A maladaptive combination of traits contributes to the maintenance of a stable hybrid zone between two divergent species of Drosophila
| Autor: | W. Thurston Nash, Aaron A. Comeault, Daniel R. Matute, Brandon S. Cooper, Alisa Sedghifar |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
0303 health sciences biology Ecology Introgression Ecotone 15. Life on land biology.organism_classification 010603 evolutionary biology 01 natural sciences Gene flow 03 medical and health sciences Hybrid zone Habitat Evolutionary biology Clade Drosophila 030304 developmental biology Hybrid |
| DOI: | 10.1101/138388 |
| Popis: | Geographical areas where two species come into contact and hybridize serve as natural laboratories for assessing mechanisms that limit gene flow between species. The ranges of about half of all closely relatedDrosophilaspecies overlap, and the genomes of several pairs reveal signatures of past introgression. However, only two contemporary hybrid zones have been characterized in the genus, and both are recently diverged sister species (D. simulans-D. sechellia, Ks = 0.05;D. yakuba-D. santomea, Ks = 0.048). Here we present evidence of a new hybrid zone, and the ecological mechanisms that maintain it, between two highly divergentDrosophilaspecies (Ks = 0.11). On the island of Bioko in west Africa,D. teissierioccupies mostly forests,D. yakubaoccupies mostly open agricultural areas, and recently, we discovered that hybrids between these species occur near the interface of these habitats. Genome sequencing revealed that all field-sampled hybrids are F1progeny ofD. yakubafemales andD. teissierimales. We found no evidence for either advanced-generation hybrids or F1hybrids produced byD. teissierifemales andD.yakubamales. The lack of advanced-generation hybrids on Bioko is consistent with mark-recapture and laboratory experiments that we conducted, which indicate hybrids have a maladaptive combination of traits. LikeD. yakuba, hybrids behaviorally prefer open habitat that is relatively warm and dry, but likeD. teissieri, hybrids have low desiccation tolerance, which we predict leaves them physiologically ill-equipped to cope with their preferred habitat. These observations are consistent with recent findings of limited introgression in theD. yakubaclade and identify an ecological mechanism for limiting gene flow betweenD. yakubaandD. teissieri; namely, selection against hybrids that we have documented, in combination with hybrid male sterility, contributes to the maintenance of this narrow (~30m), stable hybrid zone centered on the forest-open habitat ecotone. Our results show how a deleterious combination of parental traits can result in unfit or maladapted hybrids. |
| Databáze: | OpenAIRE |
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