Animal and Plant Sciences Department, University of Sheffield, Sheffield, UK.
School of Biological Sciences, University of Reading, Reading, UK.
Glob Chang Biol. 2020 May;26(5):2814-2828. doi: 10.1111/gcb.15015. Epub 2020 Mar 14.
Species interactions have a spatiotemporal component driven by environmental cues, which if altered by climate change can drive shifts in community dynamics. There is insufficient understanding of the precise time windows during which inter-annual variation in weather drives phenological shifts and the consequences for mismatches between interacting species and resultant population dynamics-particularly for insects. We use a 20 year study on a tri-trophic system: sycamore Acer pseudoplatanus, two associated aphid species Drepanosiphum platanoidis and Periphyllus testudinaceus and their hymenopteran parasitoids. Using a sliding window approach, we assess climatic drivers of phenology in all three trophic levels. We quantify the magnitude of resultant trophic mismatches between aphids and their plant hosts and parasitoids, and then model the impacts of these mismatches, direct weather effects and density dependence on local-scale aphid population dynamics. Warmer temperatures in mid-March to late-April were associated with advanced sycamore budburst, parasitoid attack and (marginally) D. platanoidis emergence. The precise time window during which spring weather advances phenology varies considerably across each species. Crucially, warmer temperatures in late winter delayed the emergence of both aphid species. Seasonal variation in warming rates thus generates marked shifts in the relative timing of spring events across trophic levels and mismatches in the phenology of interacting species. Despite this, we found no evidence that aphid population growth rates were adversely impacted by the magnitude of mismatch with their host plants or parasitoids, or direct impacts of temperature and precipitation. Strong density dependence effects occurred in both aphid species and probably buffered populations, through density-dependent compensation, from adverse impacts of the marked inter-annual climatic variation that occurred during the study period. These findings explain the resilience of aphid populations to climate change and uncover a key mechanism, warmer winter temperatures delaying insect phenology, by which climate change drives asynchronous shifts between interacting species.
物种相互作用具有时空成分，由环境线索驱动，如果这些线索因气候变化而改变，可能会导致群落动态发生变化。对于天气的年际变化如何驱动物候变化，以及这种变化对相互作用的物种及其种群动态产生的后果（尤其是昆虫），我们的理解还不够充分。我们使用了一个为期 20 年的三营养级系统研究：枫香树 Acer pseudoplatanus、两种相关的蚜虫 Drepanosiphum platanoidis 和 Periphyllus testudinaceus 及其膜翅目寄生蜂。使用滑动窗口方法，我们评估了所有三个营养级的物候学的气候驱动因素。我们量化了蚜虫与其植物宿主和寄生蜂之间的营养级不匹配的程度，然后模拟这些不匹配、直接天气效应和密度依赖性对当地蚜虫种群动态的影响。3 月中旬至 4 月下旬温暖的气温与枫香树萌芽、寄生蜂攻击和（略有）D. platanoidis 出现有关。春季天气推进物候的精确时间窗口在每个物种之间差异很大。至关重要的是，冬季后期温暖的气温延迟了两种蚜虫的出现。因此，季节变暖率的变化导致了营养级之间春季事件相对时间的显著变化，以及相互作用物种的物候不匹配。尽管如此，我们没有发现蚜虫种群增长率受到与宿主植物或寄生蜂的不匹配程度或温度和降水的直接影响的不利影响的证据。两种蚜虫都存在强烈的密度依赖性效应，可能通过密度依赖性补偿，缓冲了种群免受研究期间发生的明显年际气候变化的不利影响。这些发现解释了蚜虫种群对气候变化的恢复力，并揭示了一个关键机制，即温暖的冬季气温延迟昆虫物候，这是气候变化导致相互作用的物种之间异步变化的原因。
