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Genetic purging in captive endangered ungulates with extremely low effective population sizes
Eugenio López-Cortegano1, Eulalia Moreno2, Aurora García-Dorado3
1Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, Edinburgh, UK. e.lopez-cortegano@ed.ac.uk.
Heredity
|September 29, 2021
Summary
Genetic purging can reduce inbreeding depression in endangered ungulates, especially in smaller populations like Gazella cuvieri and Nanger dama. Management strategies should balance population size with natural selection to enhance long-term survival.
Area of Science:
- Conservation Biology
- Population Genetics
- Animal Breeding
Background:
- Inbreeding depression threatens small populations, but genetic purging can mitigate its effects by exposing and removing deleterious recessive alleles.
- Captive breeding programs for endangered species often prioritize population growth, potentially impacting genetic health.
Purpose of the Study:
- To investigate the occurrence and effectiveness of genetic purging in reducing inbreeding depression in four endangered ungulate captive breeding programs.
- To analyze the influence of population size and breeding strategies on genetic purging dynamics.
Main Methods:
- Analysis of early survival rates in pedigreed captive breeding programs of endangered ungulates.
- Application of inbreeding-purging theory to assess genetic load and inbreeding depression.
- Comparison of purging efficacy across species with varying effective population sizes (Ne).
Main Results:
- Substantial evidence of genetic purging was found in Gazella cuvieri (Ne=14) and Nanger dama (Ne=11), significantly reducing inbreeding depression.
- No purging was detected in Ammotragus lervia (Ne=4), consistent with drift overwhelming purging in rapidly inbreeding populations.
- In G. dorcas (Ne=39), purging was slower and not detected, likely due to its larger population size requiring more generations for detection.
Conclusions:
- Genetic purging can effectively reduce inbreeding load and depression in endangered ungulates when breeding contributions are influenced by natural selection.
- Management strategies maximizing effective population size may reduce purging; a compromise balancing these factors is recommended for long-term conservation.
- Allowing some random mating, natural selection in breeding, or early reintroduction can support purging and enhance species survival.
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