| 1. |
- Blow, Rachel, et al.
(författare)
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A molecular phylogeny of forktail damselflies (genus Ischnura) reveals a dynamic macroevolutionary history of female colour polymorphisms
- 2021
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 160
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Tidskriftsartikel (refereegranskat)abstract
- Colour polymorphisms are popular study systems among biologists interested in evolutionary dynamics, genomics, sexual selection and sexual conflict. In many damselfly groups, such as in the globally distributed genus Ischnura (forktails), sex-limited female colour polymorphisms occur in multiple species. Female-polymorphic species contain two or three female morphs, one of which phenotypically matches the male (androchrome or male mimic) and the other(s) which are phenotypically distinct from the male (heterochrome). These female colour polymorphisms are thought to be maintained by frequency-dependent sexual conflict, but their macroevolutionary histories are unknown, due to the lack of a robust molecular phylogeny. Here, we present the first time-calibrated phylogeny of Ischnura, using a multispecies coalescent approach (StarBEAST2) and incorporating both molecular and fossil data for 41 extant species (55% of the genus). We estimate the age of Ischnura to be between 13.8 and 23.4 millions of years, i.e. Miocene. We infer the ancestral state of this genus as female monomorphism with heterochrome females, with multiple gains and losses of female polymorphisms, evidence of trans-species female polymorphisms and a significant positive relationship between female polymorphism incidence and current geographic range size. Our study provides a robust phylogenetic framework for future research on the dynamic macroevolutionary history of this clade with its extraordinary diversity of sex-limited female polymorphisms.
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| 2. |
- Bukontaite, Rasa, et al.
(författare)
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Phylogeny, distribution and speciation in the endemic diving beetle genus Pachynectes on Madagascar
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Madagascar is well known for high levels of endemism in both the flora and fauna. More specifically most of Madagascars' endemic species have extremely restricted regional distributions, which is a characteristic of this large island’s biodiversity. Biologists are still struggling to understand the speciation processes that have produced this pattern of diversity. Several general hypotheses have been developed trying to explain the origin and microendemism of Malagasy species. Two main hypotheses focus on watersheds and climate gradients. Here, we use a phylogeny in combination with data on spatial distribution of the endemic diving beetle genus Pachynectes (Coleoptera: Dytiscidae: Bidessini) to critically evaluate the watershed versus the climatic gradient hypotheses of this river dwelling insect radiation. Based on field sampling from expeditions between 2006 and 2014, we first show that the species diversity in this genus is at least three times higher than previously believed. We reconstructed a molecular phylogeny based on five gene fragments and recovered three main clades: a western clade, an eastern clade and a "keeled" clade diagnosable based on an elytral keel. The western and keeled clades both occur mainly in the drier western parts of the country, while species in the eastern clade are typical of rivers in the eastern humid rainforest. Notably, sister species were always allopatrically distributed along either latitudinal or longitudinal-altitudinal gradients. Based on species distribution modelling (SDM) and our phylogenetic data, we conclude that the microendemic patterns of Pachynectes species are unlikely to be explained by the watershed hypothesis. In contrast, the four main bioclimatic regions are more likely to have been causally involved in the past speciation processes and might explain the current distribution pattern in this insect genus.
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| 3. |
- Bybee, Seth, et al.
(författare)
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Odonata (dragonflies and damselflies) as a bridge between ecology and evolutionary genomics
- 2016
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Ingår i: Frontiers in Zoology. - : Springer Science and Business Media LLC. - 1742-9994. ; 13:1
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Forskningsöversikt (refereegranskat)abstract
- Odonata (dragonflies and damselflies) present an unparalleled insect model to integrate evolutionary genomics with ecology for the study of insect evolution. Key features of Odonata include their ancient phylogenetic position, extensive phenotypic and ecological diversity, several unique evolutionary innovations, ease of study in the wild and usefulness as bioindicators for freshwater ecosystems worldwide. In this review, we synthesize studies on the evolution, ecology and physiology of odonates, highlighting those areas where the integration of ecology with genomics would yield significant insights into the evolutionary processes that would not be gained easily by working on other animal groups. We argue that the unique features of this group combined with their complex life cycle, flight behaviour, diversity in ecological niches and their sensitivity to anthropogenic change make odonates a promising and fruitful taxon for genomics focused research. Future areas of research that deserve increased attention are also briefly outlined.
