Graduation Year

2020

Date of Submission

12-2019

Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts

Department

W.M. Keck Science Department

Second Department

Biochemistry

Reader 1

Dr. Findley Finseth

Reader 2

Dr. Patrick Ferree

Abstract

Female meiotic drive is an unequal transmission of alleles that arises through the competition of paired chromosomes for inclusion in the egg, resulting in an increase in frequency of the driven alleles regardless of their effect on fitness of the individual. In Mimulus guttatus (monkeyflower) second filial generations, driven alleles display transmission advantages resulting in the virtual elimination of recessive homozygotes, while the equivalent lines lacking drive elements conform to traditional Mendelian segregation population ratios. Centromeres have been identified as mechanistic drive elements due to their role in chromosomal segregation during female meiosis, with Mimulus providing the best documented case of centromere-associated female meiotic drive. Here, abundance of centromeric sequence repeats, analogous to centromere size, is quantified and found to be elevated in driver populations, suggesting centromere size as a mechanism for female meiotic drive. A preliminary survey into centromere sequence variation also revealed divergence between driver and non-driver populations, implying centromeric sequence as a secondary mechanistic aspect to drive. The identification of drive related centromere characteristic variation supports a centromere-associated female meiotic drive model, and suggests specific mechanisms for further investigation to elucidate a formidable, but insufficiently understood evolutionary force.

Available for download on Thursday, December 09, 2021

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