Tree phylogenetic diversity promotes host– parasitoid interactions

Michael - 2016- Tree phylogenetic diversity promotes host–parasitoid interactions.pdf

Abstract

Evidence from grassland experiments suggests that a plant community's phylogenetic diversity (PD) is a strong predictor of ecosystem processes, even stronger than species richness per se. This has, however, never been extended to species-rich forests and host–parasitoid interactions. We used cavity-nesting Hymenoptera and their parasitoids collected in a subtropical forest as a model system to test whether hosts, parasitoids, and their interactions are influenced by tree PD and a comprehensive set of environmental variables, including tree species richness. Parasitism rate and parasitoid abundance were positively correlated with tree PD. All variables describing parasitoids decreased with elevation, and were, except parasitism rate, dependent on host abundance. Quantitative descriptors of host–parasitoid networks were independent of the environment. Our study indicates that host–parasitoid interactions in species-rich forests are related to the PD of the tree community, which influences parasitism rates through parasitoid abundance. We show that effects of tree community PD are much stronger than effects of tree species richness, can cascade to high trophic levels, and promote trophic interactions. As during habitat modification phylogenetic information is usually lost non-randomly, even species-rich habitats may not be able to continuously provide the ecosystem process parasitism if the evolutionarily most distinct plant lineages vanish.

摘要：

草原试验的证据表明：和物种丰富度相比，植物群落系统发育多样性可以较好揭示生态系统功能。但是，这个推论从未推广到物种丰富的森林和寄主－拟寄生蜂物种互作关系中。我们用亚热带森林中的穴居膜翅目昆虫作为模式系统，研究寄主、拟寄生蜂和它们之间的互作关系是否受到树种系统发育多样性、物种丰富度等一组环境因子的影响。寄生率和寄生蜂多度和树种系统发育多样性正相关。所有拟寄生蜂相关的参数，除了寄生率，均随海拔升高下降，并依赖于寄主多度。寄主－拟寄生蜂网络的量化指标和环境无关。我们的研究表明：物种丰富的森林中，寄主－拟寄生蜂物种互作和群落中树种系统发育多样性有关，通过拟寄生蜂多度影响寄生率。我们的研究结果表明：树种的系统发育多样性比树种丰富度具有更强的影响，并会对高级营养水平产生连带影响，从而促进营养级的互作。在生境变化的过程中，系统发育信息通常发生非随机性丢失。如果进化中最明确的植物支系丢失，物种丰富的生境也难以提供寄生的生态系统功能。