Theory predicts that sexual reproduction confers an advantage over asexual reproduction due to the generation and maintenance of genetic variation afforded by the processes of recombination and segregation. However, this prediction has rarely been empirically tested. Oenothera is a flowering plant genus whose evolutionary history is punctuated with numerous transitions from sexual reproduction to a form of functionally asexual reproduction known as Permanent Translocation Heterozygosity (PTH). In Ch. 2, a greenhouse experiment examined patterns of phenotypic and genetic variation within and between populations across eight Oenothera species, representing four independent transitions to PTH. I found some evidence for a decrease in heritability and an increase in population differentiation in phenotypic traits associated with the loss of sex. Ch. 3 explored the possibility that rare outcrossing events represent a mechanism for the maintenance of variation in a PTH species. Analysis of microsatellite markers showed evidence for extremely low rates of outcrossing in natural populations (< 1%) of O. biennis, a PTH species.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/44022 |
| Date | 18 March 2014 |
| Creators | Godfrey, Ryan |
| Contributors | Johnson, Marc |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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