A grant has been awarded to Dr. Brian Farrell and Ms. Catherine Linnen at Harvard University to investigate the ecological and geographical circumstances under which new species arise. In particular, evolutionary biologists have long debated whether geographic barriers to reproduction are required for species formation. There is now convincing evidence that in plant-feeding insects, new species can arise in the absence of geographical barriers to reproduction (i.e., in sympatry) when individuals shift to a new host plant. But the role that this speciation mode has played in generating the staggering diversity of plant-feeding insects remains untested, as most studies have focused on single diverging or recently diverged species. The goal of this research is to understand the contribution that different speciation modes have made to contemporary diversity and to determine whether certain life history attributes (e.g., herbivory and dietary specialization) predispose organisms to particular speciation modes. These questions will be addressed in the sawfly genus Neodiprion (Hymenoptera: Diprionidae), a group of North American conifer-feeding insects that includes several pest species. Specifically, this study will elucidate the evolutionary relationships between species in the genus Neodiprion by examining interspecific variation in DNA sequences and morphological characteristics.
The results of this study will provide important insights into the fundamental biological question: How and why do new species form? In addition, this research will contribute to our understanding of native and invasive species of Neodiprion and may uncover cryptic, host-specialized species within the genus. Upon completion of these studies, a database including museum specimens, publications, life history information, geographic range, and digital images for each Neodiprion species will be made publicly available via the World Wide Web.