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| 4. |
- Chauhan, Pallavi, et al.
(författare)
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Genome assembly, sex-biased gene expression and dosage compensation in the damselfly Ischnura elegans
- 2021
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Ingår i: Genomics. - : Elsevier BV. - 0888-7543. ; 113:4, s. 1828-1837
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of sex chromosomes, and patterns of sex-biased gene expression and dosage compensation, are poorly known among early winged insects such as odonates. We assembled and annotated the genome of Ischnura elegans (blue-tailed damselfly), which, like other odonates, has a male-hemigametic sex-determining system (X0 males, XX females). By identifying X-linked genes in I. elegans and their orthologs in other insect genomes, we found homologies between the X chromosome in odonates and chromosomes of other orders, including the X chromosome in Coleoptera. Next, we showed balanced expression of X-linked genes between sexes in adult I. elegans, i.e. evidence of dosage compensation. Finally, among the genes in the sex-determining pathway only fruitless was found to be X-linked, while only doublesex showed sex-biased expression. This study reveals partly conserved sex chromosome synteny and independent evolution of dosage compensation among insect orders separated by several hundred million years of evolutionary history.
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| 5. |
- De Lisle, Stephen P, et al.
(författare)
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Climatic factors and species range position predict sexually antagonistic selection across taxa
- 2018
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Ingår i: Philosophical Transactions of the Royal Society B: Biological Sciences. - : The Royal Society. - 1471-2970 .- 0962-8436. ; 373:1757
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Tidskriftsartikel (refereegranskat)abstract
- Sex differences in selection are ubiquitous in sexually reproducing organisms. When the genetic basis of traits is shared between the sexes, such sexually antagonistic selection (SAS) creates a potential constraint on adaptive evolution. Theory and laboratory experiments suggest that environmental variation and the degree of local adaptation may all affect the frequency and intensity of SAS. Here, we capitalize on a large database of over 700 spatially or temporally replicated estimates of sex-specific phenotypic selection from wild populations, combined with data on microclimates and geographical range information. We performed a meta-analysis to test three predictions from SAS theory, that selection becomes more concordant between males and females: (1) in more stressful environments, (2) in more variable environments and (3) closer to the edge of the species' range. We find partial empirical support for all three predictions. Within-study analyses indicate SAS decreases in extreme environments, as indicated by a relationship with maximum temperature, minimum precipitation and evaporative potential (PET). Across studies, we found that the average level of SAS at high latitudes was lower, where environmental conditions are typically less stable. Finally, we found evidence for reduced SAS in populations that are far from the centre of their geographical range. However, and notably, we also found some evidence of reduced average strength of selection in these populations, which is in contrast to predictions from classical theoretical models on range limit evolution. Our results suggest that environmental lability and species range position predictably influence sex-specific selection and sexual antagonism in the wild.This article is part of the theme issue 'Linking local adaptation with the evolution of sex differences'.
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| 6. |
- De Lisle, Stephen P., et al.
(författare)
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On the standardization of fitness and traits in comparative studies of phenotypic selection
- 2017
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Ingår i: Evolution. - : Wiley. - 0014-3820. ; 71:10, s. 2313-2326
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Tidskriftsartikel (refereegranskat)abstract
- Comparisons of the strength and form of phenotypic selection among groups provide a powerful approach for testing adaptive hypotheses. A central and largely unaddressed issue is how fitness and phenotypes are standardized in such studies; standardization across or within groups can qualitatively change conclusions whenever mean fitness differs between groups. We briefly reviewed recent relevant literature, and found that selection studies vary widely in their scale of standardization, but few investigators motivated their rationale for chosen standardization approaches. Here, we propose that the scale at which fitness should be relativized should reflect whether selection is likely to be hard or soft; that is, the scale at which populations (or hypothetical populations in the case of a contrived experiment) are regulated. We argue that many comparative studies of selection are implicitly or explicitly focused on soft selection (i.e., frequency and density-dependent selection). In such studies, relative fitness should preferably be calculated using within-group means, although this approach is taken only occasionally. Related difficulties arise for the standardization of phenotypes. The appropriate scale at which standardization should take place depends on whether groups are considered to be fixed or random. We emphasize that the scale of standardization is a critical decision in empirical studies of selection that should always warrant explicit justification.
