Biology subjects

Badiane, A.

Publications and source records attributed to Badiane, A..

4 recordsLinked to original sources

bioRxiv2026

Sexual conflict, directional sexual selection and phenotypic plasticity jointly drive the evolution of extreme phenotypic variation

How broad phenotypic variation is maintained in natural populations in the face of selection is a central question in evolutionary biology. We address this question in the water strider Microvelia longipes, where males exhibit striking variation in rear leg length used in male-male contests for dominance. Using reaction norm experiments on inbred lines, we demonstrate that phenotypic plasticity contributes to expanding phenotypic variation, but requires high genetic variation to generate the broad range of trait expression observed in natural populations. Experimental evolution favouring trait exaggeration revealed that directional sexual selection not only fails to erode variation of male rear leg length, but rather amplifies it beyond the natural distribution. Additionally, male-limited selection in favour of dominance generated substantial fecundity costs in females, underscoring the role of sexual conflict driven by females in constraining exaggerated secondary sexual traits in males. Our findings show that sexually antagonistic selection and directional sexual selection jointly generate high genetic variation, which phenotypic plasticity inflates into broad phenotypic distribution of male weapon size. This provides an empirical explanation for the high variability of male exaggerated weapons in nature.

evolutionary biology↗

bioRxiv2024

A single giant cell at the origin of an evolutionary innovation

Key innovations play a central role in the diversification of lineages, yet our understanding of the mechanisms underlying their emergence remains fragmented. The propelling fan is a key innovation associated with the diversification of Rhagovelia water striders into fast flowing streams. Here, we show that a single giant cell is responsible for the development of the fan throughout embryogenesis. RNA interference against the fan-specific gene family gsha/mogsha depleted the fan in the embryo but did not alter the giant cell, indicating that these genes are not required for specifying the identity of this cell. gsha/mogsha instead seem to activate the expression of cuticular genes during early development, suggesting a role of these genes in regulating the accumulation of fan structural proteins. We also show that Hox genes act to block the giant cell in the fore- and rear-legs, thus restricting its fate to the mid-legs - the pair of legs that generates movement on water. In addition, Hox expression is specifically excluded from the giant cell, thus allowing the expression of the fans developmental genetic program. This study reveals that a single cell can be sufficient to generate innovative traits that have been central for a lineage to acquire new ecological opportunities and burst into diversification. One-sentence summaryA single giant cell orchestrates the developmental genetic program of a key innovation

evolutionary biology↗

bioRxiv2022

Urbanisation impacts the diversity, coloration, and body size of wild bees in a Mediterranean city

Urbanisation is a growing phenomenon causing the decline of wild bees globally. Yet, bees manage to persist in the urban matrix thanks to islands of vegetation in public parks and private gardens. While we begin to comprehend the impact of urbanisation on bees diversity and abundance, our understanding of its impact on the functional diversity of wild bees is limited. Here, we use an integrative approach to investigate the response of wild bees to urbanisation at the community, species, and individual levels. To do so, we sampled wild bees in 24 public parks along an urbanisation gradient in the Mediterranean city of Marseille. We found that species richness and abundance decreased in more urbanised areas, but increased in larger city parks. Moreover, larger individuals within species, but not larger species, were found in larger city parks, suggesting that park size is crucial for the persistence of bees in cities. Interestingly, we show that brighter species were found in parks surrounded by a large amount of impervious surface, highlighting the importance of colour traits in the response to environmental changes. Finally, our results revealed that larger species, but not larger individuals, were also more colourful. In summary, our study not only confirmed that urbanisation negatively impacts community-level traits, but that it also affects species coloration and individuals body size, thus improving our understanding of the functional response of wild bees to urbanisation. We suggest that increasing park size may compensate for the negative effects of urbanisation on wild bees.

ecology↗

bioRxiv2021

Population genomics of wall lizards reflects the dynamic history of the Mediterranean Basin

The Mediterranean Basin has experienced extensive change in geology and climate over the past six million years. Yet, the relative importance of key geological events for the distribution and genetic structure of the Mediterranean fauna remains poorly understood. Here, we use population genomic and phylogenomic analyses to establish the evolutionary history and genetic structure of common wall lizards (Podarcis muralis). This species is particularly informative because, in contrast to other Mediterranean lizards, it is widespread across the Iberian, Italian, and Balkan peninsulas, and in extra-Mediterranean regions. We found strong support for six major lineages within P. muralis, which were largely discordant with the phylogenetic relationship of mitochondrial DNA. The most recent common ancestor of extant P. muralis was likely distributed in the Italian Peninsula, and experienced an "Out-of-Italy" expansion following the Messinian salinity crisis (~5 Mya), resulting in the differentiation into the extant lineages on the Iberian, Italian and Balkan peninsulas. Introgression analysis revealed that both inter- and intraspecific gene flow have been pervasive throughout the evolutionary history of P. muralis. For example, the Southern Italy lineage has a hybrid origin, formed through admixture between the Central Italy lineage and an ancient lineage that was the sister to all other P. muralis. More recent genetic differentiation is associated with the onset of the Quaternary glaciations, which influenced population dynamics and genetic diversity of contemporary lineages. These results demonstrate the pervasive role of Mediterranean geology and climate for the evolutionary history and population genetic structure of extant species.

evolutionary biology↗