Data from: Local adaptation of fish consumers alters primary production through changes in algal community composition and diversity

Ecological research has focused on understanding how changes in consumer abundance affect community structure and ecosystem processes. However, there is increasing evidence that evolutionary changes in consumers can also alter community structure and ecosystem processes. Typically, the effects of consumer phenotype on communities and ecosystem processes are measured as net effects that integrate numerous ecological pathways. Here, we analyze new data from experimental manipulations of Trinidadian guppy Poecilia reticulata presence, density and phenotype to examine how effects on the algal community cause changes in gross-primary production (GPP). We combine analytical tools borrowed from path analysis with experimental exclosures in mesocosms to separate the ecological and evolutionary effects of guppies into direct and indirect components. We show that the evolutionary effects of guppy phenotype act through different ecological pathways than the effects of guppy presence and density on GPP. As reported in previous studies that used a different measure of algal biomass, adding guppies and doubling their densities decreased algal biovolume through direct effects. In contrast to these previously reported results, exchanging guppy phenotypes that live without predators for phenotypes that live with predators did not affect algal biovolume. Instead, guppies from populations that live with predators increased the diversity of algal species and increased GPP compared to guppies that live without predators. These changes in the algal community were driven primarily by guppy phenotypes that live with predators—algal communities in mesocosms without fish were similar to those with guppies from predator-free locations, but both were different from mesocosms with guppies from populations that live with predators. Changes in the algal community were driven directly by differences in foraging behavior between the two consumer phenotypes. We reconcile these results with our previous findings, thereby enhancing our understanding of the relationship between ecological and evolutionary processes.生态学研究长期致力于解析消费者丰度变化对群落结构与生态系统过程的影响机制。然而，越来越多的研究证据表明，消费者的进化改变同样能够改变群落结构与生态系统过程。通常，消费者表型对群落及生态系统过程的影响被量化为整合了多条生态途径的净效应。本研究基于对特立尼达孔雀花鳉（Poecilia reticulata）的存在状态、种群密度及表型开展的实验操控所获得的新数据，探究其对藻类群落的影响如何引发总初级生产力（gross-primary production, GPP）的变化。我们结合源自路径分析（path analysis）的分析方法与中型实验生态箱（mesocosms）中的实验排除装置，将孔雀花鳉的生态效应与进化效应拆解为直接组分与间接组分。研究结果表明，孔雀花鳉表型的进化效应所途经的生态途径，与其存在状态及密度对GPP的影响途径存在显著差异。正如此前采用不同藻类生物量测量方法的研究所报道的，添加孔雀花鳉并将其种群密度翻倍，会通过直接效应降低藻类生物体积。与上述既往研究结果不同的是，将无捕食者环境下的孔雀花鳉表型替换为有捕食者环境下的表型，并未对藻类生物体积产生显著影响。与之相反，相较于无捕食者环境下的孔雀花鳉，来自有捕食者种群的孔雀花鳉能够提升藻类物种多样性与总初级生产力。藻类群落的这些变化主要由有捕食者环境下的孔雀花鳉表型所驱动：无鱼类的中型实验生态箱内的藻类群落，与放置了无捕食者区域来源的孔雀花鳉的生态箱内的藻类群落相似，但二者均与放置了有捕食者种群来源的孔雀花鳉的生态箱存在显著差异。藻类群落的变化直接由两类消费者表型间的觅食行为差异所驱动。我们将本研究结果与既往发现进行了整合，由此加深了对生态过程与进化过程间关联的认知。