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How many founders, how large a population?
Kevin Willis1, Raymond E Willis
1Minnesota Zoo, Apple Valley, Minnesota 55124, USA. Kevin.Willis@State.MN.US
Zoo Biology
|February 4, 2010
Summary
Balancing population founders and size is key for retaining gene diversity. A cost-effectiveness model shows the optimal number of founders depends on the relative costs of increasing founders versus population size.
Area of Science:
- Population genetics
- Conservation biology
- Quantitative genetics
Background:
- Gene diversity retention is crucial for long-term population viability.
- Population size and the number of founders are key determinants of genetic diversity.
- Current recommendations for founder numbers may not be cost-optimal.
Purpose of the Study:
- To develop a model for determining the most cost-effective balance between the number of population founders and population size.
- To identify optimal strategies for retaining gene diversity over specified timeframes.
Main Methods:
- A model was developed comparing the marginal costs of increasing founder numbers versus population size.
- Marginal costs were defined as the cost per additional animal for founders or population size.
- The model evaluated cost-effectiveness for retaining 90% gene diversity over 10-15 generations.
Main Results:
- The current recommendation of 20 effective founders is near the least-cost solution when marginal costs are equal.
- The optimal number of founders significantly deviates from 20 when the ratio of marginal costs is not equal to one.
- Cost-effectiveness is sensitive to the relative economic inputs for founder acquisition versus population growth.
Conclusions:
- The optimal number of founders for gene diversity retention is contingent on the ratio of marginal costs.
- A flexible approach considering economic factors is necessary for effective conservation strategies.
- The 20-founder guideline may require adjustment based on specific cost-benefit analyses in conservation programs.
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