Grant: Discovery Grants Program - Individual

My broad objectives are to (a) understand the biogeographic history of insects at a time when continents were not in the positions they occupy now, and (b) to determine the evolutionary significance of morphological traits commonly used in defining their taxonomic categories. Members of the grasshopper family Acrididae are notable for their widespread distributions and rich phenotypic diversities, and are therefore suitable for addressing those themes. Earlier biogeographic studies lacked methodological rigour and were essentially ""narratives"", ad hoc interpretations of the distribution, relative abundance and morphology of present-day species. Such accounts have, up to now, gone untested. Since my last instalment, our molecular phylogenetic analyses of mitochondrial DNA sequences have shed some light on the biogeographic origins of 3 subfamilies. For instance, we show that the melanopline grasshoppers constitute one of a few examples of an early South to North America dispersal, a direction and timeframe that are contrary to what was previously thought. Preliminary results suggest that another group, the gomphocerine grasshoppers, may also have originated in one of the southern continents, but at the moment we do not know which land mass. To address the latter and other questions arising from recent work, I propose to expand our analyses in three ways. First, for collaborative purposes, we will analyze nuclear DNA sequences. Second, we will sample species from areas (e.g. Africa, South America, Southeast Asia) which heretofore, have been underrepresented in our studies but whose analysis will be critical to addressing unresolved questions of origin. Third, we intend to initiate similar studies of other subfamilies with intercontinental distributions to determine how general are our biogeographic findings. Ultimately, it is expected that this research will contribute to the growing body of empirical studies that seek to understand the early biogeographic history of insects. Our phylogenies are also expected to provide templates for understanding the evolution of acoustic and visual displays and of genitalic characters, traits that undoubtedly have played a role in the diversification of these insects.