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

摘要: 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 limited vacancies and dispersal opportunities. We tested several hypotheses divorce in such a species, the cooperatively breeding bird Malurus coronatus. Based 9 years of detailed information survival 317 pairs, we whether driven by inbreeding avoidance, better or territory, social variables (number subordinates fidelity partners). found escape incest: incestuous pairs were substantially more likely (64%) than non-incestuous (14%). However, pair bonds lasted up year, highlighting breeder dispersal. Non-incestuous also divorced, but here only predictor was presence extrapair offspring previous brood. Although reproductive failure did not trigger divorce, success year following females dispersed after obtained higher quality territories, unlike their died. Thus, may long-term benefits associated territories. Some divorces appeared forced evictions older females, although direct evidence this limited. Taken together, our findings demonstrate complexity factors affect occurrence when constrained.