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Causes and consequences of pair‐bond disruption in a sex‐skewed population of a long‐lived monogamous seabird
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Edité par CCSD ; Ecological Society of America -
International audience. Many animals form long‐term monogamous pair‐bonds, and the disruption of a pair‐bond (through either divorce or widowhood) can have significant consequences for individual vital rates (survival, breeding, and breeding success probabilities) and life‐history outcomes (lifetime reproductive success, life expectancy). Here, we investigated the causes and consequences of pair‐bond disruption in wandering albatross (Diomedea exulans). State‐of‐the‐art statistical and mathematical approaches were developed to estimate divorce and widowhood rates and their impacts on vital rates and life‐history outcomes. In this population, females incur a higher mortality rate due to incidental fishery bycatch, hence the population is male‐skewed. Therefore, we first posited that males show higher widowhood rates negatively correlated with fishing effort, and females have higher divorce rates because they have more mating opportunities. Furthermore, we expected that divorce can be an adaptive strategy, whereby individuals improve breeding success by breeding with a new partner of better quality. Finally, we posited that pair‐bond disruptions can reduce survival and breeding probabilities due to the cost of remating processes, with important consequences for life‐history outcomes. As expected, we show that males have higher widowhood rates than females and females have higher divorce rates in this male‐skewed population. However, no correlation was found between fishing effort and male widowhood. Secondly, contrary to our expectation, we found that divorce is likely non‐adaptive in this population. We propose that divorce in this population is caused by an intruder who outcompetes the original partner in line with the “forced divorce” hypothesis. Furthermore, we found a 16.7% and 18.0% reduction in lifetime reproductive success (LRS) only for divorced and widowed males, respectively, due to missing breeding seasons after a pair‐bond disruption. Finally, we found that divorced individuals are more likely to divorce again, but whether this is related to specific individual characteristics remains an important area of investigation.
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