Incest avoidance, extrapair paternity, and territory quality drive divorce in a year-round territorial bird.

Divorce can be an important behavioral strategy to improve fitness. This is particularly relevant for species that are territorial year-round with continuous partnerships, where individuals face constraints on partner choice due to limited vacancies and dispersal opportunities. We tested several hypotheses for divorce in such a species, the cooperatively breeding bird Malurus coronatus. Based on 9 years of detailed information on dispersal and survival of 317 breeding pairs, we tested whether divorce is driven by inbreeding avoidance, by a better partner or territory, or by social variables (number of subordinates and fidelity of partners). We found that divorce is important to escape incest: incestuous pairs were substantially more likely to divorce (64%) than non-incestuous pairs (14%). However, incestuous pair bonds lasted up to a year, highlighting constraints on breeder dispersal. Non-incestuous pairs also divorced, but here the only predictor for divorce was the presence of extrap...

配偶离异可作为提升进化适合度的重要行为策略。这一点对于全年占据领地且维持长期配偶关系的物种尤为关键——这类物种因领地空位有限、扩散机会稀缺而面临配偶选择受限的困境。我们针对这类物种——合作繁殖鸟类华丽细尾鹩莺（Malurus coronatus），检验了多项关于配偶离异的假说。基于9年间针对317个繁殖对的扩散与存活情况的详细监测数据，我们验证了配偶离异是否由以下因素驱动：近交规避、寻求更优质配偶或领地，亦或是社会因素（从属个体数量与配偶忠贞度）。研究结果表明，配偶离异是规避近交的重要手段：近交繁殖对的离异率（64%）显著高于非近交繁殖对（14%）。但近交配偶关系最长可维持一年，这凸显了繁殖个体扩散所面临的限制。非近交繁殖对同样会发生配偶离异，但此情境下离异的唯一预测因子为存在婚外……