Data from: Evolution of pre-copulatory and post-copulatory strategies of inbreeding avoidance and associated polyandry

Inbreeding depression is widely hypothesised to drive adaptive evolution of pre-copulatory and post-copulatory mechanisms of inbreeding avoidance, which in turn are hypothesised to affect evolution of polyandry (i.e., female multiple mating). However, surprisingly little theory or modelling critically examines selection for pre-copulatory 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 pre-copulatory inbreeding avoidance, requires polyandry, while interactions between pre-copulatory 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 pre-copulatory 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 pre-copulatory 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 pre-copulatory inbreeding avoidance. Evolution of inbreeding avoidance phenotypes and associated polyandry are therefore affected by evolutionary feedbacks and degeneracy. All else being equal, evolution of pre-copulatory 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.

近交衰退（inbreeding depression）被广泛假说为驱动交配前（pre-copulatory）与交配后（post-copulatory）近交回避机制适应性演化的核心动力，而这些近交回避机制反过来又被假说会影响多配（polyandry，即雌性多次交配）的演化。然而，令人惊讶的是，现有研究中极少有理论或模型会在考虑演化约束与直接成本的前提下，严格检验针对交配前、交配后近交回避或两者兼具的选择压力，也未探讨近交回避策略的演化如何通过反馈作用影响多配的演化。仅交配后近交回避的选择压力需要多配作为前提，而交配前与交配后近交回避之间的相互作用可能引发功能冗余（即“简并性（degeneracy）”），进而可能在近交策略与多配之间催生复杂的演化动力学。本研究采用基于个体的建模（individual-based modelling）方法，量化了在强近交衰退以及不同演化约束与直接成本条件下，相互作用的交配前、交配后近交回避与相关多配的演化过程。研究结果显示，交配后近交回避的演化会增强对原本罕见的多配的选择压力；而当存在低成本替代策略时，高成本近交回避策略的演化会随时间推移变得可忽略不计。此外，固定的交配前近交回避通常会完全阻断多配乃至交配后近交回避的演化，但固定的交配后近交回避并不会阻碍交配前近交回避的演化。因此，近交回避表型与相关多配的演化受到演化反馈与简并性的共同影响。在其他条件均相同的情况下，当交配后近交回避被排除或成本高昂时，交配前近交回避的演化及其导致的低多配水平会更易发生；而交配后近交回避的演化则会极大地促进高成本多配的演化。