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| 7. |
- De Lisle, Stephen P., et al.
(författare)
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Phenotypic plasticity is aligned with phenological adaptation on both micro- and macroevolutionary timescales
- 2022
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Ingår i: Ecology Letters. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 25:4, s. 790-801
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Tidskriftsartikel (refereegranskat)abstract
- In seasonally variable environments, phenotypic plasticity in phenology may be critical for adaptation to fluctuating environmental conditions. Using an 18-generation longitudinal dataset from natural damselfly populations, we show that phenology has strongly advanced. Individual fitness data suggest this is likely an adaptive response towards a temperature-dependent optimum. A laboratory experiment revealed that developmental plasticity qualitatively matches the temperature dependence of selection, partially explaining observed advance in phenology. Expanding our analysis to the macroevolutionary level, we use a database of over 1-million occurrence records and spatiotemporally matched temperature data from 49 Swedish Odonate species to infer macroevolutionary dynamics of phenology. Phenological plasticity was more closely aligned with adaptation for species that have recently colonised northern latitudes, but with higher phenological mismatch at lower latitudes. Our results show that phenological plasticity plays a key role in microevolutionary dynamics within a single species, and such plasticity may have facilitated post-Pleistocene range expansion in this insect clade.
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| 8. |
- Deng, Junchen, et al.
(författare)
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Wolbachia-driven selective sweep in a range expanding insect species
- 2021
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Ingår i: BMC Ecology and Evolution. - : Springer Science and Business Media LLC. - 2730-7182. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Evolutionary processes can cause strong spatial genetic signatures, such as local loss of genetic diversity, or conflicting histories from mitochondrial versus nuclear markers. Investigating these genetic patterns is important, as they may reveal obscured processes and players. The maternally inherited bacterium Wolbachia is among the most widespread symbionts in insects. Wolbachia typically spreads within host species by conferring direct fitness benefits, and/or by manipulating its host reproduction to favour infected over uninfected females. Under sufficient selective advantage, the mitochondrial haplotype associated with the favoured maternally-inherited symbiotic strains will spread (i.e. hitchhike), resulting in low mitochondrial genetic variation across the host species range. Method: The common bluetail damselfly (Ischnura elegans: van der Linden, 1820) has recently emerged as a model organism for genetics and genomic signatures of range expansion during climate change. Although there is accumulating data on the consequences of such expansion on the genetics of I. elegans, no study has screened for Wolbachia in the damselfly genus Ischnura. Here, we present the biogeographic variation in Wolbachia prevalence and penetrance across Europe and Japan (including samples from 17 populations), and from close relatives in the Mediterranean area (i.e. I. genei: Rambur, 1842; and I. saharensis: Aguesse, 1958). Results: Our data reveal (a) multiple Wolbachia-strains, (b) potential transfer of the symbiont through hybridization, (c) higher infection rates at higher latitudes, and (d) reduced mitochondrial diversity in the north-west populations, indicative of hitchhiking associated with the selective sweep of the most common strain. We found low mitochondrial haplotype diversity in the Wolbachia-infected north-western European populations (Sweden, Scotland, the Netherlands, Belgium, France and Italy) of I. elegans, and, conversely, higher mitochondrial diversity in populations with low penetrance of Wolbachia (Ukraine, Greece, Montenegro and Cyprus). The timing of the selective sweep associated with infected lineages was estimated between 20,000 and 44,000 years before present, which is consistent with the end of the last glacial period about 20,000 years. Conclusions: Our findings provide an example of how endosymbiont infections can shape spatial variation in their host evolutionary genetics during postglacial expansion. These results also challenge population genetic studies that do not consider the prevalence of symbionts in many insects, which we show can impact geographic patterns of mitochondrial genetic diversity.
