How Do the Largest and Smallest Baboon Species Compete for Reproductive Success in a Natural Hybrid Zone?
Date of Award
Doctor of Philosophy (PhD)
This dissertation examines hybridization between two of the most divergent baboons, the kinda baboon (Papio kindae) and the grayfooted chacma baboon (P. ursinus griseipes), which differ markedly in body size and in some social behavior. Preliminary research revealed hybridization between males of the smaller species (kinda) and females of the larger species (grayfoots), but not the reverse. Using behavioral, phenotypic, and genetic data collected from a single hybrid group in Kafue National Park from May 2012 to July 2013, I evaluated whether a similar asymmetry was borne out in this group and whether phenotypic markers of species assignation matched genotypic groupings based upon seven microsatellite markers. I assessed what factors were influential for male mating success in this group and explored whether mating and reproductive success could be explained by the priority-of-access model, whereby the dominant male realizes the most reproductive success. I investigated whether a modified form of this priority-of-access model, female preference for unusually "friendly" kinda males, and/or genetic or obstetric incompatibility might explain this proposed asymmetry. I found that while asymmetry is present in the overall hybrid zone, it was not found in this group. Phenotypic markers of species assignation did not match genotypic groupings. As in most other baboon species, dominance rank and mate guarding were the most influential factors in male reproductive success in this group, supporting the priority-of-access model. However, since Kinda-like males in this group groom more and have higher reproductive success, the asymmetry may be in part due to this “friendly” behavior. While mating occurred across all genotypes and phenotypes, the lack of hybrid offspring resulting from parents having opposite genetic backgrounds suggests possible genetic or obstetric incompatibility. Results from this study reveal that being a genetically Kinda-like male (regardless of phenotype) confers some sort of reproductive advantage. This study has helped clarify the importance of "friendly" male behavior in this unexpected asymmetry, provided insight into issues related to mate choice in hybrids, and revealed possible reproductive barriers to hybridization, as well as contributed to the corpus of knowledge of baboon diversity in general.
Chair and Committee
Crickette Sanz, Kari Allen, Alan Templeton, Clifford Jolly
McDonald, Monica, "How Do the Largest and Smallest Baboon Species Compete for Reproductive Success in a Natural Hybrid Zone?" (2016). Arts & Sciences Electronic Theses and Dissertations. 999.
Permanent URL: https://doi.org/10.7936/K76Q1VP1