An Ancestral Balanced Inversion Polymorphism Confers Global Adaptation

Abstract

Since the pioneering work of Dobzhansky in the 1940s, many chromosomal inversions have been identified but how they contribute to adaptation remains poorly understood. In Drosophila melanogaster, the widespread inversion polymorphism In(3R)P is involved in climate adaptation, exhibiting non-neutral latitudinal clines on multiple continents. Here, I summarize new results suggesting that this chromosomal rearrangement represents a long-term (equilibrium) balanced polymorphism of ancestral African origin and that it harbors alleles that are maintained by balancing selection on several continents. Our findings indicate that In(3R)P spread out of its ancestral subtropical/tropical range and then become latitudinally along similar but independent climatic gradients, always being frequent in subtropical/tropical areas but rare or absent in temperate climates.

Thomas Flatt

Thomas Flatt is Full Professor of Evolutionary Biology and Head of the Department of Biology at the University of Fribourg, Switzerland. Thomas' research interests are the genomic basis of adaptation, population genetics, and the evolution life histories and aging, mainly using Drosophila as a model system. He received his M.Sc. from the University of Basel in 1999 (supervisor: Prof. Stephen Stearns), for work done at the University of Sydney with Prof. Richard Shine, and his Ph.D. from Fribourg in 2004 (supervisor: Prof. Tadeusz Kawecki). Between 2004 and 2008, he was a postdoctoral researcher at Brown University with Prof. Marc Tatar and a visiting postdoc with Prof. Neal Silverman at UMass Medical School, funded by fellowships from the Swiss National Science Foundation (SNSF) and the Roche Research Foundation. Prior to taking up his position in Fribourg in 2017, he was a SNSF Professor in the Department of Ecology and Evolution at Lausanne (2012-17), a Fellow at the Wissenschaftskolleg Berlin (2012), a faculty member of the Vienna Graduate School of Population Genetics and a tenured group leader at the Institute of Population Genetics in Vienna (2009-12). Between 2018 and 2021 he held a DFG Mercator Fellowship and Visiting Professorship at the University of Münster. He has been serving on numerous editorial, advisory and reviewing panels and, with Josefa Gonzalez (Barcelona), co-leads an international consortium of researchers, the European Drosophila Population Genomics Consortium (DrosEU). He currently serves as an elected member of the National Research Council, the scientific body of the Swiss National Science Foundation (SNSF).