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 | Research Interests |  |
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| The genetic basis of ecotypic differentiation in Australian Senecio |
| | We are currently exploring various aspects of ecological divergence in Senecio pinnatifolius inhabiting contrasting habitats along the east coast of Australia. Ecotypes of this species exhibit high levels of neutral gene flow yet they are morphologically different and survive poorly in alternative habitats. We want to know what is the genetic basis of this ecological divergence and whether it has led to the emergence of typical reproductive barriers to gene flow like pollen sterility and plant inviability. |
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| Genetic mechanisms controlling hybrid fitness in sunflowers |
| | For the last two years, using both field and laboratory experiments, we have investigated this issue in the hybridizing sunflowers Helianthus annuus and H. petiolaris. We have found that ecological selection acting on the cytoplasm of these species maintains genetic incompatibilities between cytoplasmic (e.g., mitochondria, chloroplast, or imprinting mechanisms) and nuclear components of the two species. Similarly, the cytoplasm appears to control many of the traits that define sunflower species identity. We are currently investigating the genetic basis of this failed evolutionary dialogue between the nucleus and the cytoplasm. |
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| Gametic interactions and the origin of new species |
| | Gametes interact, combine their genomes, and produce a new organism. Ho do they recognize each other? Do these interactions diverge easily? If so, what are the forces driving gametic interactions divergence? Do these interactions contribute to the origin of new species? We are investigating some of these question in flowering plants. Although some partial answers have been provided in other systems, we still remain ignorant as to the contributions of sexual selection, for instance, to plant diversification. We are currently exploring how rapidly reproduction-related genes evolve in plants, the genetic basis of pollen competition within and between species, and how flower morphology affects crossability between related species. |
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| Reinforcement |
| | Reinforcement occurs when natural selection strengthens reproductive barriers in response to maladaptive hybridization. A formidably polemical idea, selection now has been shown to reinforce divergence in diverse taxa (e.g., frogs, birds, flies, trees), and in a variety of ways. Despite theoretical and empirical advances we still lack detailed knowledge about the genetics underlying reinforcement. Studying Drosophila pseudoobscura, I found several genomic regions, some of them containing as few as five genes, enhancing interspecies female mating discrimination. Furthermore, I found that some of these genomic regions enhance female mating discrimination in both D. pseudoobscura and its sibling hybridizing species D. persimilis, suggesting that reinforcement might occur via one-allele assortative mating models. Currently we are investigating a putative case of reinforcement in sunflowers. |
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