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Limits to the Adaptive Potential of Small Populations

Limits to the Adaptive Potential of Small Populations Abstract Small populations are predicted to have reduced capacity to adapt to environmental change for two reasons. First, population genetic models indicate that genetic variation and potential response to selection should be positively correlated with population size. The empirical support for this prediction is mixed: DNA markers usually reveal low heterozygosity in small populations, whereas quantitative traits show reduced heritability only in the smallest and most inbred populations. Quantitative variation can even increase in bottlenecked populations although this effect seems unlikely to increase the adaptive potential of populations. Second, individuals in small populations have lower fitness owing to environmental stress and genetic problems such as inbreeding, which can substantially increase the extinction probability of populations in changing environments. This second reason has not been included in assessments of critical population size assuring evolvability and makes it likely that many small threatened populations have a decreased potential for adaptation. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Annual Review of Ecology, Evolution, and Systematics Annual Reviews

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References (134)

Publisher
Annual Reviews
Copyright
Copyright © 2006 by Annual Reviews. All rights reserved
ISSN
0066-4162
DOI
10.1146/annurev.ecolsys.37.091305.110145
Publisher site
See Article on Publisher Site

Abstract

Abstract Small populations are predicted to have reduced capacity to adapt to environmental change for two reasons. First, population genetic models indicate that genetic variation and potential response to selection should be positively correlated with population size. The empirical support for this prediction is mixed: DNA markers usually reveal low heterozygosity in small populations, whereas quantitative traits show reduced heritability only in the smallest and most inbred populations. Quantitative variation can even increase in bottlenecked populations although this effect seems unlikely to increase the adaptive potential of populations. Second, individuals in small populations have lower fitness owing to environmental stress and genetic problems such as inbreeding, which can substantially increase the extinction probability of populations in changing environments. This second reason has not been included in assessments of critical population size assuring evolvability and makes it likely that many small threatened populations have a decreased potential for adaptation.

Journal

Annual Review of Ecology, Evolution, and SystematicsAnnual Reviews

Published: Dec 1, 2006

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