| 1. |
- Janz, Niklas, et al.
(författare)
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Diversity begets diversity : host expansions and the diversification of plant-feeding insects
- 2006
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Ingår i: BMC Evolutionary Biology. - 1471-2148. ; 6:1
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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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| 2. |
- Janz, Niklas, et al.
(författare)
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On oscillations and flutterings-A reply to Hamm and Fordyce
- 2016
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Ingår i: Evolution. - : Wiley. - 0014-3820 .- 1558-5646. ; 70:5, s. 1150-1155
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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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| 3. |
- Ma, Lijun, et al.
(författare)
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A phylogenomic tree inferred with an inexpensive PCR-generated probe kit resolves higher-level relationships among Neptis butterflies (Nymphalidae: Limenitidinae)
- 2020
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Ingår i: Systematic Entomology. - : Wiley. - 0307-6970 .- 1365-3113. ; 45:4, s. 924-934
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in obtaining reduced representation libraries for next-generation sequencing permit phylogenomic analysis of species-rich, recently diverged taxa. In this study, we performed sequence capture with homemade PCR-generated probes to study diversification among closely related species in a large insect genus to examine the utility of this method. We reconstructed the phylogeny of Neptis Fabricius, a large and poorly studied nymphalid butterfly genus distributed throughout the Old World. We inferred relationships among 108 Neptis samples using 89 loci totaling up to 84 519 bp per specimen. Our taxon sample focused on Palearctic, Oriental and Australasian species, but included 8 African species and outgroups from 5 related genera. Maximum likelihood and Bayesian analyses yielded identical trees with full support for almost all nodes. We confirmed that Neptis is not monophyletic because Lasippa heliodore (Fabricius) and Phaedyma amphion (Linnaeus) are nested within the genus, and we redefine species groups for Neptis found outside of Africa. The statistical support of our results demonstrates that the probe set we employed is useful for inferring phylogenetic relationships among Neptis species and likely has great value for intrageneric phylogenetic reconstruction of Lepidoptera. Based on our results, we revise the following two taxa: Neptis heliodore comb. rev. and Neptis amphion comb. rev.
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| 4. |
- Schäpers, Alexander, et al.
(författare)
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Clutch size and host use in butterflies - and how to measure diet breadth
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The utilization of host plants is a central aspect of herbivorous insect life-history and known to promote processes of diversification in this group. In species that aggregate their eggs, female selection of a suitable egg-laying site is especially important, since a large proportion of the realized fitness will depend on few oviposition events. A cluster of larvae also requires a large resource to complete development and thus resource size may further limit the range of suitable hosts. We investigated whether there is a relationship between clutch size and diet breadth for 206 nymphalid butterfly species, using phylogenetic comparative methods. Results were consistent across several taxonomic and phylogenetic diet breadth measures, suggesting that some taxonomic measures may be as good approximations as the more cumbersome estimates based on phylogenetic distance. Treating diet breadth and clutch size as continuous data indicated no relationship between the traits, while categorizing them into binary form showed that they evolve in a correlated fashion. The discordance between analyses indicated that clutch size may be constrained among extreme generalists, as polyphagous clutch layers were rare. We found clutch-laying to be a relatively conserved trait in the phylogeny and less flexible than variation in degree of host plant specialization. Host plant growth form did not influence the clutch size diet breath relationship, but was weakly correlated with both factors. We discuss the general role of conservative life-history traits, such as clutch size, for the evolutionary dynamics of more labile traits such as diet breadth among phytophagous insects.
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| 5. |
- Wang, Houshuai, et al.
(författare)
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Polyphagy and diversification in tussock moths : Support for the oscillation hypothesis from extreme generalists
- 2017
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:19, s. 7975-7986
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Tidskriftsartikel (refereegranskat)abstract
- Theory on plasticity driving speciation, as applied to insect-plant interactions (the oscillation hypothesis), predicts more species in clades with higher diversity of host use, all else being equal. Previous support comes mainly from specialized herbivores such as butterflies, and plasticity theory suggests that there may be an upper host range limit where host diversity no longer promotes diversification. The tussock moths (Erebidae: Lymantriinae) are known for extreme levels of polyphagy. We demonstrate that this system is also very different from butterflies in terms of phylogenetic signal for polyphagy and for use of specific host orders. Yet we found support for the generality of the oscillation hypothesis, in that clades with higher diversity of host use were found to contain more species. These clades also consistently contained the most polyphagous single species. Comparing host use in Lymantriinae with related taxa shows that the taxon indeed stands out in terms of the frequency of polyphagous species. Comparative evidence suggests that this is most probably due to its nonfeeding adults, with polyphagy being part of a resulting life history syndrome. Our results indicate that even high levels of plasticity can drive diversification, at least when the levels oscillate over time.
