The many consequences of polyandry for population dynamics

Background/Question/Methods

Polyandry, by elevating sexual conflict and selecting for reduced male care relative to monandry, may exacerbate the cost of sex and thereby seriously impact population fitness. On the other hand, polyandry has a number of possible population-level benefits over monandry, such as increased sexual selection leading to faster adaptation and a reduced mutation load. Here, I review some of the many ways in which fitness is affected by polyandry, and discuss how this might influence population dynamics.

Results/Conclusions

I conclude that it is far from clear whether polyandry has a net positive or negative effect on female fitness, or if its individual-level effects will have visible demographic consequences. In populations that produce many more offspring than can possibly survive and breed, offspring gained or lost as a result of polyandry may not affect population size. Such ecological “masking” of changes in population fitness could hide a response that only manifests under adverse environmental conditions (e.g. anthropogenic change). Empirical studies could seek to determine the net effect of polyandry on population dynamics, and future models could seek to clarify the link between individual and population fitness.