Julianne Radford
- BSc Hons. (Western University, 2021)
Topic
Male fitness and the persistence of a selfish X chromosome in Drosophila testacea
Department of Biology
Date & location
- Thursday, May 9, 2024
- 10:00 A.M.
- Clearihue Building, Room B017
Examining Committee
Supervisory Committee
- Dr. Steve Perlman, Department of Biology, University of Victoria (Supervisor)
- Dr. Rana El-Sabaawi, Department of Biology, UVic (Member)
- Dr. Ryan Gawryluk, Department of Biology, UVic (Member)
External Examine
- Dr. Jennifer Perry, Biology Department, St. Francis Xavier University
Chair of Oral Examination
- Dr. Christopher Nelson, Department of Biochemistry and Microbiology, UVic
Abstract
Selfish X chromosomes bias their own transmission during reproduction by interfering with the transmission of Y-bearing sperm, a phenomenon best characterized in flies. Male flies carrying selfish X produce almost exclusively female offspring, which consequentially can reduce mean fitness in populations. Left unchecked, selfish X chromosomes may spread to fixation and result in extinction; therefore, one major question in the field is to understand how these chromosomes persist in nature. My research investigated one of two main hypotheses for selfish X persistence: the potential fitness consequences of harbouring the selfish element. The Palearctic woodland fly, Drosophila testacea, was recently found to carry an ancient selfish X chromosome, which serves as a great model for understanding how selfish X chromosomes persist over evolutionary time. My research used classical methods to investigate the contribution of male fitness effects in the persistence of this selfish X chromosome. I asked (1) if male age affects drive strength; (2) if male survival is affected by drive presence; (3) if female flies preferentially mate with wildtype or driver males; and (4) if female remating is affected by male genotype. I found that male age does not alter strength of drive, driver males do not suffer reduced survival compared to wildtype males, females do not exhibit mate discrimination against driver males, and female propensity to remate is not affected by male genotype. The present study indicates that in D. testacea, male fitness effects do not play a major role in drive persistence, and persistence over evolutionary time may be attributed other mechanisms such as genetic suppressors. Selfish X chromosomes are increasingly recognized as major players in organismal biology. Research on meiotic drive systems such as the selfish X chromosome in D. testacea will deepen our understanding of how gene drive persists over evolutionary time, and may provide insight on the prospect of synthetic gene drives.