Polygamy and purifying selection in birds

Area of Science:

• Evolutionary Biology
• Genetics
• Animal Behavior

Background:

• Sexual selection theories propose differing impacts of mating systems on genetic quality.
• Good genes theories predict polygamy enhances purifying selection, while runaway selection theories do not.

Purpose of the Study:

• To investigate the relationship between mating systems (monogamy vs. polygamy) and the efficiency of purifying selection in birds.
• To test whether observed patterns align with "good genes" or runaway selection hypotheses.

Main Methods:

• Analysis of polymorphism data from 150 bird genome assemblies.
• Comparison of nonsynonymous to synonymous polymorphism ratios between monogamous and polygamous species.
• Statistical analysis controlling for effective population size.

Main Results:

• Polygamous species showed significantly fewer nonsynonymous polymorphisms relative to synonymous polymorphisms compared to monogamous species.
• This effect was independent of effective population size, supporting "good genes" theories.
• Polygamy did not significantly impact overall genetic diversity, but female polygamy (polyandry) showed a marginal effect.

Conclusions:

• Polygamy is associated with more efficient purifying selection in birds, consistent with "good genes" sexual selection.
• The findings support the alignment of sexual and natural selection in polygamous systems.
• Mating systems play a role in shaping genome-wide genetic variation and selection efficiency.