The True lab studies the genetic and evolutionary mechanisms underlying phenotypic divergence and speciation using Drosophila species as model organisms. We are particularly interested in male specific pigmentation and behavioral traits, which are rapidly evolving and often species-specific.

We study the evolution of pigmentation patterns from both a developmental genetic and and evolutionary perspective. On the developmental genetic side, we are interested in how proteins function in the dopamine biosynthesis pathway, which produces the precursors for melanin and other body pigments, as well as how these proteins are spatially patterned (prepatterned) to presage adult pigment patterns. On the evolutionary genetic side, we are interested in the genetic architecture of several conspicuous types of pigment pattern variation. First, we are studying the genetics of wing pigmentation differences between Drosophila elegans, which has a male-specific anteriodistal spot, and its sibling species, D. gunungcola, which lacks this spot. These two species also differ in male courtship: D. elegans has a prominent male wing display whereas D. gunungcola lacks this behavioral element. We are using interspecies genetic crosses to elucidate the number and eventual identities of genes involved in divergence in these two traits, as well as to determine whether pleiotropy or close linkage is involved in their coordinated evolution in Asian Drosophila melanogaster group species. Second, we are also studying the molecular genetic basis of a melanic polymorphism in D. elegans: populations from Taiwan and the southern Japanese islands have a dark black body color whereas populations from Indonesia and Southeast Asia have a tan body color. This melanic polymorphism appears to be determined by a single, semidominant autosomal locus. This polymorphism in D. elegans is a powerful model for understanding the molecular genetic basis of insect melanism in general, which is perhaps the most common and widespread form of body color polymorphism in nature.

The True lab also studies how populations of a single species diverge genetically and phenotypically from a biogeographic perspective. The empirical side of this work is being performed using Bahamas and Southeast U.S. populations of Drosophila melanogaster as models. We are interested in determining whether population differentiation occurs with different dynamics in island archipelagos versus mainland and whether dispersal, climatic, or historical patterns are controlling these dynamics. One interrelated set of phenotypes we are concentrating on are male courtship repertoires, which are potentially important factors in prezygotic reproductive isolation during speciation. There are many hypotheses about how these behaviors might evolve in island and peripheral populations but there is very little detailed information on divergence in the wild. We are studying quantitative variation in male courtship in the Bahamas and mainland populations in order to differentiate among these hypotheses. The theoretical side of this work involves simulation and other types of modeling of dispersal behavior and assortative mating and their roles and relative importance in promoting population differentiation and reinforcement of postzygotic reproductive isolation.

We also have broad interests in the microevolutionary mechanisms involved in evolution of developmental systems. Particular foci include the role of cis-regulatory evolution in pattern diversity among closely related species, the involvement of gene co-option in evolutionary novelty, and the potential role of developmental and other types of constraints in the evolution of morphological and ecological traits.