Behavioural Ecology and Ecophysiology Group, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium
Behavioural Ecology and Ecophysiology Group, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium.
Proc Biol Sci. 2018 May 30;285(1879). doi: 10.1098/rspb.2018.0231.
Inbreeding depression plays a significant role in evolutionary biology and ecology. However, we lack a clear understanding of the fitness consequences of inbreeding depression. Studies often focus on short-term effects of inbreeding in juvenile offspring, whereas inbreeding depression in adult traits and the interplay between inbreeding depression and age are rarely addressed. Inbreeding depression may increase with age and accelerate the decline in reproductive output in ageing individuals (reproductive senescence), which could be subject to sex-specific dynamics. We test this hypothesis with a longitudinal experimental study in a short-lived songbird. Adult inbred and outbred male and female canaries were paired in a 2 × 2 factorial design, and survival and annual reproductive performance were studied for 3 years. We found inbreeding depression in female egg-laying ability, male fertilization success and survival of both sexes. Annual reproductive success of both males and females declined when paired with an inbred partner independent of their own inbreeding status. This shows that inbreeding can have fitness costs in outbred individuals when they mate with an inbred individual. Further, inbred females showed faster reproductive senescence than outbred females, confirming that inbreeding depression and age can interact to affect fitness. By contrast, there was no evidence for an interaction between inbreeding depression and reproductive senescence in male fertilization success. Our findings highlight the importance of considering sex-specific effects and age to determine the full range of fitness consequences of inbreeding and demonstrate that inbreeding depression can accelerate reproductive senescence.
近亲繁殖衰退在进化生物学和生态学中起着重要作用。然而，我们对近亲繁殖衰退对适应度的影响仍缺乏清晰的认识。研究通常集中在近亲繁殖对幼年后代的短期影响上，而对成年特征的近亲繁殖衰退以及近亲繁殖衰退与年龄之间的相互作用则很少涉及。近亲繁殖衰退可能会随着年龄的增长而增加，并加速老年个体生殖产出的下降（生殖衰老），这可能受到性别特异性动态的影响。我们通过对一种短寿命鸣禽进行的纵向实验研究来检验这一假设。在一个 2×2 的析因设计中，将成年近亲繁殖和远交繁殖的雄性和雌性金丝雀配对，并对它们的 3 年生存和年度生殖表现进行了研究。我们发现雌性产卵能力、雄性受精成功率和两性的存活率都存在近亲繁殖衰退。当雌雄两性与近亲繁殖的个体配对时，它们的年度生殖成功率都会下降，而与它们自身的近亲繁殖状态无关。这表明，当远交个体与近亲个体交配时，近亲繁殖可能会对它们的适应度造成代价。此外，近亲繁殖的雌性比远交繁殖的雌性表现出更快的生殖衰老，这证实了近亲繁殖衰退和年龄可以相互作用影响适应度。相比之下，在雄性受精成功率方面，没有证据表明近亲繁殖衰退和生殖衰老之间存在相互作用。我们的研究结果强调了考虑性别特异性效应和年龄的重要性，以确定近亲繁殖对适应度的全部影响，并证明了近亲繁殖衰退可以加速生殖衰老。
