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Published on: May 1, 2021
Genetic adaptation to captivity can occur in a single generation
Mark R Christie1, Melanie L Marine, Rod A French
1Department of Zoology, Oregon State University, Corvallis, OR 97331-2914, USA. christim@science.oregonstate.edu
Summary
Captive breeding programs can reduce the wild fitness of endangered species. A single generation in captivity can lead to domestication selection, where traits beneficial in captivity become maladaptive in the wild.
Area of Science:
- Conservation Biology
- Evolutionary Biology
- Fisheries Science
Background:
- Captive breeding is crucial for conserving threatened species, but reintroduction often fails due to reduced fitness in wild environments.
- The exact causes of this fitness decline remain unclear, with hypotheses including environmental factors, inbreeding, relaxed selection, and domestication.
Purpose of the Study:
- To investigate the role of domestication selection in the decline of steelhead (Oncorhynchus mykiss) fitness in the Hood River, Oregon.
- To analyze multigenerational pedigree data to understand the impact of captive breeding on wild population success.
Main Methods:
- Utilized a multigenerational pedigree analysis of steelhead in the Hood River, Oregon.
- Compared reproductive success of wild-born and first-generation hatchery fish under captive and wild conditions.
- Assessed the correlation between captive-environment fitness and wild-environment offspring success.
Main Results:
- First-generation hatchery steelhead exhibited double the reproductive success in captivity compared to wild fish under identical conditions, indicating rapid adaptation to captivity.
- A significant trade-off was observed: steelhead broodstock with higher captive fitness produced offspring with lower success in the wild.
- Steelhead offspring from successful captive broodstock (≥5 returning siblings) had substantially lower wild reproductive success (0.62 offspring) than those from less successful broodstock (<5 siblings, 2.05 offspring).
Conclusions:
- Domestication selection, driven by adaptation to the captive environment, is a primary cause of reduced fitness in reintroduced hatchery steelhead.
- Even a single generation of captive breeding can rapidly select for traits that are detrimental to survival and reproduction in the wild.
- Conservation breeding programs must carefully manage selection pressures to avoid maladaptive evolutionary changes and ensure successful species restoration.
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