Publicação
Are reproductive barriers involved in the maintenance of a latitudinal cline?: insights from a set of populations of Drosophila subobscura adapting to a common environment
| Resumo: | Speciation results from the evolution of reproductive isolation between populations. Reproductive barriers can evolve as a direct product of local adaptation, in which individuals discriminate to avoid less fit progeny, or as a by-product of such adaptation. Drosophila subobscura possesses fascinating latitudinal clines for several quantitative traits. However the neutral genetic differentiation among populations is low. Therefore, the maintenance of such clines suggests that reproductive barriers exist between populations. The main goal of the present work was to test whether reproductive barriers between populations from two extremes of the cline exist and, if so, if they decrease or increase over time when these populations invade a new common environment. For that we founded two populations of Drosophila subobscura from Adraga (Portugal) and Groningen (Netherlands). First, the initial differentiation and early adaptation in life-history traits of both populations were characterized. We found that during the first 11 generations the populations showed differences in several life-history traits. However, in general, the populations of both foundations did not exhibit temporal changes across generations. As for the reproductive barriers we found that at an early (fifth) generation, both populations demonstrated a (marginally significant) preference for assortative mating. However, hybrid breakdown was not detected among populations. Five generations later, assortative mating faded away, indicating a relaxation of the selective pressures in the new environment. This study was important as it suggests that, while pre-zygotic barriers may play a role in the maintenance of a latitudinal cline, they fade away quickly during adaptation in a novel, common environment. The study also revealed the need to add a temporal component to studies of reproductive isolation. |
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| Autores principais: | Bárbaro, Ana Margarida dos Santos, 1988- |
| Assunto: | Evolução Genética das populações Reprodução Latitude Drosophila subobscura Adraga - Portugal Groningen - Holanda Teses de mestrado - 2011 |
| Ano: | 2011 |
| 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: | Speciation results from the evolution of reproductive isolation between populations. Reproductive barriers can evolve as a direct product of local adaptation, in which individuals discriminate to avoid less fit progeny, or as a by-product of such adaptation. Drosophila subobscura possesses fascinating latitudinal clines for several quantitative traits. However the neutral genetic differentiation among populations is low. Therefore, the maintenance of such clines suggests that reproductive barriers exist between populations. The main goal of the present work was to test whether reproductive barriers between populations from two extremes of the cline exist and, if so, if they decrease or increase over time when these populations invade a new common environment. For that we founded two populations of Drosophila subobscura from Adraga (Portugal) and Groningen (Netherlands). First, the initial differentiation and early adaptation in life-history traits of both populations were characterized. We found that during the first 11 generations the populations showed differences in several life-history traits. However, in general, the populations of both foundations did not exhibit temporal changes across generations. As for the reproductive barriers we found that at an early (fifth) generation, both populations demonstrated a (marginally significant) preference for assortative mating. However, hybrid breakdown was not detected among populations. Five generations later, assortative mating faded away, indicating a relaxation of the selective pressures in the new environment. This study was important as it suggests that, while pre-zygotic barriers may play a role in the maintenance of a latitudinal cline, they fade away quickly during adaptation in a novel, common environment. The study also revealed the need to add a temporal component to studies of reproductive isolation. |
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