Biology subjects

Ledamoisel, J.

Publications and source records attributed to Ledamoisel, J..

3 recordsLinked to original sources

bioRxiv2024

Increased evolutionary rate in the Z-chromosome of Morpho butterflies and implications for speciation.

The evolution of reproductive isolation between populations shapes divergence in genome structure and content: comparing the genomes of closely-related species can thus enlighten the speciation process. Comparisons of genomes of allopatric vs. sympatric species sharing similar vs. dissimilar ecological niches allows to specifically investigate the effect of reinforcement and ecological specialization on genome evolution. In the butterfly genus Morpho, several species can be found in sympatry presenting specialisation in different microhabitats and temporal niches. Here, we sequenced, assembled and annotated the genomes of 8 Morpho species and used previously published genomes of three other Morpho species to study genomic rearrangements and signatures of positive selection. We found extensive chromosomal rearrangements in the Z chromosome compared to the autosomes, particularly among closely related sympatric species occupying similar niches, pointing at the putative role of inversions in preventing gene flow at a postzygotic level. We also detected a higher proportion of genes under positive selection on the Z-chromosome compared to the autosomes, suggesting a potential role of the Z-chromosome in driving adaptive evolution in Morpho. Finally, because of the divergence in daily activities between species, we studied the evolution of eight genes involved in the circadian clock and detected a signature of positive selection on the gene Period, located in the Z chromosome. By studying the evolution of genome structure and coding sequences, our study indicates fast evolution of the Z-chromosome, partly driven by selection, throughout this genus, highlighting the putative implication of this sexual chromosome on pre and post-zygotic isolation.

evolutionary biology↗

bioRxiv2023

Habitat fragmentation selects for low dispersal in an ant species

Increased habitat fragmentation is one of the major global changes affecting biodiversity. It is characterised by a decrease in habitat availability and by an increase in the isolation of suitable habitat patches. The dispersal capacities of species may evolve in response to increased habitat fragmentation. Spatial heterogeneities and/or costs of dispersal, which are directly linked to habitat fragmentation, tend to select for lower dispersal abilities. We studied the effects of habitat fragmentation on dispersal using an ant species that exhibits a marked dispersal polymorphism. Myrmecina graminicola produces winged queens dispersing by flight over long distances, or apterous queens dispersing on foot over short distances. We sampled queens in 24 forests around Paris and 25 parks within Paris, representing varied levels of habitat fragmentation and habitat size. We identified the queen morphotypes in each environment and used it as a proxy of dispersal. Winged queens predominated in both environments. However, apterous queens were comparatively more common in parks than in forests, suggesting that high fragmentation counterselects dispersal in this species. We argue that this is because dispersing within urban environments is very costly and discuss the factors favouring each queen morph or resulting in their co-occurrence (maintenance of polymorphism).

evolutionary biology↗

bioRxiv2022

Evidence of attack deflection suggests adaptive evolution of wing tails in butterflies

Predation is a powerful selective force shaping many behavioural and morphological traits in prey species. The deflection of predator attacks from vital parts of the prey usually involves the coordinated evolution of prey body shape and colour. Here, we test the deflection effect of hindwing tails in the swallowtail butterfly Iphiclides podalirius. In this species, hindwings display long tails associated with a conspicuous colour pattern. By surveying the wings within a wild population of I. podalirius, we observed that wing damage was much more frequent on the tails. We then used a standardised behavioural assay employing dummy butterflies with real I. podalirius wings to study the location of attacks by great tits Parus major. Wing tails and conspicuous coloration of the hindwings were struck more often than the rest of the body by birds. Finally, we characterised the mechanical properties of fresh wings and found that the tail vein was more fragile than the others, suggesting facilitated escape ability of butterflies attacked at this location. Our results clearly support the deflective effect of hindwing tails and suggest that predation is an important selective driver of the evolution of wing tails and colour pattern in butterflies.

evolutionary biology↗