Date of Graduation

8-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Anthropology (PhD)

Degree Level

Graduate

Department

Anthropology

Advisor/Mentor

Claire Terhune

Committee Member

Lucas Delezene

Second Committee Member

Katherine Willmore

Third Committee Member

Kathleen Paul

Keywords

Development, Fluctuating asymmetry, Geometric morphometrics, Primates, Skeletal morphology, Stress

Abstract

This dissertation explored the impact of environmental factors on the development and perpetuation of fluctuating asymmetry (FA) and sought to understand the role evolution may play in the FA exhibited in two primate populations: the free-ranging Cayo Santiago rhesus macaques (Macaca mulatta) and the Southwest National Primate Research Center olive baboons (Papio hamadryas anubis). Demographic, ontogenetic, secular, external, and genetic factors were examined. Specifically, this dissertation investigated FA over all ontogenetic stages, across decades, between sexes, in association with ecological catastrophes, and with tooth pathology to try and tease apart factors that may influence FA and developmental instability. This dissertation also estimated the heritability and evolvability of FA and used FA levels over decades to examine the role of evolutionary mechanisms on FA. In all, results show that the age at which a macaque experiences a hurricane and baboon antemortem tooth loss impact levels of FA. They also show that sex-related differences are present in the population of baboons but not the macaques. Additionally, FA does not seem to change ontogenetically in either the macaque or baboon population, and secular changes were only found in male baboons where FA decreased over time. Lastly, the heritability and evolvability of FA in the macaque and baboon populations were extremely low, though higher in baboons than macaques. This work suggests that FA levels may be sex-specific in species with extreme sexual dimorphism, and FA generally seems not to change over ontogeny in these populations. Secular changes in FA appear possible in primates, although the pattern remains ambiguous. This work also shows that ecological catastrophes such as hurricanes are likely critical determinants of FA later in life if experienced in utero. Lastly, FA seems to have some additive genetic variation that is subject to selection, though minimal. Overall, this work offers additional resolution in teasing apart factors contributing to FA and points to minimal genetic influence on FA levels.

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