Molecular evolution of Drosophila Sex-lethal and related sex determining genes
<p>Abstract</p> <p>Background</p> <p>Sex determining mechanisms are evolutionarily labile and related species often use different primary signals and gene regulatory networks. This is well illustrated by the sex determining cascade of <it>Drosophila </it>fru...
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| Format: | Article |
| Language: | English |
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BMC
2012-01-01
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| Series: | BMC Evolutionary Biology |
| Online Access: | http://www.biomedcentral.com/1471-2148/12/5 |
| _version_ | 1818890882792816640 |
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| author | Mullon Charles Pomiankowski Andrew Reuter Max |
| author_facet | Mullon Charles Pomiankowski Andrew Reuter Max |
| author_sort | Mullon Charles |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Sex determining mechanisms are evolutionarily labile and related species often use different primary signals and gene regulatory networks. This is well illustrated by the sex determining cascade of <it>Drosophila </it>fruitflies, which have recruited <it>Sex-lethal </it>as the master switch and cellular memory of sexual identity, a role performed in other insects by the gene <it>transformer</it>. Here we investigate the evolutionary change in the coding sequences of sex determining genes associated with the recruitment of <it>Sex-lethal</it>. We analyze sequences of <it>Sex-lethal </it>itself, its <it>Drosophila </it>paralogue <it>sister-or-Sex-lethal </it>and downstream targets <it>transformer </it>and <it>doublesex</it>.</p> <p>Results</p> <p>We find that the recruitment of <it>sister-or-Sex-lethal </it>was associated with a number of adaptive amino acid substitutions, followed by a tightening of purifying selection within the <it>Drosophila </it>clade. Sequences of the paralogue <it>sister-or-Sex-lethal</it>, in contrast, show a signature of rampant positive selection and relaxation of purifying selection. The recruitment of <it>Sex-lethal </it>as top regulator and memory gene is associated with a significant release from purifying selection in <it>transformer </it>throughout the <it>Drosophila </it>clade. In addition, <it>doublesex </it>shows a signature of positive selection and relaxation of purifying selection in the <it>Drosophila </it>clade. A similar pattern is seen in sequences from the sister Tephritidae clade.</p> <p>Conclusions</p> <p>The pattern of molecular evolution we observe for <it>Sex-lethal </it>and its paralogue <it>sister-or-Sex-lethal </it>is not characteristic of a duplication followed by neo-functionalization. Rather, evidence suggests a sub-functionalization scenario achieved through the evolution of sophisticated splicing. As expected, we find that <it>transformer </it>evolves under relaxed purifying selection after the recruitment of <it>Sex-lethal </it>in <it>Drosophila</it>. Finally, the observation of <it>doublesex </it>adaptation in both <it>Drosophila </it>and Tephritidae suggests that these changes are due to ongoing adaptation of downstream sex-specific regulation, rather than being associated the recruitment of <it>Sex-lethal </it>and the resulting change in the topology of the sex determining cascade.</p> |
| first_indexed | 2024-12-19T17:31:59Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-19T17:31:59Z |
| publishDate | 2012-01-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Evolutionary Biology |
| spelling | doaj.art-fa22e0f431a041d4a2938079d6217bff2022-12-21T20:12:26ZengBMCBMC Evolutionary Biology1471-21482012-01-01121510.1186/1471-2148-12-5Molecular evolution of Drosophila Sex-lethal and related sex determining genesMullon CharlesPomiankowski AndrewReuter Max<p>Abstract</p> <p>Background</p> <p>Sex determining mechanisms are evolutionarily labile and related species often use different primary signals and gene regulatory networks. This is well illustrated by the sex determining cascade of <it>Drosophila </it>fruitflies, which have recruited <it>Sex-lethal </it>as the master switch and cellular memory of sexual identity, a role performed in other insects by the gene <it>transformer</it>. Here we investigate the evolutionary change in the coding sequences of sex determining genes associated with the recruitment of <it>Sex-lethal</it>. We analyze sequences of <it>Sex-lethal </it>itself, its <it>Drosophila </it>paralogue <it>sister-or-Sex-lethal </it>and downstream targets <it>transformer </it>and <it>doublesex</it>.</p> <p>Results</p> <p>We find that the recruitment of <it>sister-or-Sex-lethal </it>was associated with a number of adaptive amino acid substitutions, followed by a tightening of purifying selection within the <it>Drosophila </it>clade. Sequences of the paralogue <it>sister-or-Sex-lethal</it>, in contrast, show a signature of rampant positive selection and relaxation of purifying selection. The recruitment of <it>Sex-lethal </it>as top regulator and memory gene is associated with a significant release from purifying selection in <it>transformer </it>throughout the <it>Drosophila </it>clade. In addition, <it>doublesex </it>shows a signature of positive selection and relaxation of purifying selection in the <it>Drosophila </it>clade. A similar pattern is seen in sequences from the sister Tephritidae clade.</p> <p>Conclusions</p> <p>The pattern of molecular evolution we observe for <it>Sex-lethal </it>and its paralogue <it>sister-or-Sex-lethal </it>is not characteristic of a duplication followed by neo-functionalization. Rather, evidence suggests a sub-functionalization scenario achieved through the evolution of sophisticated splicing. As expected, we find that <it>transformer </it>evolves under relaxed purifying selection after the recruitment of <it>Sex-lethal </it>in <it>Drosophila</it>. Finally, the observation of <it>doublesex </it>adaptation in both <it>Drosophila </it>and Tephritidae suggests that these changes are due to ongoing adaptation of downstream sex-specific regulation, rather than being associated the recruitment of <it>Sex-lethal </it>and the resulting change in the topology of the sex determining cascade.</p>http://www.biomedcentral.com/1471-2148/12/5 |
| spellingShingle | Mullon Charles Pomiankowski Andrew Reuter Max Molecular evolution of Drosophila Sex-lethal and related sex determining genes BMC Evolutionary Biology |
| title | Molecular evolution of Drosophila Sex-lethal and related sex determining genes |
| title_full | Molecular evolution of Drosophila Sex-lethal and related sex determining genes |
| title_fullStr | Molecular evolution of Drosophila Sex-lethal and related sex determining genes |
| title_full_unstemmed | Molecular evolution of Drosophila Sex-lethal and related sex determining genes |
| title_short | Molecular evolution of Drosophila Sex-lethal and related sex determining genes |
| title_sort | molecular evolution of drosophila sex lethal and related sex determining genes |
| url | http://www.biomedcentral.com/1471-2148/12/5 |
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