Reconstructing Patterns of Diversification in Neodiprion Sawflies: A Test of the Sympatric Host Race Formation HypothesisEPA Grant Number: FP916309
Title: Reconstructing Patterns of Diversification in Neodiprion Sawflies: A Test of the Sympatric Host Race Formation Hypothesis
Investigators: Linnen, Catherine R.
Institution: Harvard Graduate School of Arts and Science
EPA Project Officer: Carleton, James N
Project Period: January 1, 2004 through December 31, 2006
Project Amount: $83,126
RFA: STAR Graduate Fellowships (2004) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Biology/Life Sciences , Fellowship - Entomology
This project investigates 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 objective 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 test the hypothesis that Neodiprion has diversified primarily by shifting to novel host plants in sympatry.
The hypothesis that sympatric host shifts have generated the diversity of Neodiprion sawflies generates the simple prediction that sister species will occur sympatrically on different host plants. Therefore, testing this hypothesis will require analyses of geographical ranges and host use patterns of Neodiprion species in light of their evolutionary relationships. Specimens of Neodiprion species have been collected throughout North America, and a robust phylogenetic estimate for the genus will be obtained by examining interspecific variation in DNA sequence data (using both mitochondrial and nuclear loci). Species’ ranges and host use patterns will be elucidated from locality and host use data from the literature and from museum collections throughout North America.