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Peter R. Grant and B. Rosemary Grant
Emeritus Professors, Princeton University
Title: In Search of The Causes of Evolution: Darwin’s Finches on Galápagos
Host: Losos Lab
Reception following event
Abstract: More than 14 species of Darwin’s finches evolved from a common ancestor in the Galápagos archipelago in the last two million years. Although this iconic adaptive radiation happened in the past, we have sought an understanding of the causes through studies of contemporary populations. A long-term study of four species on the small island of Daphne Major has shown natural selection and introgressive hybridization to be key processes. Directional selection on ecologically significant morphological traits such as beak size and body size occurs moderately frequently when the environment changes. Species hybridize, rarely, and exchange genes because under favorable conditions the hybrids are as fit as the parental species that gave rise to them. Depending on circumstances, introgression can either cause two species to collapse to one or leads to the formation of a new species. The latest, current, phase of research is designed to investigate the radiation at molecular genetic level.
Bio: Peter and Rosemary Grant have been studying Darwin’s finches on the Galápagos islands since 1973. The fieldwork is designed to understand the causes of an adaptive radiation. It combines analyses of archipelago-wide patterns of evolution with detailed investigations of population level processes on two islands, Genovesa and Daphne. The work is a blend of ecology, behavior and genetics. They have collaborated with other investigators to estimate phylogenetic relationships among the species of finches and their relatives on the continent and in the Caribbean, and to identify the molecular mechanisms involved in the development of beaks that vary so conspicuously among the species. The research has been published in four books, most recently “How and Why Species Multiply” (2008) and “40 years of Evolution” (2014), both published by Princeton University Press.
Peter Grant is the Class of 1877 Professor Emeritus in the Department of Ecology and Evolutionary Biology at Princeton University, having trained at Cambridge University and the University of British Columbia. Before joining Princeton in 1986 he taught at McGill University and the University of Michigan. Rosemary Grant is Research Scholar and Professor Emerita in the same Department. She received her training at Edinburgh University and Uppsala University, and taught at Princeton University.