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John R. True, Associate Professor (CV)

Ph.D., Duke University, 1995

Genetics of species differences, speciation


Office: LS114

Phone:  (631)632-8600

Lab Website: True Lab Website

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Research Summary:

My lab group is interested in the genetic and developmental basis of differences among closely related species and how natural and sexual selection bring these differences about. Our work centers on Drosophila melanin patterning as a genetic and developmental model system.

The laboratory is currently studying the evolutionary genetics of melanin patterning and male courtship behavior in the Oriental melanogaster species group. Several lineages in this species group exhibit male specific wing spots (Fig. 1). A recent phylogenetic analysis (Fig. 2) indicates that multiple gains or losses of male wing spots have occurred during the Oriental species group radiation. Intriguingly, species with the male wing spots also exhibit a striking wing display during male courtship. [To view a video of courtship in Drosophila elegans, in which much of our current work is focused, go movie page] D. elegans males also appear to use this display in male-male aggressive interactions [movie page]. Species that do not have male wing spots do not exhibit this behavior. We are currently surveying male courtship behavior throughout the Oriental melanogaster species group in order to understand how this novel behavior has evolved. For example, we would like to know whether the use of the male wing display in courtship evolved before or after its use in male-male interaction and whether specific elements in male courtship, such as circling the female, were prerequisites for evolution of the male wing display.

We are also studying the molecular genetic basis for naturally occurring melanism in D. elegans (Fig. 3). Populations of D. elegans from the northern part of its range (Taiwan, Japan) are dark black in color whereas southern populations (China, SE Asia, Indonesia) are light tan in color. This morph difference is controlled by a single, semidominant, autosomal Mendelian factor. We are in the process of fine-scale mapping of this locus with the ultimate aim of characterizing it at the molecular level. Melanic polymorphisms like this one in D. elegans are extremely common and insects but in no case has such a polymorphism been identified at the molecular level. Identifying the gene responsible for melanism in D. elegans will provide a crucial model for a general understanding of insect melanism at the developmental, genetic, and ecological levels.