Stone Adrian C, Gehring Catherine A, Cobb Neil S, Whitham Thomas G
Department of Biology, Metropolitan State University, Denver, CO, United States.
Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States.
Front Plant Sci. 2018 Dec 11;9:1831. doi: 10.3389/fpls.2018.01831. eCollection 2018.
Understanding how genetic-based traits of plants interact with climate to affect associated communities will help improve predictions of climate change impacts on biodiversity. However, few community-level studies have addressed such interactions. Pinyon pine () in the southwestern U.S. shows genetic-based resistance and susceptibility to pinyon needle scale (). We sought to determine if susceptibility to scale herbivory influenced the diversity and composition of the extended community of 250+ arthropod species, and if this influence would be consistent across consecutive years, an extreme drought year followed by a moderate drought year. Because scale insects alter the architecture of susceptible trees, it is difficult to separate the direct influences of susceptibility on arthropod communities from the indirect influences of scale-altered tree architecture. To separate these influences, scales were experimentally excluded from susceptible trees for 15 years creating susceptible trees with the architecture of resistant trees, hereafter referred to as scale-excluded trees. Five patterns emerged. (1) In both years, arthropod abundance was 3-4X lower on susceptible trees compared to resistant and scale-excluded trees. (2) Species accumulation curves show that alpha and gamma diversity were 2-3X lower on susceptible trees compared to resistant and scale-excluded trees. (3) Reaction norms of arthropod richness and abundance on individual tree genotypes across years showed genotypic variation in the community response to changes in climate. (4) The genetic-based influence of susceptibility on arthropod community composition is climate dependent. During extreme drought, community composition on scale-excluded trees resembled susceptible trees indicating composition was strongly influenced by tree genetics independent of tree architecture. However, under moderate drought, community composition on scale-excluded trees resembled resistant trees indicating traits associated with tree architecture became more important. (5) One year after extreme drought, the arthropod community rebounded sharply. However, there was a much greater rebound in richness and abundance on resistant compared to susceptible trees suggesting that reduced resiliency in the arthropod community is associated with susceptibility. These results argue that individual genetic-based plant-herbivore interactions can directly and indirectly impact community-level diversity, which is modulated by climate. Understanding such interactions is important for assessing the impacts of climate change on biodiversity.
了解植物基于遗传的性状如何与气候相互作用以影响相关群落，将有助于改进对气候变化对生物多样性影响的预测。然而，很少有群落层面的研究涉及此类相互作用。美国西南部的矮松（）对矮松球蚜（）表现出基于遗传的抗性和易感性。我们试图确定对球蚜食草作用的易感性是否会影响250多种节肢动物物种的扩展群落的多样性和组成，以及这种影响在连续几年（先是极端干旱年份，接着是中度干旱年份）是否一致。由于球蚜会改变易感树木的结构，因此很难将易感性对节肢动物群落的直接影响与球蚜改变的树木结构的间接影响区分开来。为了区分这些影响，在15年的时间里通过实验将球蚜从易感树木上排除，从而创造出具有抗性树木结构的易感树木，以下简称排除球蚜的树木。出现了五种模式。（1）在这两年中，与抗性树木和排除球蚜的树木相比，易感树木上的节肢动物丰度低3至4倍。（2）物种积累曲线表明，与抗性树木和排除球蚜的树木相比，易感树木上的α多样性和γ多样性低2至3倍。（3）多年来个体树木基因型上节肢动物丰富度和丰度的反应规范表明，群落对气候变化的反应存在基因型差异。（4）易感性对节肢动物群落组成的基于遗传的影响取决于气候。在极端干旱期间，排除球蚜的树木上的群落组成类似于易感树木，这表明组成受到树木遗传的强烈影响，与树木结构无关。然而，在中度干旱条件下，排除球蚜的树木上的群落组成类似于抗性树木，这表明与树木结构相关的性状变得更加重要。（5）极端干旱一年后，节肢动物群落急剧反弹。然而，与易感树木相比，抗性树木上的丰富度和丰度反弹幅度更大，这表明节肢动物群落恢复力的降低与易感性有关。这些结果表明，基于个体遗传的植物 - 食草动物相互作用可以直接和间接地影响群落层面的多样性，而这种多样性受气候调节。了解此类相互作用对于评估气候变化对生物多样性的影响很重要。
