6533b82dfe1ef96bd1291c10

RESEARCH PRODUCT

Multiple mating by females is a natural outcome of a null model of mate encounters

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Why do females of so many species mate multiply? The question makes use of an implicit null model that females by default should be monandrous and that polyandry requires an explanation. Here, we make thesimplepoint that females encountermates overtheir lifetimeina stochasticmanner,andas theyshouldacceptatleastonemale,acceptanceofallmales maybea betternullmodelthanthemore advanced strategy of accepting thefirst satisfactory one and rejecting all others. The advantage of this view is that it makes it explicit that females must accept and reject mates without precise knowledge of future mate encounters. In insects, for example, limitations of cognitive and sensory capabilities make it hard for females to compare many potential mates simultaneously. It is then not always possible for a female to be very choosy (i.e., to reject a large proportion of encounters) without simultaneously increasing the expected time spent as a virgin and decreasing the overall expected number of mates she accrues during her lifetime. We show that this fact easily leads to a pattern where choosiness isreduced and most females mate withmoremales thantheir optimalmate number.Our results suggest that monandry and polyandry may be less distinct strategies than they first appear as they may,toalargeextent,reflectchanceeventsinfluencingmateencounters.Polyandrycanariseasaside effectofavoidingtheriskofencounteringtoofewacceptablemates–a viewpoint that is easilymissed if females that haveremainedunmated arenotincludedindatasets.