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Title: Inbreeding avoidance and the genetic basis of inbreeding depression in Drosophila
Author: Ferreira, Álvaro Gil Araújo
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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This dissertation describes a study of the role of sexual selection in inbreeding avoidance and an extensive analysis of the genetics basis of inbreeding depression using species of the fruit fly Drosophila as model organisms. Using behaviour experiments and molecular genetic techniques I investigated the role of both female mate choice and polyandry in inbreeding avoidance. My results show that in the four Drosophila species analysed (D. melanogaster, D. simulans, D. subobscura and D. littoralis) female flies are not able to avoid inbreeding through mate choice. However, when polyandry was investigated in D. melanogaster and in D. littoralis I found that post-copulatory mechanisms can contribute to inbreeding avoidance. Specifically, females sometimes appear preferentially to use sperm from an unrelated rather than related partner. However, the pattern is complicated and the exact outcome appears to depend on the species, the remating frequency and on male mating order. Concerning inbreeding depression, two main genetic mechanisms have been invoked to explain the deleterious effects associated with inbreeding, one based on the exposure of deleterious recessive alleles and the other on heterozygote advantage. In order to investigate the relative importance of these two mechanisms, I analysed the relationship between heterozygosity at microsatellite markers and fitness in D. melanogaster, comparing inbred and outbred crosses under benign and stressed conditions. It was found that although the effects of deleterious recessive alleles have a significant effect, heterozygote advantage also plays an important role on inbreeding depression. Additionally, I show that the deleterious effects of inbreeding are at least partly environmental-specific.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available