On the importance of inferring structure and on the recent evolutionary history of species

Lounès Chikhi (Université Paul Sabatier)

June 11, 2019, 12:45–13:45


Room MS 001


Genetic and genomic data are increasingly used to reconstruct the evolutionary history of species. The impressive power that DNA (from modern and ancient populations) provides to reconstruct ancient human movements, or identify the genetic connections between ancient human populations is difficult to deny. At the same time and given the apparent complexity of recent human evolutionary history it is also fair to ask whether the histories that are reconstructed are more than histories. To answer this kind of question it is crucial to improve our understanding of the properties of genetic and genomic data in complex structured populations and to understand the models on which the previous histories are built. A few years ago, with Olivier Mazet and colleagues from the IMT, INRA, IGC and the EDB laboratory, we developed a parameter which we called IICR (inverse instantaneous coalescence rate). The IICR can be seen a useful summary of genomic diversity. As such we are interested in its properties under different models of population structure. The IICR is interesting because under models of panmixia (with no structure) it can readily be interpreted as a function of population size change, and is estimated by the PSMC method that has been applied to many species. It has thus a natural and direct interpretation that the AFS (allele frequency spectrum) does not have. It is consequently complementary to the AFS, which contains other types of information and is used by many inferential methods. In this talk I will discuss the importance of population structure, present the results of our work on the IICR and discuss how this can be used to interpreted PSMC curves that are regularly published and interpreted under a total panmixia framework. I will finally link our work to recent human evolution including the recent interpretations of admixture with Neanderthals. IMT: Institut de Mathématiques de Toulouse - INRA: Institut National de Recherche Agronomique - EDB : Evolution et Diversité Biologique - IGC: Instituto Gulbenkian de Ciência


Lounès Chikhi (Université Paul Sabatier), On the importance of inferring structure and on the recent evolutionary history of species, IAST Lunch Seminar, Toulouse: IAST, June 11, 2019, 12:45–13:45, room MS 001.