Genes in a genome do not always play as an orchestra. Selfish meiotic drivers play by their own rules and can spread in populations–either killing other sperm during male meiosis or segregating preferentially into eggs during female meiosis to bias their transmission. Meiotic drivers generally arise in heterochromatic regions, which are also enriched for structural variations, e.g., inversions and translocations. Meiotic drivers frequently segregate with these structural variations, which may offer short-term advantages with long-term consequences. My dissertation shows how meiotic drivers shape genome evolution by enabling new structural variations to overcome their own deleterious effects and persist in populations.
I first assessed the impact of inversions and complex epistasis between genetic modifiers on known male driving chromosomes, Segregation Distorter (SD), in D. melanogaster. By surveying the driving effect of a marked SD chromosome in 90 inbred lines from a population from North Carolina (DGRP), we determined that multiple genetic modifiers affect the driving ability of SD chromosomes and suppressors are widespread (74%) on X and autosomes. I found that a North American X-linked suppressor has distinct effects on SD chromosomes that are from the same population, but bear different inversions. This suggests that SDs might acquire genetic modifiers through chromosomal inversions to escape suppressors.
To ask how meiotic drive shape the structural divergence, I investigated rapid genomic rearrangements on previously unassembled Y chromosomes and centromeric regions among species that diverged just 0.2–2 MYA by combining long-read sequencing and cytological mapping. I discovered two new Y-linked gene families, which amplified more than 40 times on the Y chromosome, and two new centromeric repeats expanded in the D. simulans clade. Intriguingly, similar Y-linked gene families cause male meiotic drive, and expansions of centromeric repeats cause female meiotic drive in other systems. My sequence analyses revealed that potential drivers could arise with massive genomic rearrangements. Together, my results provide evidence of links between rapid genomic rearrangements and the evolution of meiotic drive.
|Advisor:||Larracuente, Amanda M.|
|Commitee:||Blumenstiel, Justin P., Presgraves, Daven C.|
|School:||University of Rochester|
|Department:||School of Arts and Sciences|
|School Location:||United States -- New York|
|Source:||DAI-B 81/11(E), Dissertation Abstracts International|
|Subjects:||Biology, Evolution and Development, Genetics|
|Keywords:||Centromere, Drosophila, Genome evolution, Meiotic drive, Segregation distorter, Y chromosome|
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