Defense Date

3-2-2015

Graduation Date

Spring 2015

Availability

Immediate Access

Submission Type

dissertation

Degree Name

PhD

Department

Biological Sciences

Committee Chair

Michael Jensen-Seaman

Committee Member

Philip Auron

Committee Member

David Lampe

Committee Member

Philip Reno

Keywords

ACPP, Evolution, Gene Expression, Human Ancestor, KLK, Primates

Abstract

Hominoid primate species differ remarkably in their social grouping and mating systems, notably including differing degrees of post-copulatory sexual selection. As the mating system of extinct hominins remains unknown and difficult to predict, it may be useful to examine more proximate phenotypes correlated with behavior. For example, chimpanzees and bonobos have a large ejaculate that coagulates into a rigid copulatory plug, presumably in response to high levels of sperm competition, while gorillas have a small semi-viscous ejaculate associated with low sperm competition. To understand the molecular basis responsible for differences in semen biochemistry among hominoid species, I completed two research projects. First, by cloning the upstream putative promoters of the chimpanzee, bonobo, human, and gorilla prostatic acid phosphatase (ACPP) genes into luciferase reporter vectors followed by transient transfections into a human prostate cell line, I identified the underlying nucleotide changes that reduce expression of this protein in chimpanzee semen. Second, by mapping large deletions at the kallikrein-related peptidase (KLK) locus in the gorilla and gibbon genomes, I characterized the convergent gene loss and the formation of a novel chimeric gene in these monandrous species. For both the ACPP and KLK locus changes, I determined the polarity of the changes through outgroup comparison. At ACPP, the reduced expression in chimpanzee and bonobo is derived, and likely in response to the onset of intense sperm competition in the common ancestor of these two species. If this biochemical phenotype is indeed a proxy for mating behavior, my data provides some evidence (to be compared and contrasted with other molecular, behavioral, and paleontological data) that the last common ancestor of humans and chimpanzees was not chimp-like in its high degree of polyandry.

Format

PDF

Language

English

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