Research summary
Principally, my lab studies recent adaptive radiation -- the evolution of ecological diversity in groups of organisms that are multiplying rapidly. We investigates the ecological forces that drive the rapid origin of new species, that allow them to persist, their wider ecological impacts, and their genetic basis. We carry out field experimental studies of natural selection on genes and phenotypes, behavioral studies on the role of natural and sexual selection in the evolution of reproductive isolation, experiments on interactions between species and their ecological and evolutionary consequences, and genetic studies of adaptive differentiation. At a larger scale we also investigate the evolution of major biodiversity gradients.
My earliest work was carried out on Darwin's famous finches in the Galápagos Islands. Subsequently I worked on finches and other small seed-eating birds of continental regions of Africa and North America. More recently, I and many in my lab have been working on a mini-explosion of new species of threespine sticklebacks in lakes of coastal British Columbia, Canada (my stickleback pages are here). Lab members have also worked on various topics and study systems including: speciation gradients in birds and mammals, range size evolution in primates, ecological speciation in stick insects, mimicry in reef fish and butterflies, and signalling system evtion in electric fishes.
Our research on sticklebacks has had three main directions. The first concerns the role of interactions (competition and predation) in the evolution of differences between species. Our work in this area includes experiments in ponds in which we measure how natural selection on a species is changed when another species (e.g., a competitor) is added to its environment. Recent experiments have also investigated the wider ecosystem consequences of stickleback diversification. The second area concerns the origin and persistence of species themselves, especially the role of ecological selection and reinforcement in the buildup of mating incompatibilities between populations exploiting different environments. The third area, in collaboration with David Kingsley at Stanford University and Katie Peichel at the Fred Hutchinson Cancer Research Center, investigates the genetic basis of species differences.
The question of species persistence has lately taken on a new urgency, with the rapid rate at which the stickleback species pairs are becoming extinct. Part of our work is dedicated to understanding why this is occurring, and what can be done to forestall doom for the species pairs that remain.