The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it>
<p>Abstract</p> <p>Background</p> <p>The cosmopolitan freshwater snail <it>Physa acuta </it>has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that <it&g...
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BMC
2011-05-01
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| Series: | BMC Evolutionary Biology |
| Online Access: | http://www.biomedcentral.com/1471-2148/11/144 |
| _version_ | 1818907047314325504 |
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| author | Lydeard Charles Wethington Amy R Dillon Robert T |
| author_facet | Lydeard Charles Wethington Amy R Dillon Robert T |
| author_sort | Lydeard Charles |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>The cosmopolitan freshwater snail <it>Physa acuta </it>has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that <it>Physa carolinae</it>, recently described from the American southeast, is a sister species of <it>P. acuta</it>. The divergence of the <it>acuta/carolinae </it>ancestor from the more widespread <it>P. pomilia </it>appears to be somewhat older, and the split between a hypothetical <it>acuta/carolinae/pomilia </it>ancestor and <it>P. gyrina </it>appears older still.</p> <p>Results</p> <p>Here we report the results of no-choice mating experiments yielding no evidence of hybridization between <it>gyrina </it>and any of four other populations (<it>pomilia, carolinae</it>, Philadelphia <it>acuta</it>, or Charleston <it>acuta</it>), nor between <it>pomilia </it>and <it>carolinae</it>. Crosses between <it>pomilia </it>and both <it>acuta </it>populations yielded sterile F1 progeny with reduced viability, while crosses between <it>carolinae </it>and both <it>acuta </it>populations yielded sterile F1 hybrids of normal viability. A set of mate-choice tests also revealed significant sexual isolation between <it>gyrina </it>and all four of our other <it>Physa </it>populations, between <it>pomilia </it>and <it>carolinae</it>, and between <it>pomilia </it>and Charleston <it>acuta</it>, but not between <it>pomilia </it>and the <it>acuta </it>population from Philadelphia, nor between <it>carolinae </it>and either <it>acuta </it>population. These observations are consistent with the origin of hybrid sterility prior to hybrid inviability, and a hypothesis that speciation between <it>pomilia </it>and <it>acuta </it>may have been reinforced by selection for prezygotic reproductive isolation in sympatry.</p> <p>Conclusions</p> <p>We propose a two-factor model for the evolution of postzygotic reproductive incompatibility in this set of five <it>Physa </it>populations consistent with the Dobzhansky-Muller model of speciation, and a second two-factor model for the evolution of sexual incompatibility. Under these models, species trees may be said to correspond with gene trees in American populations of the freshwater snail, <it>Physa</it>.</p> |
| first_indexed | 2024-12-19T21:48:54Z |
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| id | doaj.art-2e53ece377934a5fa3a896536a1ad6c4 |
| institution | Directory Open Access Journal |
| issn | 1471-2148 |
| language | English |
| last_indexed | 2024-12-19T21:48:54Z |
| publishDate | 2011-05-01 |
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| spelling | doaj.art-2e53ece377934a5fa3a896536a1ad6c42022-12-21T20:04:27ZengBMCBMC Evolutionary Biology1471-21482011-05-0111114410.1186/1471-2148-11-144The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it>Lydeard CharlesWethington Amy RDillon Robert T<p>Abstract</p> <p>Background</p> <p>The cosmopolitan freshwater snail <it>Physa acuta </it>has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that <it>Physa carolinae</it>, recently described from the American southeast, is a sister species of <it>P. acuta</it>. The divergence of the <it>acuta/carolinae </it>ancestor from the more widespread <it>P. pomilia </it>appears to be somewhat older, and the split between a hypothetical <it>acuta/carolinae/pomilia </it>ancestor and <it>P. gyrina </it>appears older still.</p> <p>Results</p> <p>Here we report the results of no-choice mating experiments yielding no evidence of hybridization between <it>gyrina </it>and any of four other populations (<it>pomilia, carolinae</it>, Philadelphia <it>acuta</it>, or Charleston <it>acuta</it>), nor between <it>pomilia </it>and <it>carolinae</it>. Crosses between <it>pomilia </it>and both <it>acuta </it>populations yielded sterile F1 progeny with reduced viability, while crosses between <it>carolinae </it>and both <it>acuta </it>populations yielded sterile F1 hybrids of normal viability. A set of mate-choice tests also revealed significant sexual isolation between <it>gyrina </it>and all four of our other <it>Physa </it>populations, between <it>pomilia </it>and <it>carolinae</it>, and between <it>pomilia </it>and Charleston <it>acuta</it>, but not between <it>pomilia </it>and the <it>acuta </it>population from Philadelphia, nor between <it>carolinae </it>and either <it>acuta </it>population. These observations are consistent with the origin of hybrid sterility prior to hybrid inviability, and a hypothesis that speciation between <it>pomilia </it>and <it>acuta </it>may have been reinforced by selection for prezygotic reproductive isolation in sympatry.</p> <p>Conclusions</p> <p>We propose a two-factor model for the evolution of postzygotic reproductive incompatibility in this set of five <it>Physa </it>populations consistent with the Dobzhansky-Muller model of speciation, and a second two-factor model for the evolution of sexual incompatibility. Under these models, species trees may be said to correspond with gene trees in American populations of the freshwater snail, <it>Physa</it>.</p>http://www.biomedcentral.com/1471-2148/11/144 |
| spellingShingle | Lydeard Charles Wethington Amy R Dillon Robert T The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> BMC Evolutionary Biology |
| title | The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> |
| title_full | The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> |
| title_fullStr | The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> |
| title_full_unstemmed | The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> |
| title_short | The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail <it>Physa</it> |
| title_sort | evolution of reproductive isolation in a simultaneous hermaphrodite the freshwater snail it physa it |
| url | http://www.biomedcentral.com/1471-2148/11/144 |
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