Data from: Increased fluctuation in a butterfly metapopulation leads to diploid males and decline of a hyperparasitoid

Climate change can increase spatial synchrony of population dynamics, leading to large-scale fluctuation that destabilizes communities. High trophic level species such as parasitoids are disproportionally affected because they depend on unstable resources. Most parasitoid wasps have complementary sex determination, producing sterile males when inbred, which can theoretically lead to population extinction via the diploid male vortex. We examined this process empirically using a hyperparasitoid population inhabiting a spatially structured host population in a large fragmented landscape. Over four years of high host butterfly metapopulation fluctuation, diploid male production by the wasp increased, and effective population size declined precipitously. Our multitrophic spatially structured model shows that host population fluctuation can cause local extinctions of the hyperparasitoid due to the diploid male vortex. However, regionally it persists because spatial structure allows for efficient local genetic rescue via balancing selection for rare alleles carried by immigrants. This is the first empirically based study of the possibility of the diploid male vortex in a natural host-parasitoid system.

气候变化可增强种群动态的空间同步性，引发大范围波动并破坏群落稳定性。营养级较高的物种（如寄生蜂（parasitoids））受影响尤为显著，因其依赖不稳定的寄主资源。多数寄生蜂具备互补性性别决定（complementary sex determination）机制，近交时会产生不育雄性，理论上可通过二倍体雄性漩涡（diploid male vortex）导致种群灭绝。本研究以栖息于大型破碎化景观中、具有空间结构的寄主种群内的重寄生蜂（hyperparasitoid）种群为研究对象，对该过程开展了实证检验。历经四年寄主蝴蝶集合种群（metapopulation）的剧烈波动，该寄生蜂的二倍体雄性产出率上升，有效种群规模（effective population size）急剧下降。我们构建的多营养级空间结构模型显示，寄主种群波动可通过二倍体雄性漩涡引发重寄生蜂的局域灭绝。但该物种在区域尺度上得以存续，这是因为空间结构允许迁入个体携带的稀有等位基因通过平衡选择实现高效的局域遗传拯救（genetic rescue）。本研究是首个在自然寄主-寄生蜂系统中针对二倍体雄性漩涡可能性开展的实证研究。