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🏊 Sperm Competition

When females mate with multiple males, sperm from different males compete to fertilize eggs. Evolution favors traits that improve competitive ability: more sperm, faster sperm, displacement, or incapacitation.

Probability of multiple mating
Generation: 0
Mean Sperm Count: 0.50
Mean Sperm Speed: 0.50
Paternity Variance: 0.00
Multiple Paternity: 0%
Parker's Theory: Males trade off ejaculate size vs mating frequency. High sperm competition → larger ejaculates, bigger testes. Last male precedence creates selection for displacement mechanisms.