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| 6. |
- Agosta, Salvatore J, et al.
(författare)
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How specialists can be generalists : resolving the "parasite paradox" and implications for emerging infectious disease
- 2010
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Ingår i: Zoologia (Curitiba). - 1984-4670 .- 1984-4689. ; 27:2, s. 151-162
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Tidskriftsartikel (refereegranskat)abstract
- The parasite paradox arises from the dual observations that parasites (broadly construed, including phytophagous insects) are resource specialists with restricted host ranges, and yet shifts onto relatively unrelated hosts are common in the phylogenetic diversification of parasite lineages and directly observable in ecological time. We synthesize the emerging solution to this paradox: phenotypic flexibility and phylogenetic conservatism in traits related to resource use, grouped under the term ecological fitting, provide substantial opportunities for rapid host switching in changing environments, in the absence of the evolution of novel host-utilization capabilities. We discuss mechanisms behind ecological fitting, its implications for defining specialists and generalists, and briefly review empirical examples of host shifts in the context of ecological fitting. We conclude that host shifts via ecological fitting provide the fuel for the expansion phase of the recently proposed oscillation hypothesis of host range and speciation, and, more generally, the generation of novel combinations of interacting species within the geographic mosaic theory of coevolution. Finally, we conclude that taxon pulses, driven by climate change and large-scale ecological perturbation are drivers of biotic mixing and resultant ecological fitting, which leads to increased rates of rapid host switching, including the agents of Emerging Infectious Disease.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Audusseau, Hélène, et al.
(författare)
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Plant Fertilization Interacts with Life History : Variation in Stoichiometry and Performance in Nettle-Feeding Butterflies
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Variation in food stoichiometry affects individual performance and population dynamics, but it is also likely that species with different life histories should differ in their sensitivity to food stoichiometry. To address this question, we investigated the ability of the three nettle-feeding butterflies (Aglais urticae, Polygonia c-album, and Aglais io) to respond adaptively to induced variation in plant stoichiometry in terms of larval performance. We hypothesized that variation in larval performance between plant fertilization treatments should be functionally linked to species differences in host plant specificity. We found species-specific differences in larval performance between plant fertilization treatments that could not be explained by nutrient limitation. We showed a clear evidence of a positive correlation between food stoichiometry and development time to pupal stage and pupal mass in Aglais urticae. The other two species showed a more complex response. Our results partly supported our prediction that host plant specificity affects larval sensitivity to food stoichiometry. However, we suggest that most of the differences observed may instead be explained by differences in voltinism (number of generations per year). We believe that the potential of some species to respond adaptively to variation in plant nutrient content needs further attention in the face of increased eutrophication due to nutrient leakage from human activities.
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| 10. |
- Audusseau, Hélène, et al.
(författare)
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Rewiring of interactions in a changing environment : nettle-feeding butterflies and their parasitoids
- 2021
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 130:4, s. 624-636
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Tidskriftsartikel (refereegranskat)abstract
- Climate and land use change can alter the incidence and strength of biotic interactions, with important effects on the distribution, abundance and function of species. To assess the importance of these effects and their dynamics, studies quantifying how biotic interactions change in space and time are needed. We studied interactions between nettle-feeding butterflies and their shared natural enemies (parasitoids) locally and across 500 km latitudinal gradient in Sweden. We also examined the potential impact of the range-expansion of the butterfly Araschnia levana on resident butterflies via shared parasitoids, by studying how parasitism in resident butterflies covaries with the presence or absence of the newly-established species. We collected 6777 larvae of four nettle-feeding butterfly species (Aglais urticae, Aglais io, Ar. levana and Vanessa atalanta), over two years, at 19 sites distributed along the gradient. We documented the parasitoid complex for each butterfly species and measured their overlap, and analysed how parasitism rates were affected by butterfly species assemblage, variations in abundance, time, and the arrival of Ar. levana. Parasitoids caused high mortality, with substantial overlap in the complex of parasitoids associated with the four host butterflies. Levels of parasitism differed significantly among butterflies and were influenced by the local butterfly species assemblage. Our results also suggest that parasitism in resident butterflies is elevated at sites where Ar. levana has been established for a longer period. In our study system, variations in butterfly species assemblages were associated in a predictable way with substantial variations in rates of parasitism. This relationship is likely to affect the dynamics of the butterfly host species, and potentially cascade to the larger number of species with which they interact. These results highlight the importance of indirect interactions and their potential to reorganise ecological communities, especially in the context of shifts in species distributions in a warmer world.
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