The Wages of Inbreeding

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Science  25 Aug 2000:
Vol. 289, Issue 5483, pp. 1257
DOI: 10.1126/science.289.5483.1257c

That inbreeding reduces fitness (measured as reproductive output) is a well-established principle in population genetics. Inbreeding depression arises from increased homozygosity at loci influencing fitness and has practical consequences for the conservation of small populations or rare species. Nevertheless, it has been difficult to document unequivocally the effects of inbreeding in wild populations of animals, because measures of fitness require many years of observation and because pedigrees of individual animals are hard to ascertain.

Slate et al. have now provided such a demonstration, using many years of observations of a wild population of red deer (Cervus elaphus) on the Isle of Rum, Scotland. The lifetime breeding success (LBS) of females was measured as the number of calves born; LBS of males was assessed from behavioral observations during the breeding season. Inbreeding depression was estimated from heterozygosity of microsatellite markers. Clear correlations between LBS and heterozygosity were found for both males and females, the first time that inbreeding depression (or its converse, heterosis or ‘hybrid vigor’) has been shown for a wild animal population. — AMS

Proc. R. Soc. Lond. B. 267, 1657 (2000).

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