Bompard Anaïs, Amat Isabelle, Fauvergue Xavier, Spataro Thierry
Institute of Ecology and Environmental Sciences of Paris, UMR 7618, UPMC-CNRS, Paris, 75005, France.
Department of Infectious Diseases Epidemiology, University of London Imperial College of Science, Technology & Medicine, Norfolk Place, W21PG London, UK.
Ecology. 2016 Nov;97(11):3131-3142. doi: 10.1002/ecy.1544.
Extinctions have no simple determinism, but rather result from complex interplays between environmental factors and demographic-genetic feedback that occur at small population size. Inbreeding depression has been assumed to be a major trigger of extinction vortices, yet very few models have studied its consequences in dynamic populations with realistic population structure. Here we investigate the impact of Complementary Sex Determination (CSD) on extinction in parasitoid wasps and other insects of the order Hymenoptera. CSD is believed to induce enough inbreeding depression to doom simple small populations to extinction, but we suggest that in parasitoids CSD may have the opposite effect. Using a theoretical model combining the genetics of CSD and the population dynamics of host-parasitoid systems, we show that CSD can reduce the risk of parasitoid extinction by reducing fluctuations in population size. Our result suggests that inbreeding depression is not always a threat to population survival, and that considering trophic interactions may reverse some pervasive hypotheses on its demographic impact.
物种灭绝并非由单一因素决定，而是环境因素与在小种群规模下发生的种群统计学 - 遗传反馈之间复杂相互作用的结果。近亲繁殖衰退被认为是灭绝漩涡的主要触发因素，但很少有模型研究其在具有现实种群结构的动态种群中的后果。在此，我们研究互补性性别决定（CSD）对寄生蜂及膜翅目其他昆虫灭绝的影响。据信CSD会引发足够的近亲繁殖衰退，致使简单的小种群走向灭绝，但我们认为在寄生蜂中CSD可能会产生相反的效果。通过一个结合CSD遗传学和寄主 - 寄生蜂系统种群动态的理论模型，我们表明CSD可通过减少种群规模波动来降低寄生蜂灭绝的风险。我们的结果表明，近亲繁殖衰退并不总是对种群生存构成威胁，并且考虑营养相互作用可能会颠覆一些关于其种群统计学影响的普遍假设。
