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Updated: Mar 1, 2026
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Published on: August 18, 2023
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THE EVOLUTION OF FITNESS
1Department of Biology, University of California, Santa Cruz, California, 95064.
Summary
Natural selection increases population fitness each generation, while mutations and environmental changes decrease it. This study quantifies these fitness changes, suggesting an upper limit on the genetic benefits of mate choice.
Area of Science:
- Evolutionary biology
- Population genetics
Background:
- Population fitness is shaped by opposing evolutionary forces: natural selection increases it, while mutation and environmental changes decrease it.
- Quantifying these forces is crucial for understanding evolutionary dynamics.
Purpose of the Study:
- To measure the rate of change in mean population fitness per generation.
- To estimate the upper limit of the genetic advantage conferred by mate choice.
Main Methods:
- Direct comparison of fitness between selected and unselected populations.
- Indirect measurement of fitness using additive variance and the fundamental theorem of natural selection.
Main Results:
- Natural selection increases mean population fitness by 0.1%–30% per generation.
- Tentative estimates suggest this increase is typically between 1% and 10% per generation.
- These figures imply a 5%–10% upper limit on the genetic advantage of mate choice.
Conclusions:
- The rate of fitness increase due to natural selection is substantial but variable.
- Mate choice likely offers a limited genetic advantage, constrained by the overall rate of fitness change in populations.
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