Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches.

ABSTRACT: Adaptive radiation is facilitated by a rugged adaptive landscape, where fitness peaks correspond to trait values that enhance the use of distinct resources. Different species are thought to occupy the different peaks, with hybrids falling into low-fitness valleys between them. We hypothesize that human activities can smooth adaptive landscapes, increase hybrid fitness and hamper evolutionary diversification. We investigated this possibility by analysing beak size data for 1755 Geospiza fortis measured between 1964 and 2005 on the island of Santa Cruz, Galápagos. Some populations of this species can display a resource-based bimodality in beak size, which mirrors the greater beak size differences among species. We first show that an historically bimodal population at one site, Academy Bay, h

SUBMITTER: Hendry AP 

PROVIDER: S-EPMC1797601 | biostudies-literature | 2006 Aug

REPOSITORIES: biostudies-literature