Floral Phenotypic Integration of Eight Brassicaceae Species from Native and Non-native Environments
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By studying the co-variation of traits that are functionally and genetically linked in organisms that are closely related, or by comparing patterns of integration between populations with different ecologies, we can better understand the evolution of the whole organism phenotype. In the following study, I addressed how populations with different ecological histories differ in patterns of phenotypic integration in floral form by examining a set of native and non-native populations. I examined six closely related Brassica species, and two species of Raphanus to investigate the signal of shared ancestry on patterns of integration. Rarely have patterns of integration been examined through floral development, and here I demonstrated that changes in phenotype in the Brassicaceae do indeed occur across native and non-native environments, through developmental time, and across parental and hybrid taxa. Accounting for all the trait measurements taken in the study, the significant trait correlations between both short filament and long filament, and style length and ovary length are the only trait correlations that remain constant across all species and both origins. Overall, the functional hypothesis that the native origin would be more highly integrated than the non-native origin was upheld. In contrast to the functional hypothesis that hybrid Brassicaceae would be more highly integrated than their parental species, neither diploid nor polyploid species (as a group) were more highly correlated than the other in my data set. My results give further evidence for allopolyploid phenotypes exceeding diploid parents in level of integration for B. carinata . While there are many more questions regarding the evolution of complex phenotypes, my study with the Brassicaceae provides further insights into questions that remain from past research in the area of floral phenotypic integration.