Sexually transmitted infection and the evolution of serial monogamy

Abstract

The selective forces shaping mating systems have long been of interest to biologists. One particular selective pressure that has received comparatively little attention is sexually transmitted infections (STIs). While it has been hypothesized that STIs could drive the evolutionary emergence of monogamy, there is little theoretical support. Here we use an evolutionary invasion analysis to determine what aspects of pathogen virulence and transmission are necessary for serial monogamy to evolve in a promiscuous population. We derive a biologically intuitive invasion condition in terms of population-specific quantities. From this condition, we obtain two main results. First, when pathogen virulence causes mortality rather than sterility, monogamy is more likely to evolve. Second, we find that at intermediate pathogen transmission rates, monogamy is the most selectively advantageous, whereas at high-and lowtransmission rates, monogamy is generally selected against. As a result, it is possible for a pathogen to be highly virulent, yet for promiscuity to persist.

Coevolution of parasite virulence and host mating strategies

“…Our work supports a growing body of theory that parasites play a key role in shaping the evolution of mating strategies (12,14,15,17,19,24), but empirical evidence for parasite-mediated sexual selection is mixed. Host behavior consistent with the transmissionavoidance hypothesis has been identified among birds (2-4), rodents (49,50), fish (51), fruit flies (52), and humans (53), yet no evidence has been found in studies of beetles (13,16) and nonhuman primates (54).…”

“…Although a large number of studies have explored the effects of sexual contact patterns on epidemiology or parasite evolution, or the consequences of parasite-mediated sexual selection for the evolution of mate choice (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), to our knowledge this is the first examination of both host mating behavior and parasite virulence in a coevolutionary context. Ecological feedbacks are crucial in shaping selection in both hosts and parasites (36)(37)(38)(39)(40)(41).…”

“…Hosts with intermediate life spans, however, have moderate levels of disease, so the ability to discriminate between infected and noninfected individuals is advantageous. This pattern is reminiscent of other biological phenomena that are predicted to peak at intermediate levels of disease, including investment in immune responses (44), sociality (45), sexual reproduction (41), and serial monogamy (19). Life span has previously been shown to be important in the evolution of defenses against parasitism, but existing theory has tended to focus on immune responses rather than behavioral defenses (46).…”

“…host-parasite coevolution | mate choice | virulence | transmission avoidance | sexually transmitted infection S ince Hamilton and Zuk (1) first proposed that parasitism may explain the existence of secondary sex traits such as the peacock's tail, there has been considerable interest in the role that parasites play in sexual selection and the evolution of mating strategies (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). A prominent theory, known as the transmissionavoidance hypothesis, posits that secondary sex traits, and more generally, mating strategies, have evolved to limit the risk of contracting an infection (10).…”

Monogamy: Cause, Consequence, or Corollary of Success in Wild Canids?

“…Such males benefit doubly, genetically and from the parental investment of cuckolded males, thus extraterritorial forays are widely recorded amongst canids during the courtship and mating periods (e.g., Macdonald, 1981;Zoellick and Smith, 1992;Deuel et al, 2017;Kamler et al, 2017Kamler et al, , 2019. However, the costs of male philandering include leaving their mate unguarded and therefore increasing their own risk of being cuckolded, increased exposure to sexually transmitted disease and parasites (Poiani and Wilks, 2000;McLeod and Day, 2014), and risks of mortality, predation, intraspecific conflict and stress when traveling in unfamiliar areas (Harris and Smith, 1987;Young and Monfort, 2009).…”