Publicação
Natural genetic variation of male sperm size in the nematode Caenorhabditis elegans
| Resumo: | Sperm competition is a major evolutionary force driving diversity in sperm morphology. In Caenorhabditis elegans, an androdioecious nematode, sperm competition may occur between sperm of different males competing for fertilization of a hermaphrodite or between hermaphrodite self-sperm and male sperm. Upon outcrossing, male sperm consistently outcompetes hermaphrodite sperm, and the main factor increasing sperm competitiveness is sperm size, which is always larger in males. Previously observed variation in male sperm size in C. elegans thus potentially reflect adaptive responses to sperm competition. However, the extent of natural genetic variation in male sperm size has not been quantitatively studied and its underlying proximate causes remain elusive. Here we quantitatively assessed natural genetic variation of male sperm size in C. elegans using a world-wide set of 97 wild isolates, covering a maximum of reported genetic variation. The aim of the project was to initiate the genetic characterization of male sperm size using Genome-Wide Association Study (GWAS) and build the basis for future Quantitative Trait Loci (QTL) mapping. This work provides the most extensive analysis of natural genetic variation in C. elegans male sperm size up to date. We report significant heritable variation in male sperm size; however, we did not detect any significant candidate genomic regions using GWAS. Sperm cell area ranging from approximately 16 μm2 to 27 μm2; with most isolates showing an intermediate sperm size of approximately 22 μm2. The analysis detected two isolates as clear outliers: JU561 and LSJ1, which show a much smaller sperm size compared to the rest of isolates. We discuss the significance of these results and outline future approaches. In addition, we report pilot experiments focusing on the effects of male age and mating on sperm size. |
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| Autores principais: | Soares, Nuno Filipe da Silva, 1989- |
| Assunto: | Evolução Variação genética Espermatozóides Nemátodos Teses de mestrado - 2012 |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Sperm competition is a major evolutionary force driving diversity in sperm morphology. In Caenorhabditis elegans, an androdioecious nematode, sperm competition may occur between sperm of different males competing for fertilization of a hermaphrodite or between hermaphrodite self-sperm and male sperm. Upon outcrossing, male sperm consistently outcompetes hermaphrodite sperm, and the main factor increasing sperm competitiveness is sperm size, which is always larger in males. Previously observed variation in male sperm size in C. elegans thus potentially reflect adaptive responses to sperm competition. However, the extent of natural genetic variation in male sperm size has not been quantitatively studied and its underlying proximate causes remain elusive. Here we quantitatively assessed natural genetic variation of male sperm size in C. elegans using a world-wide set of 97 wild isolates, covering a maximum of reported genetic variation. The aim of the project was to initiate the genetic characterization of male sperm size using Genome-Wide Association Study (GWAS) and build the basis for future Quantitative Trait Loci (QTL) mapping. This work provides the most extensive analysis of natural genetic variation in C. elegans male sperm size up to date. We report significant heritable variation in male sperm size; however, we did not detect any significant candidate genomic regions using GWAS. Sperm cell area ranging from approximately 16 μm2 to 27 μm2; with most isolates showing an intermediate sperm size of approximately 22 μm2. The analysis detected two isolates as clear outliers: JU561 and LSJ1, which show a much smaller sperm size compared to the rest of isolates. We discuss the significance of these results and outline future approaches. In addition, we report pilot experiments focusing on the effects of male age and mating on sperm size. |
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