In Vitro Fertilization Experiments Using Sockeye Salmon Reveal That Bigger Eggs Are More Fertilizable Under Sperm Limitation

Theory and evidence show that egg size evolves to optimise offspring and maternal fitness. However, an additional theory invokes sperm limitation as an important force, if increasing egg size acts as a bigger target for fertilization when gamete encounter rate is diluted. We test this theory using in vitro fertilization experiments in externally-fertilizing sockeye salmon, where there is considerable variation in ovum size.

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Filed under: Fertility on April 15th, 2009