Defense Date
7-5-2023
Graduation Date
Fall 12-15-2023
Availability
One-year Embargo
Submission Type
dissertation
Degree Name
PhD
Department
Biological Sciences
Committee Chair
Michael Jensen-Seaman
Committee Member
David Lampe
Committee Member
Wook Kim
Committee Member
Nathan Clark
Keywords
sexual selection, sperm competition, primates, TGM4, transglutaminase, sexual dimorphism
Abstract
Sexual selection is driven by the differential reproductive success of individuals, which is influenced by competition for mates and mate choice. In primates, this selective pressure has been attributed to the development of distinct anatomical, physiological, and behavioral characteristics. By employing comparative functional and genomic methodologies, this study aimed to assess the repercussions of primate sexual selection. To better understand the mechanisms driving sexually selected traits, an unbiased genome-wide analysis was used to associate rates of protein evolution with relative testes size and sexual size dimorphism. While previous research focused on the rapid evolution of male reproductive proteins in response to sexual selection, I detected strong conservation of testes-expressed proteins involved in male gamete generation and ciliary v form and function. Conversely, I found that the evolutionary rates of female reproductive proteins are accelerated in primates with large relative testes. I have also detected acceleration and conservation of proteins involved in the adaptive immune response, aligning with previous work suggesting an association between mating promiscuity and the evolution of pathogen defense genes. For functional analyses, I examined the prostate specific transglutaminase, TGM4, which is likely the driver of semen coagulation. The intensity of semen coagulation varies across primates, with some species forming a copulatory plug. Notably, TGM4 exhibits rapid evolution in chimpanzees, is nonfunctional in gorillas and gibbons, and is neutrally evolving or under relaxed constraint in humans. Using a mammalian expression system, recombinant human and chimpanzee TGM4 were expressed and tested in functional analyses. I found that chimpanzee TGM4 more readily crosslinks artificial substrates than human TGM4, which may be attributed to positive selection along the chimpanzee branch. Overall, the combination of genomic and functional analyses applied here demonstrate that sexual selection has impacted protein evolution leading to sequence variation and even functional differences between species.
Language
English
Recommended Citation
Ports, B. (2023). Comparative Functional and Genomic Analysis of Protein Targets Of Sexual Selection In Primates (Doctoral dissertation, Duquesne University). Retrieved from https://dsc.duq.edu/etd/2302