Sexually transmitted infections are ubiquitous in nature and affect many populations. The key process for their transmission is mating, usually preceded by mate choice. Susceptible individuals may avoid mating with infected individuals to prevent infection provided it is recognizable. We show that accounting for infection avoidance significantly alters host population dynamics. We observe bistability between the disease-free and endemic or disease-induced extinction equilibria, significant abrupt reduction in the host population size and disease-induced host extinction. From the population persistence perspective, the best strategy is either not to avoid mating with the infected individuals, to prevent disease-induced host extinction, or to completely avoid mating with the infected individuals, to prevent pathogen invasion. Increasing sterilization efficiency of the infection leads to lower population sizes and reduced effect of mating avoidance. We also find that the disease-free state is more often attained by populations with strong polyandry, whereas a high-density endemic state is more often observed for populations with strong polygyny, suggesting that polygamy rather than monogamy may be promoted in denser host populations.

Czech Academy of Sciences Biology Centre Institute of Entomology Department of Ecology Branišovská 31 České Budějovice 37005 Czech Republic; Centre for Mathematical Biology Institute of Mathematics Faculty of Science University of South Bohemia Branišovská 1760 České Budějovice 37005 Czech Republic

Department of Mathematics and Statistics Faculty of Science Masaryk University Kotlářská 2 Brno 61137 Czech Republic

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