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| 9. |
- Dougherty, Liam R., et al.
(författare)
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A systematic map of studies testing the relationship between temperature and animal reproduction
- 2024
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Ingår i: Ecological Solutions and Evidence. - : John Wiley & Sons. - 2688-8319. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Exposure to extreme temperatures can negatively affect animal reproduction, by disrupting the ability of individuals to produce any offspring (fertility), or the number of offspring produced by fertile individuals (fecundity). This has important ecological consequences, because reproduction is the ultimate measure of population fitness: a reduction in reproductive output lowers the population growth rate and increases the extinction risk. Despite this importance, there have been no large-scale summaries of the evidence for effect of temperature on reproduction.We provide a systematic map of studies testing the relationship between temperature and animal reproduction. We systematically searched for published studies that statistically test for a direct link between temperature and animal reproduction, in terms of fertility, fecundity or indirect measures of reproductive potential (gamete and gonad traits).Overall, we collated a large and rich evidence base, with 1654 papers that met our inclusion criteria, encompassing 1191 species.The map revealed several important research gaps. Insects made up almost half of the dataset, but reptiles and amphibians were uncommon, as were non-arthropod invertebrates. Fecundity was the most common reproductive trait examined, and relatively few studies measured fertility. It was uncommon for experimental studies to test exposure of different life stages, exposure to short-term heat or cold shock, exposure to temperature fluctuations, or to independently assess male and female effects. Studies were most often published in journals focusing on entomology and pest control, ecology and evolution, aquaculture and fisheries science, and marine biology. Finally, while individuals were sampled from every continent, there was a strong sampling bias towards mid-latitudes in the Northern Hemisphere, such that the tropics and polar regions are less well sampled.This map reveals a rich literature of studies testing the relationship between temperature and animal reproduction, but also uncovers substantial missing treatment of taxa, traits, and thermal regimes. This database will provide a valuable resource for future quantitative meta-analyses, and direct future studies aiming to fill identified gaps.
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| 10. |
- Dudaniec, Rachael Y., et al.
(författare)
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Latitudinal clines in sexual selection, sexual size dimorphism and sex-specific genetic dispersal during a poleward range expansion
- 2022
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 91:6, s. 1104-1118
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Tidskriftsartikel (refereegranskat)abstract
- Range expansions can be shaped by sex differences in behaviours and other phenotypic traits affecting dispersal and reproduction. Here, we investigate sex differences in morphology, behaviour and genomic population differentiation along a climate-mediated range expansion in the common bluetail damselfly (Ischnura elegans) in northern Europe. We sampled 65 sites along a 583-km gradient spanning the I. elegans range in Sweden and quantified latitudinal gradients in site relative abundance, sex ratio and sex-specific shifts in body size and mating status (a measure of sexual selection). Using single nucleotide polymorphism (SNP) data for 426 individuals from 25 sites, we further investigated sex-specific landscape and climatic effects on neutral genetic connectivity and migration patterns. We found evidence for sex differences associated with the I. elegans range expansion, namely (a) increased male body size with latitude, but no latitudinal effect on female body size, resulting in reduced sexual dimorphism towards the range limit, (b) a steeper decline in male genetic similarity with increasing geographic distance than in females, (c) male-biased genetic migration propensity and (d) a latitudinal cline in migration distance (increasing migratory distances towards the range margin), which was stronger in males. Cooler mean annual temperatures towards the range limit were associated with increased resistance to gene flow in both sexes. Sex ratios became increasingly male biased towards the range limit, and there was evidence for a changed sexual selection regime shifting from favouring larger males in the south to favouring smaller males in the north. Our findings suggest sex-specific spatial phenotype sorting at the range limit, where larger males disperse more under higher landscape resistance associated with cooler climates. The combination of latitudinal gradients in sex-biased dispersal, increasing male body size and (reduced) sexual size dimorphism should have emergent consequences for sexual selection dynamics and the mating system at the expanding range front. Our study illustrates the importance of considering sex differences in the study of range expansions driven by ongoing climate change.
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