title: The effect of cryptic female choice on sex allocation in simultaneous hermaphrodites.
abstract: Sex allocation theory for simultaneous hermaphrodites has focused primarily on the effects of sperm competition, but the role of mate choice has so far been neglected. We present a model to study the coevolution of cryptic female choice and sex allocation in simultaneous hermaphrodites. We show that the mechanism of cryptic female choice has a strong effect on the evolutionary outcome: if individuals remove a fixed proportion of less-preferred sperm, the optimal sex allocation is more female biased (i.e. more biased towards egg production) than without cryptic female choice; conversely, if a fixed amount of sperm is removed, sex allocation is less female-biased than without cryptic female choice, and can easily become male biased (i.e. biased towards sperm production). Under male-biased sex allocation, hermaphroditism can become unstable and the population can split into pure males and hermaphrodites with a female-biased allocation. We discuss the idea that the evolution of sex allocation may depend on the outcome of sexual conflict over the fate of received sperm: the sperm donor may attempt to manipulate or by-pass cryptic female choice and the sperm recipient is expected to resist such manipulation. We conclude that cryptic female choice can have a strong influence on sex allocation in simultaneous hermaphrodites and strongly encourage empirical work on this question.
authors.affiliation: Theoretical Biology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9751 Haren, The Netherlands. e.van.velzen@rug.nl
authors.forename: Ellen
authors.initials: E
authors.lastname: van Velzen
authors.forename: Lukas
authors.initials: L
authors.lastname: Schärer
authors.forename: Ido
authors.initials: I
authors.lastname: Pen
mesh_terms: D000818:Animals; D005075:Biological Evolution; D012734:Disorders of Sex Development; D005260:Female; D008297:Male; D008954:Models, Biological; D010063:Ovum / Q000502:physiology; D019849:Sex Determination Processes; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology