Two stories on adaptive evolution in Ethiopian frogs
20 Apr 2022 - Stephane Boissinot, New York University Abu Dhabi, United Arab Emirates | 11h00
CASUAL SEMINAR IN BIODIVERSITY AND EVOLUTION
The Ethiopian highlands are a biodiversity hotspot, which harbors a large number of endemic species, particularly frogs. We discovered that grass frogs of the genus Ptychadena diversified rapidly in the Ethiopian highlands resulting in a monophyletic assemblage of 12 species, with specific altitudinal distributions. We use the Ethiopian Ptychadena radiation as a model system to investigate (1) the molecular basis of adaptation to high altitude and (2) the adaptive evolution of color polymorphisms. In the first part of the talk, I will show how combining comparative genomics and ecological niche modeling allows us to reconstruct the evolutionary history of the radiation and to determine the genomic changes underlying the diversification process. Biological pathways and functions predominantly associated with niche divergence and physiological adaptation to high elevation have been the target of strong positive selection. We also found that the number of genes under positive selection differs significantly among lineages and is related to the extent of niche divergence among species within lineage and to the harshness of the environment. In the second part of the talk, I will present an investigation on the evolution of the vertebral stripe, a cryptic color pattern, found in many species of frogs. The vertebral stripe has evolved hundreds of times and is favored in terrestrial habitats. We demonstrate that variation near the Agouti signaling protein gene (ASIP) is responsible for the different vertebral stripe phenotypes in the species Ptychadena robeensis. Surprisingly, and although the stripe phenotype is shared with closely related species, we found that the P. robeensis alleles are private to this species, thus indicating that the vertebral stripe phenotypes result from parallel evolution within the group. Our findings demonstrate that this cryptic color pattern evolves rapidly and recurrently in terrestrial anurans, and therefore constitute an ideal system to study repeated evolution.
Stéphane Boissinot is Professor Biology at New York University Abu Dhabi and Global Network Professor of Biology at the Faculty of Arts and Sciences at NYU New York. Prof. Boissinot is an evolutionary biologist who uses a combination of field-based, molecular and computational approaches to address fundamental biological questions. He has done research on a diversity of topics including the evolution of genome size and structure, the evolution of adaptation to extreme environments and the biogeography and population genetics of a number of vertebrate species. His research has been funded in the United States by the National Science Foundation and by the National Institutes of Health. He received his PhD from the University of Montpellier (France) on the evolution of the house mouse. He then held post-doctoral positions at the University of Texas where he studied the evolution of color vision in primates and at the National Institutes of Health where he worked on the evolution of mobile DNA elements in human. He was a member of the faculty in the Department of Biology at Queens College, the City University of New York, from 2003 to 2014. He joined NYU Abu Dhabi in spring 2015.
[Host: José Melo-Ferreira, Genomics of Evolutionary Change - EVOCHANGE]