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Rapid Loss of Genetic Variation in Large Captive Populations of Drosophila Flies: Implications for the Genetic Management of Captive Populations
Author(s) -
Briscoe D.A.,
Malpica J.M.,
Robertson A.,
Smith Gabrielle J.,
Frankham R.,
Banks R.G.,
Barker J.S.F.
Publication year - 1992
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1046/j.1523-1739.1992.06030416.x
Subject(s) - biology , captivity , captive breeding , zoology , population , genetic variation , effective population size , genetic variability , genetic monitoring , endangered species , ecology , demography , allele , genetics , microsatellite , sociology , habitat , gene , genotype
Levels of variation in eight large captive populations of D. melanogaster (census sizes ∼ 5000) that had been in captivity for periods from 6 months to 23 years (8 to 365 generations) were estimated from allozyme heterozygosities, lethal frequencies, and inversion heterozygosities and phenotypic variances, additive genetic variances ( V A ), and heritabilities ( h 2 ) for sternopleural bristle numbers. Correlations between all measures of variation except lethal frequencies were high and significant. All measures of genetic variation declined with time in captivity, with those for average heterozygosities, V A , and h 2 being significant. The effective population size ( N e ) was estimated to be 185–253 in these populations, only 0.037–0.051 of census size (N). Levels of allozyme heterozygosities declined rapidly in two large captive populations founded from another wild stock, being reduced by 86% and 62% within 2.5 years in spite of being maintained at sizes of approximately 1000 and 3500. Estimates of N e / N for these populations were only 0.016 and 0.004. Two estimates of N e / N for captive populations of D. pseudoobscura from data in the literature were also low at 0.036 and 0.012. Consequently, the rate of loss of genetic variation in captive populations and endangered species may be more rapid than hitherto recognized. Merely maintaining captive populations at large census sizes may not be sufficient to maintain essential genetic variation.