The search for mates is often accompanied with conspicuous behaviour or morphology that can be exploited by predators. Here we explore the evolutionary consequences of a trade-off that arises naturally between mate acquisition and risk of predation and study evolution of the rate at which male prey search for mates in a population subject to a mate-finding Allee effect and exposed to either generalist or specialist predators. Since we show that the mate search rate determines the strength of the mate-finding Allee effect, we can alternatively view this as evolution of the mate-finding Allee effect in prey. We contrast two different life histories and find that, predominantly, male prey either evolve towards the maximal mate search rate yielding the weakest possible mate-finding Allee effect (thus showing no adaptive response in mating behaviour to predation risk) or evolutionary bi-stability occurs. In the latter case, males evolve a relatively low mate search rate (hence a relatively strong mate-finding Allee effect, interpreted as an adaptive response of male prey to predation) when initially slow or the maximal mate search rate when initially fast. Disruptive selection does not occur in populations exposed to generalist predators but is possible when predators are specialists. The dimorphic phase, in which fast and conspicuous male prey coexist with slow and cryptic ones, is however but a transient in evolutionary dynamics as one branch goes extinct while the other evolves towards the maximal mate search rate.

Czech Academy of Sciences Biology Centre Institute of Entomology Department of Ecology Branišovská 31 České Budějovice 37005 Czech Republic; Institute of Mathematics and Biomathematics Faculty of Science University of South Bohemia Branišovská 1760 České Budějovice 37005 Czech Republic http www entu cas cz berec

Department of Infectious Diseases St Jude Children's Research Hospital 262 Danny Thomas Place Memphis TN 38105 USA; Viral Populations and Parthenogenesis Unit Department of Virology Pasteur Institute 25 28 Rue du Dr Roux Paris 75015 France

Faculty of Mathematics Natural Sciences and Information Technologies University of Primorska Glagoljaška 8 Koper SI 6000 Slovenia

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