Grice Marine Laboratory, Department of Biology, College of Charleston, 205 Fort Johnson Road, Charleston, South Carolina 29412, USA.
Ecology. 2013 Jan;94(1):18-24. doi: 10.1890/11-0873.1.
Many terrestrial and most marine herbivores have generalist diets, yet the role that evolutionary history plays in their foraging behaviors is poorly documented. On tropical hard-bottom reefs, generalist fishes and sea urchins readily consume seaweeds that produce lipophilic secondary metabolites. In contrast, herbivores on temperate reefs less commonly encounter seaweeds with analogous metabolites. This biogeographic pattern suggests that tropical herbivores should evolve greater feeding resistance to lipophilic defenses relative to temperate herbivores, but tests of this biogeographic pattern are rare. We offered lipophilic extracts from nine subtropical seaweeds at two concentrations to sea urchins (four subtropical and three cold-temperate populations) and quantified urchin feeding resistance. Patterns of feeding resistance toward lipophilic defenses were more similar within genera than across genera of urchins, indicating a substantial role for phylogenetic history in the feeding ecology of these generalist herbivores. The biogeographic origin of urchins also influenced feeding resistance, as subtropical species displayed greater feeding resistance than did temperate species. Similarly, a subtropical population of Arbacia punctulata had greater feeding resistance for Dictyota and Stypopodium extracts relative to temperate A. punctulata. We conclude that evolutionary history plays a more central role in the foraging ecology of generalist herbivores than is currently appreciated.
许多陆生和大多数海洋草食动物的食物种类都很广泛，但进化历史在它们的觅食行为中所起的作用却鲜有记录。在热带硬底礁区，杂食性鱼类和海胆很容易食用产生脂溶性次生代谢物的海藻。相比之下，温带礁区的草食动物则不太常见到具有类似代谢物的海藻。这种生物地理模式表明，与温带草食动物相比，热带草食动物应该进化出更强的摄食抵抗脂溶性防御的能力，但对这种生物地理模式的检验却很少。我们向海胆（四个亚热带和三个冷温带种群）提供了来自九种亚热带海藻的两种浓度的脂溶性提取物，并量化了海胆的摄食抵抗能力。在摄食抵抗脂溶性防御的模式方面，海胆属内的模式比属间的模式更为相似，这表明进化历史在这些杂食性草食动物的摄食生态学中起着重要作用。海胆的生物地理起源也影响了摄食抵抗能力，因为亚热带物种比温带物种表现出更强的摄食抵抗能力。同样，与温带的 A. punctulata 相比，亚热带的 A. punctulata 种群对 Dictyota 和 Stypopodium 提取物的摄食抵抗能力更强。我们的结论是，进化历史在杂食性草食动物的觅食生态学中起着比目前人们所认识到的更为核心的作用。
