Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65, 00014 Helsinki, Finland.
Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, 114 18, Sweden.
Proc Biol Sci. 2018 Aug 22;285(1885):20180372. doi: 10.1098/rspb.2018.0372.
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 (DMV). 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 because of the DMV. However, regionally it persists because spatial structure allows for efficient local genetic rescue via balancing selection for rare alleles carried by immigrants. This is, to our knowledge, the first empirically based study of the possibility of the DMV in a natural host-parasitoid system.
气候变化会增加种群动态的空间同步性，导致大规模波动，使群落不稳定。高营养级物种，如寄生蜂，受到的影响不成比例，因为它们依赖不稳定的资源。大多数寄生蜂具有互补性别决定，当近亲繁殖时会产生不育的雄性，这理论上可以通过二倍体雄性涡旋（DMV）导致种群灭绝。我们使用栖息在大型破碎景观中具有空间结构的宿主种群中的一种超寄生蜂种群，从经验上检验了这个过程。在四年的高宿主蝴蝶复合种群波动中，寄生蜂的二倍体雄性产生增加，有效种群规模急剧下降。我们的多营养级空间结构模型表明，由于 DMV，宿主种群波动会导致超寄生蜂的局部灭绝。然而，在区域上它是持续存在的，因为空间结构允许通过对携带稀有等位基因的移民进行平衡选择，有效地进行局部遗传拯救。据我们所知，这是首次在自然宿主-寄生系统中对 DMV 可能性的实证研究。
