In humans, paleoclimatic changes may have triggered the demographic expansion out of Africa into novel environments, causing the appearance of numerous local adaptations in the newly founded populations.

Linking demography and adaptive responses to paleoclimatic history has rarely been undertaken in non-human great apes, but is pivotal to understanding the evolutionary history and the conservation of great ape populations.

We used whole-genome sequencing data from critically endangered orangutans from Sumatra (Pongo abelii n= 17) and Borneo (P. pygmaeus n = 20) to reconstruct the demographic history and investigate species-specific local adaptations. Approximate Bayesian Computation and Markovian coalescence analyses revealed strikingly disparate demographic histories of both orangutan species after their split ~700 ka.

In contrast to previous studies, we document a drastic collapse in effective population size (Ne) in the late Pleistocene, linked in Sumatra to the Toba volcanic supereruption ~73 ka. Both species have not recovered from this collapse, suggesting very limited scope of great ape populations to recover lost evolutionary potential. In line with well-documented persisting environmental differences between the islands, adaptive evolution took divergent paths. Markovian codon-modeling and haplotype-based statistics revealed that in the stable Sumatran environment, selection acted primarily on genes linked to brain development and learning, consistent with documented cognitive and behavioral differences between the species.

Biography

My broad interests are in the social evolution of both primates and cetaceans. Using DNA techniques, my work focuses on genetic relationships among cooperating individuals, quantifying reproductive success, and linking social correlates with population genetic and phylogeographic patterns. My group is also interested in reconstructing the demographic history of orang-utan populations, and delineating conservation units.

Another major interest of mine is the nature and transmission of culture in both primates and cetaceans. Studying the convergent evolution of culture in both marine and terrestrial habitats will help to understand what have led to the rise of human culture. More recently, my lab has started to employ population genomics approaches to identify the genetic signatures of adaptive evolution in orang-utans and dolphins. Using landscape genomics approaches, our work aims to disentangle adaptive evolution from non-adaptive processes such as genetic drift by taking into account demographic, stochastic and environmental processes.

This seminar is part of the Evolution, Ecology and Genetics Seminar Series