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Title: Possible human impacts on adaptive radiation: beak size bimodality in Darwin's finches
Contributor(s): Hendry, AP (author); Grant, PR (author); Grant, R (author); Ford, HA  (author); Brewer, MJ (author); Podos, J (author)
Publication Date: 2006
DOI: 10.1098/rspb.2006.3534
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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, has lost this property in concert with a marked increase in local human population density. We next show that a nearby site with lower human impacts, El Garrapatero, currently manifests strong bimodality. This comparison suggests that bimodality can persist when human densities are low (Academy Bay in the past, El Garrapatero in the present), but not when they are high (Academy Bay in the present). Human activities may negatively impact diversification in 'young' adaptive radiations, perhaps by altering adaptive landscapes.
Publication Type: Journal Article
Source of Publication: Proceedings of the Royal Society B: Biological Sciences, 273(1596), p. 1887-1894
Publisher: The Royal Society
Place of Publication: United Kingdom
ISSN: 0962-8452
Field of Research (FOR): 060305 Evolution of Developmental Systems
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
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