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My dissertation research explores the genetics of hybrid incompatibilities and, separately, the evolution of recombination rates in D. melanogaster and its sibling species.
In Chapter 1, I show that a hybrid lethality factor(s) in the pericentric heterochromatin of the D. mauritiana X chromosome, hybrid lethal on the X (hlx), is incompatible with a factor(s) in the same ∼26-kb autosomal region from both D. sechellia and D. simulans, Suppressor of hlx (Su[hlx] ). By combining genetic and phylogenetic information, I infer that hlx-Su(hlx) hybrid lethality is most likely caused by a derived-ancestral incompatibility.
In Chapter 2, I map a recessive factor to the pericentromeric heterochromatin of the X chromosome in D. simulans and D. mauritiana, heterochromatin hybrid lethal (hhl), that causes lethality in F1 hybrid females with D. melanogaster. Using small segments of the D. melanogaster X chromosome duplicated onto the Y chromosome, I then map a dominant factor that causes hybrid lethality to a small 24-gene region of the D. melanogaster X and provide evidence suggesting that it interacts with hhlmau.
In Chapter 3, I estimate crossover frequencies for seven segments that tile across the euchromatic length of the D. mauritiana X chromosome when introgressed into the genetic backgrounds of D. simulans and D. sechellia. My analyses suggest that both cis- and trans-acting factors contribute to differences in the genetic control of crossover frequencies on the X among the D. simulans clade species.
In Chapter 4, I perform an evolutionary screen of meiotic genes to identify potential candidate genes that might contribute to species differences in the rate of crossing over. I then use a transgenic approach to introduce the D. mauritiana allele of mei-218 into D. melanogaster flies homozygous for a loss-of-function mutation at mei-218 and ask if the D. mauritiana mei-218 allele produces a D. mauritiana-like map in otherwise D. melanogaster flies. I show that the highly divergent meiosis gene, mei-218, is responsible for most of the 1.55-fold phenotypic difference in genetic map length of chromosome 2 between D. melanogaster and D. mauritiana.
Advisor: | Presgraves, Daven C. |
Commitee: | Lambert, David, Orr, Allen, Wittkopp, Patricia |
School: | University of Rochester |
Department: | School of Arts and Sciences |
School Location: | United States -- New York |
Source: | DAI-B 73/09(E), Dissertation Abstracts International |
Source Type: | DISSERTATION |
Subjects: | Genetics, Evolution and Development |
Keywords: | Postzygotic isolation, Recombination rates, Speciation |
Publication Number: | 3508382 |
ISBN: | 978-1-267-34096-2 |