Northwest Fisheries Science Center

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Document Type: Chapter or Section
Center: NWFSC
Document ID: 902
Type of Book: Technical
Section or Chapter Title: Human-induced evolution caused by unnatural selection through harvest of wild animals
Book Title: In the light of evolution, vol. III: two centuries of Darwin
Author: Fred W. Allendorf, Jeffrey J. Hard
Editor: John C. Avise, Francisco J. Ayala (Eds.)
Publication Year: 2009
Publisher: The National Academies Press. Washington, D.C
Volume: 106
Pages: 129-148
Keywords: Conservation, genetic change, human exploitation

Human harvest of phenotypically desirable animals from wild populations imposes selection that can reduce the frequencies of those desirable phenotypes. Hunting and fishing contrast with agricultural and aquacultural practices in which the most desirable animals are typically bred with the specific goal of increasing the frequency of desirable phenotypes. We consider the potential effects of harvest on the genetics and sustainability of wild populations. We also consider how harvesting could affect the mating system and thereby modify sexual selection in a way that might affect recruitment. Determining whether phenotypic changes in harvested populations are due to evolution, rather than phenotypic plasticity or environmental variation, has been problematic. Nevertheless, it is likely that some undesirable changes observed over time in exploited populations (e.g., reduced body size, earlier sexual maturity, reduced antler size, etc.) are due to selection against desirable phenotypesa process we call "unnatural" selection. Evolution brought about by human harvest might greatly increase the time required for over-harvested populations to recover once harvest is curtailed because harvesting often creates strong selection differentials, whereas curtailing harvest will often result in less intense selection in the opposing direction. We strongly encourage those responsible for managing harvested wild populations to take into account possible selective effects of harvest management and to implement monitoring programs to detect exploitation- induced selection before it seriously impacts viability.

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Notes: Book at National Academies Press