Lieu: Brunoy
Résumé: à venir.
Ithomiine butterflies (Nymphalidae: Ithomiini), also known as clearwing butterflies because of the partially transparent wings of most species, form a highly diverse tribe of ca. 390 species that occupy neotropical forests. All species have chemical defenses and are engaged in Müllerian mimicry: co-occurring species converge in wing colour pattern, thereby signaling their unpalatability to predators. We investigated temporal and spatial patterns of speciation and extinction, and we assessed the role of geological and ecological factors in the diversification of the group. We found that the geological dynamics of the Andean and upper Amazon regions had a considerable impact on the diversification of ithomiine butterflies during the Miocene, when the upper Amazon became flooded with water (Pebas mega-wetlands). The Pebas mega-wetland likely triggered extinctions in lowland lineages, while the concomitant rise of the Andes promoted speciation in montane lineages, which now form a highly diverse clade (80% of ithomiine extant species). The retreat of the Pebas during the late Miocene then further promoted speciation in those lineages, via the colonization of newly available lowland habitats. A closer examination of ecological factors with experimental and phylogenetic approaches highlights the role of ecological adaptation in speciation, such as wing colour patterns, hostplant and altitudinal niche. The combination of a highly dynamic geological history with intrinsic ecological traits have therefore largely contributed to the diversity of ithomiine butterflies. We are currently undertaking genomic studies to assess divergence between subspecies at the Andes/Amazonia interface, and to attempt to unravel the genomic bases of the variation in ecological traits.
