How does female mate choice influence male reproductive tactics and postcopulatory competition in midshipman?

plainfin-top “Postcopulatory consequences of female mate choice in a fish with alternative reproductive tactics”. 2016. Behavioral Ecology 27 (1), 312-320

John L. Fitzpatrick (Stockholm University) and authors describe how female mate choice can potentially influence sperm competition risk and shape investment patterns in males between and within male reproductive tactics.

In this paper the authors explore alternative male mating behaviors and female mate choice influences male investment in reproductive traits that enhance sperm competition, a form of postcopulatory male–male competition.

The plainfin midshipman (Porichthys notatus) is a marine fish species which can be found in the intertidal,  and has 2 alternative reproductive tactics – guarder and sneaker males. Female mate choice is associated with variation in sperm competition risk between the guarder and sneaker males, as well as among males using the same reproductive tactic. Larger guarder males, which attract more females and experience higher rates of cuckoldry, appear adapted to this increased sperm competition risk by producing faster sperm than smaller guarder males. The smallest sneaker males had faster swimming sperm than guarder males, suggesting that female choice can amplify the selection gradient acting on males both between and within reproductive tactics.

photos: courtesy J.L. Fitzpatrick