The evolution, ecology and genetics of sex determination in Mercurialis annua
<p>The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which...
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| Format: | Thesis |
| Language: | English |
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2012
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| _version_ | 1797092799941705728 |
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| author | Russell, JRW |
| author2 | Pannell, J |
| author_facet | Pannell, J Russell, JRW |
| author_sort | Russell, JRW |
| collection | OXFORD |
| description | <p>The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which control it are surprisingly diverse. In this thesis, I examine sex determination in the plant species Mercurialis annua L. (Euphorbiaceae). I assess the mechanism of sex determination operating in dioecious and androdioecious populations of M. annua and also investigate the conservation and evolution of sex-determining mechanisms across the annual mercury clade, the lineages of which display exceptional variation in sexual system.</p> <p>First, using crosses, I establish that sex in dioecious M. annua is controlled by a single-locus genetic mechanism, consistent with recent work that identified a single male-linked DNA marker in the species. My search for new sex-linked genes revealed none, however, suggesting that M. annua possesses at most a small non-recombining region around sex-determining loci. Why many dioecious plants lack heteromorphic sex chromosomes is still poorly understood and I consider explanations for this. I extend my investigation by comparing genetic diversity between loci that differ in their linkage to the sex-determining locus. I find a single male-linked marker to possess significantly lower diversity than autosomal loci, but no difference in the diversity of partially sex-linked and non-sex-linked genes.</p> <p>I also assess the conservation of a sex-linked marker among annual mercury lineages and conduct crosses between lineages to examine the conservation of sex determination. My findings indicate a conserved mechanism of single-locus genetic sex determination and I consider the role polyploidisation and hybridisation have played in sexual system evolution and the modification of sex-determining mechanisms in the clade. Finally, I assess the presence of environmental sex determination in androdioecious M. annua, concluding that although male frequency is not influenced by growing density, a degree of sexual lability exists in the lineage.</p> |
| first_indexed | 2024-03-07T03:51:11Z |
| format | Thesis |
| id | oxford-uuid:c15091c5-1d01-47cc-93bd-036bc46b42a9 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:51:11Z |
| publishDate | 2012 |
| record_format | dspace |
| spelling | oxford-uuid:c15091c5-1d01-47cc-93bd-036bc46b42a92022-03-27T06:00:46ZThe evolution, ecology and genetics of sex determination in Mercurialis annuaThesishttp://purl.org/coar/resource_type/c_db06uuid:c15091c5-1d01-47cc-93bd-036bc46b42a9Plant SciencesBiologyGenetics (life sciences)Evolution,ecology and systematicsEnglishOxford University Research Archive - Valet2012Russell, JRWPannell, JFilatov, D<p>The allocation of resources to male or female progeny, or to male or female reproductive function more generally, is one of the most important life history decisions a sexually reproducing individual must ever make. Sex determination is thus a fundamental process, yet the mechanisms which control it are surprisingly diverse. In this thesis, I examine sex determination in the plant species Mercurialis annua L. (Euphorbiaceae). I assess the mechanism of sex determination operating in dioecious and androdioecious populations of M. annua and also investigate the conservation and evolution of sex-determining mechanisms across the annual mercury clade, the lineages of which display exceptional variation in sexual system.</p> <p>First, using crosses, I establish that sex in dioecious M. annua is controlled by a single-locus genetic mechanism, consistent with recent work that identified a single male-linked DNA marker in the species. My search for new sex-linked genes revealed none, however, suggesting that M. annua possesses at most a small non-recombining region around sex-determining loci. Why many dioecious plants lack heteromorphic sex chromosomes is still poorly understood and I consider explanations for this. I extend my investigation by comparing genetic diversity between loci that differ in their linkage to the sex-determining locus. I find a single male-linked marker to possess significantly lower diversity than autosomal loci, but no difference in the diversity of partially sex-linked and non-sex-linked genes.</p> <p>I also assess the conservation of a sex-linked marker among annual mercury lineages and conduct crosses between lineages to examine the conservation of sex determination. My findings indicate a conserved mechanism of single-locus genetic sex determination and I consider the role polyploidisation and hybridisation have played in sexual system evolution and the modification of sex-determining mechanisms in the clade. Finally, I assess the presence of environmental sex determination in androdioecious M. annua, concluding that although male frequency is not influenced by growing density, a degree of sexual lability exists in the lineage.</p> |
| spellingShingle | Plant Sciences Biology Genetics (life sciences) Evolution,ecology and systematics Russell, JRW The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title | The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title_full | The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title_fullStr | The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title_full_unstemmed | The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title_short | The evolution, ecology and genetics of sex determination in Mercurialis annua |
| title_sort | evolution ecology and genetics of sex determination in mercurialis annua |
| topic | Plant Sciences Biology Genetics (life sciences) Evolution,ecology and systematics |
| work_keys_str_mv | AT russelljrw theevolutionecologyandgeneticsofsexdeterminationinmercurialisannua AT russelljrw evolutionecologyandgeneticsofsexdeterminationinmercurialisannua |