Sexually transmitted infections in polygamous mating systems

Abstract

Sexually transmitted infections (STIs) are often associated with chronic diseases and can have severe impacts on host reproductive success. For airborne or socially transmitted pathogens, patterns of contact by which the infection spreads tend to be dispersed and each contact may be of very short duration. By contrast, the transmission pathways for STIs are usually characterized by repeated contacts with a small subset of the population. Here we review how heterogeneity in sexual contact patterns can influence epidemiological dynamics, and present a simple model of polygyny/polyandry to illustrate the impact of biased mating systems on disease incidence and pathogen virulence.

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).…”

“…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).…”

“…Hence, sexually transmitted infections, which are common in both plants (21) and animals (22), are likely to be a key factor in the evolution of mating strategies. Furthermore, sexually transmitted infections typically exhibit different epidemiological dynamics (17,23) and disease outcomes (e.g., sterility rather than mortality; ref. 22) to other infectious diseases.…”

The polyandry revolution

“…The review illustrates how one possible evolutionary response to combat the spread of SGEs is polyandry through which females can penalize the reproductive success of carrier males. Ashby & Gupta [31] focus on sexually transmitted infections (STIs). The authors present a new theoretical framework to study the way varying levels of polyandry can change the epidemiological dynamics of these infections.…”