intraspecific geographic variation in morphological traits. However, the concept of subspecies is not clearly defined, and there is little agreement about what they represent in terms of evolutionary units, and whether they can be used as reliably useful units in conservation, evolutionary theory and taxonomy. We here investigate whether the morphologically well-characterized subspecies in the North American butterfly Polygonia faunus are supported by genetic data from mitochondrial sequences and eight microsatellite loci. We also investigate the phylogeographic structure of P. faunus and test whether similarities in host-plant use among populations are related to genetic similarity. Neither the nuclear nor the mitochondrial data corroborated subspecies groupings. We found three well defined genetic clusters corresponding to California, Arizona and (New Mexico+Colorado). There was little structuring among the remaining populations, probably due to gene flow across populations. We found no support for the hypothesis that similarities in host use are related to genetic proximity. The results indicate that the species underwent a recent rapid expansion, probably from two glacial refugia in western North America. The mitochondrial haplotype network indicates at least two independent expansion phases into eastern North America. Our results clearly demonstrate that subspecies in P. faunus do not conform to the structuring of genetic variation. More studies on insects and other invertebrates are needed to better understand the scope of this phenomenon. The results of this study will be crucial in designing further experiments to understand the evolution of hostplant utilization in this species.
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| 47. |
- Kodandaramaiah, Ullasa, et al.
(författare)
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Phylogenetics of Coenonymphina (Nymphalidae Satyrinae) and the problem of rooting rapid radiations
- 2010
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 54:2, s. 386-394
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Tidskriftsartikel (refereegranskat)abstract
- We report a rapid radiation of a group of butterflies within the family Nymphalidae and examine some aspects of popular analytical methods in dealing with rapid radiations. We attempted to infer the phylogeny of butterflies belonging to the subtribe Coenonymphina sensu lato using five genes (4398bp) with Maximum Parsimony, Maximum Likelihood and Bayesian analyses. Initial analyses suggested that the group has undergone rapid speciation within Australasia. We further analyzed the dataset with different outgroup combinations the choice of which had a profound effect on relationships within the ingroup. Modelling methods recovered Coenonymphina as a monophyletic group to the exclusion of Zipaetis and Orsotriaena, irrespective of outgroup combination. Maximum Parsimony occasionally returned a polyphyletic Coenonymphina, with Argyronympha grouping with outgroups, but this was strongly dependent on the outgroups used. We analyzed the ingroup without any outgroups and found that the relationships inferred among taxa were different from those inferred when either of the outgroup combinations was used, and this was true for all methods. We also tested whether a hard polytomy is a better hypothesis to explain our dataset, but could not find conclusive evidence. We therefore conclude that the major lineages within Coenonymphina form a near-hard polytomy with regard to each other. The study highlights the importance of testing different outgroups rather than using results from a single outgroup combination of a few taxa, particularly in difficult cases where basal nodes appear to receive low support. We provide a revised classification of Coenonymphina; Zipaetis and Orsotriaena are transferred to the tribe Eritina.
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| 48. |
- Kodandaramaiah, Ullasa, et al.
(författare)
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Population structure in relation to host-plant ecology and Wolbachia infestation in the comma butterfly
- 2011
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 24:10, s. 2173-2185
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Tidskriftsartikel (refereegranskat)abstract
- Experimental work on Polygonia c-album, a temperate polyphagous butterfly species, has shown that Swedish, Belgian, Norwegian and Estonian females are generalists with respect to host-plant preference, whereas females from UK and Spain are specialized on Urticaceae. Female preference is known to have a strong genetic component. We test whether the specialist and generalist populations form respective genetic clusters using data from mitochondrial sequences and 10 microsatellite loci. Results do not support this hypothesis, suggesting that the specialist and generalist traits have evolved more than once independently. Mitochondrial DNA variation suggests a rapid expansion scenario, with a single widespread haplotype occurring in high frequency, whereas microsatellite data indicate strong differentiation of the Moroccan population. Based on a comparison of polymorphism in the mitochondrial data and sequences from a nuclear gene, we show that the diversity in the former is significantly less than that expected under neutral evolution. Furthermore, we found that almost all butterfly samples were infected with a single strain of Wolbachia, a maternally inherited bacterium. We reason that indirect selection on the mitochondrial genome mediated by a recent sweep of Wolbachia infection has depleted variability in the mitochondrial sequences. We also surmise that P. c-album could have expanded out of a single glacial refugium and colonized Morocco recently.
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| 49. |
- Kubrak, Olga I., et al.
(författare)
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Adaptation to fluctuating environments in a selection experiment with Drosophila melanogaster
- 2017
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:11, s. 3796-3807
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Tidskriftsartikel (refereegranskat)abstract
- A fundamental question in life-history evolution is how organisms cope with fluctuating environments, including variation between stressful and benign conditions. For short-lived organisms, environments commonly vary between generations. Using a novel experimental design, we exposed wild-derived Drosophila melanogaster to three different selection regimes: one where generations alternated between starvation and benign conditions, and starvation was always preceded by early exposure to cold; another where starvation and benign conditions alternated in the same way, but cold shock sometimes preceded starvation and sometimes benign conditions; and a third where conditions were always benign. Using six replicate populations per selection regime, we found that selected flies increased their starvation resistance, most strongly for the regime where cold and starvation were reliably combined, and this occurred without decreased fecundity or extended developmental time. The selected flies became stress resistant, displayed a pronounced increase in early life food intake and resource storage. In contrast to previous experiments selecting for increased starvation resistance in D. melanogaster, we did not find increased storage of lipids as the main response, but instead that, in particular for females, storage of carbohydrates was more pronounced. We argue that faster mobilization of carbohydrates is advantageous in fluctuating environments and conclude that the phenotype that evolved in our experiment corresponds to a compromise between the requirements of stressful and benign environments.
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| 50. |
- Kubrak, Olga I., et al.
(författare)
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Characterization of Reproductive Dormancy in Male Drosophila melanogaster
- 2016
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Ingår i: Frontiers in Physiology. - : Frontiers Media SA. - 1664-042X. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Insects are known to respond to seasonal and adverse environmental changes by entering dormancy, also known as diapause. In some insect species, including Drosophila melanogaster, dormancy occurs in the adult organism and postpones reproduction. This adult dormancy has been studied in female flies where it is characterized by arrested development of ovaries, altered nutrient stores, lowered metabolism, increased stress and immune resistance and drastically extended lifespan. Male dormancy, however, has not been investigated in D. melanogaster, and its physiology is poorly known in most insects. Here we show that unmated 3-6 h old male flies placed at low temperature (11 degrees C) and short photoperiod (10 Light:14 Dark) enter a state of dormancy with arrested spermatogenesis and development of testes and male accessory glands. Over 3 weeks of diapause we see a dynamic increase in stored carbohydrates and an initial increase and then a decrease in lipids. We also note an up-regulated expression of genes involved in metabolism, stress responses and innate immunity. Interestingly, we found that male flies that entered reproductive dormancy do not attempt to mate females kept under non-diapause conditions (25 degrees C, 1 2L:1 2D), and conversely non-diapausing males do not mate females in dormancy. In summary, our study shows that male D. melanogaster can enter reproductive dormancy. However, our data suggest that dormant male flies deplete stored nutrients faster than females, studied earlier, and that males take longer to recover reproductive capacity after reintroduction to non-diapause conditions.
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