| dc.description | Hybridization is an important factor in the evolution of plants; however, many of the studies which have examined hybrid fitness have been concerned with the study of early generation hybrids. Three studies which examined the fitness consequences of hybridization between two ecotypes of Avena barbata were carried out. The first experiment, which examined the short and long term consequences of hybridization, determined that hybrid vigour which counteracts hybrid breakdown occurs in the F2 generation. Also, although the F6 generation mean is lower than the mid-parent mean, there are individual genotypes within the F6 generation which are capable of outperforming the parental ecotypes. The second experiment examined the fitness of the F6 generation in novel environments, demonstrating that certain genotypes do better under certain environmental conditions and that there are genotypes capable of outperforming the parental ecotypes in all the novel environments tested. The third experiment examined the fitness of early and late generation hybrids in the parental environments, confirming the results of the first experiment which demonstrated the presence of hybrid vigour counteracted by hybrid breakdown in the F2 generation. However, there do not appear to be genotype by environment interactions for fitness. While there are a small number of hybrid genotypes which are capable of outperforming the parental ecotypes in the parental environments, the mesic ecotype outperformed the xeric ecotype in the xeric environment, calling into question whether these ecotypes are locally adapted to their specific environments. Overall, these experiments demonstrated that a single hybridization event can result in a number of outcomes including hybrid vigour, hybrid breakdown, transgessive segregation and genotype by environment interactions. | en_US |
