Abstract
Inbreeding depression is widely hypothesized to drive adaptive evolution of precopulatory and post‐copulatory mechanisms of inbreeding avoidance, which in turn are hypothesized to affect evolution of polyandry (i.e. female multiple mating). However, surprisingly little theory or modelling critically examines selection for precopulatory or post‐copulatory inbreeding avoidance, or both strategies, given evolutionary constraints and direct costs, or examines how evolution of inbreeding avoidance strategies might feed back to affect evolution of polyandry. Selection for post‐copulatory inbreeding avoidance, but not for precopulatory inbreeding avoidance, requires polyandry, whereas interactions between precopulatory and post‐copulatory inbreeding avoidance might cause functional redundancy (i.e. ‘degeneracy’) potentially generating complex evolutionary dynamics among inbreeding strategies and polyandry. We used individual‐based modelling to quantify evolution of interacting precopulatory and post‐copulatory inbreeding avoidance and associated polyandry given strong inbreeding depression and different evolutionary constraints and direct costs. We found that evolution of post‐copulatory inbreeding avoidance increased selection for initially rare polyandry and that evolution of a costly inbreeding avoidance strategy became negligible over time given a lower‐cost alternative strategy. Further, fixed precopulatory inbreeding avoidance often completely precluded evolution of polyandry and hence post‐copulatory inbreeding avoidance, but fixed post‐copulatory inbreeding avoidance did not preclude evolution of precopulatory inbreeding avoidance. Evolution of inbreeding avoidance phenotypes and associated polyandry is therefore affected by evolutionary feedbacks and degeneracy. All else being equal, evolution of precopulatory inbreeding avoidance and resulting low polyandry is more likely when post‐copulatory inbreeding avoidance is precluded or costly, and evolution of post‐copulatory inbreeding avoidance greatly facilitates evolution of costly polyandry.
Highlights
Inbreeding, defined as reproduction between relatives, often greatly reduces the fitness of resulting inbred offspring
We model inbreeding depression as having an absolute rather than relative effect on offspring viability so that the effect of b is consistent across generations and different parameter combinations
When post-copulatory inbreeding avoidance alleles (Fa) had no effect (i.e. Fg values were fixed to zero), meaning that Fp could not evolve, Pa alleles underlying polyandry decreased to negative values over generations
Summary
Inbreeding, defined as reproduction between relatives, often greatly reduces the fitness of resulting inbred offspring (termed ‘inbreeding depression’; Charlesworth & Charlesworth, 1999; Keller & Waller, 2002; Charlesworth & Willis, 2009). To ensure that immigrants do not directly affect genotypic or phenotypic values of tendency for polyandry or precopulatory or post-copulatory inbreeding avoidance, immigrants are always male. When post-copulatory inbreeding avoidance alleles (Fa) had no effect (i.e. Fg values were fixed to zero), meaning that Fp could not evolve, Pa alleles underlying polyandry decreased to negative values over generations (red lines, Fig. 1a,c,e,g).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
