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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >EVOLUTIONARY CONSEQUENCES OF FOOD CHAIN LENGTH IN KELP FOREST COMMUNITIES
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EVOLUTIONARY CONSEQUENCES OF FOOD CHAIN LENGTH IN KELP FOREST COMMUNITIES

机译：海带森林社区食物链长的演变后果

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Kelp forests are strongly influenced by macroinvertebrate grazing on fleshy macroalgae. In the North Pacific Ocean, sea otter predation on macroinvertebrates substantially reduces the intensity of herbivory on macroalgae. Temperate Australasia, in contrast, has no known predator of comparable influence, These ecological and biogeographic patterns led us to predict that (i) the intensity of herbivory should be greater Tn temperate Australasia than in the North Pacific Ocean; thus (ii) Australasian seaweeds have been under stronger selection to evolve chemical defenses and (iii) Australasian herbivores have been more strongly selected to tolerate these compounds. We tested these predictions first by measuring rates of algal tissue loss to herbivory at several locations in Australasian and North Pacific kelp forests. There were significant differences in grazing rates among sea otter-dominated locations in the North Pacific (0-2% day(-1)), Australasia (5-7% day(-1)), and a North Pacific location lacking sea otters (80% day(-1)). The expectations that chronically high rates of herbivory in Australasia have selected for high concentrations of defensive secondary metabolites (phlorotannins) in brown algae and increased tolerance of these defenses in the herbivores also were supported. Phlorotannin concentrations in kelps and fucoids from Australasia were, on average, 5-6 times higher than those in a comparable suite of North Pacific algae, confirming earlier findings, Furthermore, feeding rates of Australasian herbivores were largely unaffected by phlorotannins, regardless of the compounds' regional source, North Pacific herbivores, in contrast, were consistently deterred by phlorotannins from both Australasia and the North Pacific, These findings suggest that top-level consumers, acting through food chains of various lengths, can strongly influence the ecology and evolution of plant-herbivore interactions. [References: 36]
机译：海带森林受到肉质大型藻类中大型无脊椎动物的强烈影响。在北太平洋，捕食大型无脊椎动物的水獭大大降低了大型藻类的食草性。相反，温带大洋洲没有已知的具有类似影响力的掠食者。这些生态和生物地理模式使我们预测：（i）草食性强度应比北太平洋大。因此（ii）对澳大利亚海藻进行了更严格的选择，以发展其化学防御作用；（iii）对澳大利亚草食性动物的选择更加强烈，以耐受这些化合物。我们首先通过测量在澳大利亚和北太平洋海带森林中多个地点的藻类组织对食草动物的损失率来测试这些预测。在北太平洋（0-2％day（-1）），大洋洲（5-7％day（-1））和北太平洋缺少海獭的地方，以水獭为主的地区之间的放牧率存在显着差异（80％天（-1））。在澳大利亚，长期以来高水平的草食动物选择了褐藻中高浓度的防御性次生代谢物（次膦酸单宁），并且对草食动物对这些防御物的耐受性得到了提高的期望也得到了支持。大洋洲海藻和海藻中的海藻单宁含量平均比北太平洋藻类高出5-6倍，这证实了较早的发现。此外，无论哪种化合物，澳大拉亚草食动物的进食速度基本上不受海藻单宁的影响。相比之下，来自北大洋和北太平洋的邻苯二酚始终抑制北太平洋草食动物的区域性来源。这些发现表明，顶级消费者通过各种长度的食物链起作用，可以强烈影响植物的生态和进化-草食动物的互动。 [参考：36]

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