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Possible Mechanism For First Sperm Precedence In The Hermaphroditic Freshwater Snail Planorbella Trivolvis, Cynthia Norton

Biology Faculty Scholarship

In hermaphrodites the impact of mating order on fertilization success may not only shape the evolution of sperm competition but also influence gender roles during copulation. Planorbella trivolvis exhibit strong first sperm precedence – when snails are presented with two mates 24 hours apart, most eggs (over 80%) are fertilized by the first mate. This outcome may be explained if sperm from the first mate fill the storage organ so there is no room for additional sperm. It may also indicate a switch in gender role so that the focal animal acts as male, and not in the female role …