Dissertation Research: Phylogenetics and Resource Specialization in the Seed Beetle Genus Stator (Coleoptera: Chrysomelidae: Bruchinae)

Harvard University, Cambridge MA

Investigators

Abstract

0073330 Farrell and Morse Most herbivorous insects feed on only one or very few kinds of hostplants, despite the apparent advantages of being able to use multiple hosts when foodplants are scarce in space or time. Ecological research has generated considerable insight into the generation and maintenance of this specialization, but the long term persistence and consequences of variation in diet breadth are poorly understood. For example, is specialization a dead end? There is less evidence on how or even whether the process of specialization within populations of generalist species is connected to speciation and specialist species. Research by graduate student Geoffrey Morse, under the direction of Dr. Brian Farrell, will use DNA sequence data to: (1) reconstruct the phylogeny of the seed beetle genus Stator (family Bruchidae); and (2) examine the genetic relationships of populations of the sister species S. limbatus Horn (a generalist seed predator) and S. beali Johnson (a specialist feeder). The first aspect will test hypotheses concerning the evolutionary consequences of changes in resource specialization. The second aspect will test hypotheses concerning both the nature of speciation in phytophagous insects, and the population genetic correlates of divergence in diet breadth. Insights into how insects become specialists or generalists, as well as into the evolutionary consequences of these different habits, have implications for fields as diverse as evolutionary biology, conservation biology, and agricultural entomology. By providing an explicit historical perspective on the evolutionary ecology of host use in Stator, this research will contribute to the synthesis between ecological and evolutionary explanations of diversity and resource use.