Biology subjects

Ledamoisel, J.

Publications and source records attributed to Ledamoisel, J..

7 recordsLinked to original sources

bioRxiv2026

Repeated evolution of convergent iridescence in closely-related species of Morpho butterflies living in sympatry

The evolution of visual traits in closely-related species living in sympatry is highly influenced by their ecological interactions: while sexual selection tends to promote the divergence of visual cues involved in mate choice, natural selection via predation may promote the convergence of dissuasive signals between prey species, especially in unpalatable or evasive prey. Here, we investigate the impact of sympatry on the evolution of the blue structural colouration in the wings of two closely-related Morpho butterfly species across several localities throughout Central and South America. Dorsal iridescence might affect mate choice and species recognition, which should promote its local divergence among species. However, the bright flashes and dynamic colour patterns produced by iridescence during flight might also increase survival by confusing predators and favouring escape. Such an effect might in turn lead to convergence in wing iridescence between evasive species occurring in sympatry, a phenomenon dubbed evasive mimicry. To test the effect of these putative antagonistic selective forces on visual cues evolution, we quantified the variation of the structural blue colour displayed at 13 different combinations of illumination/observation angles, on the wings of two closely-related Morpho species. We contrasted 10 sympatric and 11 allopatric locations and specifically compared the phenotypic distances between individuals from different species. Phenotypic distances between heterospecific pairs of individuals were significantly smaller in sympatry, consistent with the hypothesis of a local convergence of iridescence due to evasive mimicry. Interestingly, sexual dimorphism was found between males and females, suggesting that the trade-off between natural and sexual selection on the evolution of iridescence might differ between sexes. Our results suggest that local predation pressures may promote repeated evolutionary convergence of structural colouration between evasive prey species living in sympatry.

evolutionary biology↗

bioRxiv2025

Evolution of opsin genes in closely-related species of butterflies specialized in different microhabitats.

How do adaptive processes acting on the coevolution of opsin genes shape the evolution of colour vision in animals? At large phylogenetic scales, natural selection due to the contrasted light environments has been found to impact the evolution of photoreceptor genes. However, in closely-related species, species interactions due to sexual selection or competition may also influence opsin evolution. Here, we investigate the diversification of opsin sequences and their expression in closely-related blue Morpho butterfly species, living in different vertical strata within tropical forests, to shed light on the biotic and abiotic selective pressures shaping the coordinated evolution of opsin genes. We combined comparative genomics, transcriptomics, and immunochemistry to characterize the expression and the spatial distribution of the opsin proteins found in the eyes of Morpho helenor. We detected a double duplication of the LW opsin and found unique ommatidial types compared to other butterfly species. We then investigated the evolution of opsin genes among 21 Morpho species, found signatures of positive selection on two opsin genes (LW3Rh and BRh), and identified key co-evolving amino-acids within and among these two opsin genes. We showed that such opsin evolution was correlated with both light environment and wing coloration, highlighting the joint effect of several selective pressures in the coordinated evolution of proteins.

evolutionary biology↗

bioRxiv2025

Urbanisation and habitat fragmentation favour thermophilic and monogynous ant species

Environmental changes such as urbanisation and related habitat loss and fragmentation profoundly impact ecological communities by altering habitats, resources, and microclimates. Yet, the impacts of the resulting environmental conditions on metacommunity dynamics, ranging from species sorting to mass effects, remain a subject of debate. Ants, with diverse life histories and strong ecological effects, are ideal model species to study these pressures. We investigated the response of ant communities, including taxonomic and functional diversity, to urbanisation and habitat fragmentation in the Paris region, comparing wooded areas in 25 urban parks vs. 24 rural forests outside the city. We found a clear difference in species composition between urban and rural environments, with a higher prevalence of thermophilic species and a tendency for monogyny in the city. Forest communities were homogeneous across the size levels we studied, while park communities differed noticeably depending on park size, with larger parks harbouring more species. Our findings suggest that urbanisation selects specific ant traits and favours more thermophilic species, thereby increasing the mean thermal preference of urban communities. These selective effects influence which species can colonise and survive in different patches, shaping metacommunity structure and potentially affecting the resilience of ant communities under climate change.

ecology↗

bioRxiv2024

Sending mixed signals: convergent iridescence and divergent chemical signals in sympatric sister-species of Amazonian butterflies

The evolution of traits in closely related species living in sympatry strongly depends on both shared selective pressures and reproductive interference. In closely-related Morpho butterfly species living in the understory of the neo-tropical rainforest, the blue iridescent coloration of the wings is likely involved in predation evasion, as well as in mate recognition and courtship. We used spectrophotometry, behavioral experiments, visual modeling and chemical analyses to characterize the evolution of visual and chemical traits in two closely-related species, Morpho helenor and Morpho achilles. We specifically compared trait variation between samples from allopatric and sympatric populations of M. helenor to test the effect of ecological interactions with M. achilles on trait evolution. We quantified the differences in wing iridescence and tested for variations in the sexual preference for this trait. We found a strong similarity in iridescence between M. helenor and M. achilles in sympatry while the iridescence of M. helenor diverged in allopatry, suggesting that predation favors local resemblance. Although intraspecific behavioral experiments showed that iridescent signals could be used as visual cues during intraspecific mate choice, the strong resemblance of the iridescent signals between species may impair these species visual recognition. In contrast, the divergent chemical bouquets detected between species suggest that the visual similarity of sympatric Morpho species may have favored the divergence of alternative traits involved in species recognition, such as chemical cues.

evolutionary biology↗

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↗