Nelson W A, McCauley E, Wrona F J
Department of Biological Sciences, Ecology Division, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
Proc Biol Sci. 2001 Jun 22;268(1473):1223-30. doi: 10.1098/rspb.2001.1652.
Recent work with the freshwater zooplankton Daphnia has suggested that the quality of its algal prey can have a significant effect on its demographic rates and life-history patterns. Predator-prey theory linking food quantity and food quality predicts that a single system should be able to display two distinct patterns of population dynamics. One pattern is predicted to have high herbivore and low algal biomass dynamics (high HBD), whereas the other is predicted to have low herbivore and high algal biomass dynamics (low HBD). Despite these predictions and the stoichiometric evidence that many phytoplankton communities may have poor access to food of quality, there have been few tests of whether a dynamic predator-prey system can display both of these distinct patterns. Here we report, to the authors' knowledge, the first evidence for two dynamical patterns, as predicted by theory, in a single predator-prey system. We show that the high HBD is a result of food quantity effects and that the low HBD is a result of food quality effects, which are maintained by phosphorus limitation in the predator. These results provide an important link between the known effects of nutrient limitation in herbivores and the significance of prey quality in predator-prey population dynamics in natural zooplankton communities.
近期对淡水浮游动物水蚤的研究表明，其藻类猎物的质量会对其种群动态率和生活史模式产生重大影响。将食物数量与食物质量联系起来的捕食者 - 猎物理论预测，单一系统应该能够呈现两种不同的种群动态模式。一种模式预计具有高食草动物和低藻类生物量动态（高HBD），而另一种模式预计具有低食草动物和高藻类生物量动态（低HBD）。尽管有这些预测以及化学计量学证据表明许多浮游植物群落可能难以获得优质食物，但对于动态捕食者 - 猎物系统是否能够呈现这两种不同模式的测试却很少。据作者所知，在此我们报告了单一捕食者 - 猎物系统中如理论所预测的两种动态模式的首个证据。我们表明，高HBD是食物数量效应的结果，而低HBD是食物质量效应的结果，后者由捕食者中的磷限制所维持。这些结果在食草动物中已知的营养限制效应与自然浮游动物群落中捕食者 - 猎物种群动态中猎物质量的重要性之间提供了重要联系。
