Torchin Mark E, Miura Osamu, Hechinger Ryan F
Ecology. 2015 Nov;96(11):3033-42. doi: 10.1890/15-0518.1.
Although the latitudinal diversity gradient is a well-known and general pattern, the mechanisms structuring it remain elusive. Two key issues limit differentiating these. First, habitat type usually varies with latitude, precluding a standardized evaluation of species richness. Second, broad-scale and local factors hypothesized to shape diversity patterns covary with one another, making it difficult to tease apart independent effects. Examining communities of parasites in widely distributed hosts can eliminate some of these confounding factors. We quantified diversity and interspecific interactions for trematode parasites infecting two similar snail species across 27 degrees of latitude from 43 locations in tropical and temperate oceans. Counter to typical patterns, we found that species richness, levels of parasitism, and intensity of intraguild predation increased with latitude. Because speciation rates are precluded from driving diversity gradients in this particular system, the reversed gradients are likely due to local ecological factors, specifically, increased productivity and stability. We highlight how this system may serve as a useful tool to provide insight into what processes drive diversity gradients in general.
尽管纬度多样性梯度是一种广为人知的普遍模式，但其形成机制仍不明确。有两个关键问题限制了对这些机制的区分。第一，栖息地类型通常随纬度变化，这使得对物种丰富度的标准化评估变得不可能。第二，被认为塑造多样性模式的大尺度和局部因素彼此相互关联，使得难以区分独立效应。研究广泛分布宿主中的寄生虫群落可以消除其中一些混杂因素。我们对感染两种相似蜗牛物种的吸虫寄生虫的多样性和种间相互作用进行了量化，这些蜗牛分布在热带和温带海洋的43个地点，跨越27个纬度。与典型模式相反，我们发现物种丰富度、寄生水平和 guild内捕食强度随纬度增加。由于在这个特定系统中物种形成速率不可能驱动多样性梯度，这种反转的梯度可能是由于局部生态因素，具体来说，是生产力和稳定性的增加。我们强调这个系统如何可以作为一个有用的工具，以深入了解一般情况下驱动多样性梯度的过程。
