John R. True, Associate Professor (
Duke University, 1995
Genetics of species differences, speciation
Lab Website: True Lab Website
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
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.