HYBRIDBAB · GENETIC, BEHAVIOURAL, AND DEMOGRAPHIC CONSEQUENCES OF LONG-TERM HYBRIDIZATION IN SAVANNA BABOONS

Genetic, Behavioural, and Demographic Consequences of Long-term Hybridization in Savanna Babbons

The process and consequences of hybridisation are of interest to evolutionary biologists because of the importance of hybridisation in understanding reproductive isolation, speciation, and the influence of introgression on population genetic structure. In particular, hybridisation has been hypothesised to have played an important role in the evolution of the primate lineage, including potentially the evolution of our own species. Although many instances of naturally occurring hybridisation in primates have now been documented, we still lack a holistic understanding of how hybridisation impacts individual life histories in the short term and population and species evolution in the long term. The goal of the proposed project was to address this gap in our knowledge by gaining a detailed understanding of the genetic, behavioural and demographic consequences of hybridisation in the well-studied wild Amboseli baboon population in particular and across the boundary of the southern Kenyan baboon hybrid zone as a whole. Hybridisation between yellow baboons and anubis baboons has been well documented in the Amboseli basin of Kenya (population primarily composed of yellow baboons; Tung et al. 2008 Molecular Ecology), where more anubis-like individuals tend to experience fitness advantages in the form of earlier sexual maturation (Charpentier et al. 2008 Molecular Ecology). To know whether these anubis advantages are reflected in the genetic structure of populations surrounding the Amboseli area, we first genotyped about 200 individuals (at 12 microsatellite loci) in different populations surrounding the baboon hybrid zone. Isolation with migration analysis revealed asymmetric gene flow in this hybrid zone from anubis populations into yellow populations, in support of the anubis biased phenotypic advantages observed in Amboseli. Moreover, populations that are primarily yellow but that receive anubis gene flow exhibit higher levels of genetic diversity than yellow populations far from the introgression front. Our results support previous work that indicates a long history of hybridisation and introgression among East African baboons. Specifically, it suggests that anubis baboons are in the process of gradual range expansion into the range of yellow baboons, a pattern potentially explained by behavioural and life history advantages that correlate with anubis ancestry. Second, in order to confirm that anubis baboons present reproductive advantages, we studied patterns of mate choice; in particular, how admixture related genetic background affects mating behaviour. We identified novel effects of genetic background on mating patterns, including an advantage accruing to anubis-like males and assortative mating among both yellow-like and anubis-like pairs (see figure attached). These genetic effects acted alongside social dominance rank, inbreeding avoidance, and age to produce highly non-random mating patterns. Our results suggest that this population may be undergoing admixture-related evolutionary change, driven in part by non-random mating.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз