Jiang Lin, Schofield Oscar M E, Falkowski Paul G
Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey 08901, USA.
Am Nat. 2005 Oct;166(4):496-505. doi: 10.1086/444442. Epub 2005 Aug 5.
We present a simple nutrient-phytoplankton-zooplankton (NPZ) model that incorporates adaptive evolution and allometric relations to examine the patterns and consequences of adaptive changes in plankton body size. Assuming stable environmental conditions, the model makes the following predictions. First, phytoplankton should evolve toward small sizes typical of picoplankton. Second, in the absence of grazers, nutrient concentration is minimized as phytoplankton reach their fitness maximum. Third, increasing nutrient flux tends to increase phytoplankton cell size in the presence of phytoplankton-zooplankton coevolution but has no effect in the absence of zooplankton. Fourth, phytoplankton reach their fitness maximum in the absence of grazers, and the evolutionary nutrient-phytoplankton system has a stable equilibrium. In contrast, phytoplankton may approach their fitness minimum in the evolutionary NPZ system where phytoplankton and zooplankton are allowed to coevolve, which may result in oscillatory (unstable) dynamics of the evolutionary NPZ system, compared with the otherwise stable nonevolutionary NPZ system. These results suggest that evolutionary interactions between phytoplankton and zooplankton may have contributed to observed changes in phytoplankton sizes and associated biogeochemical cycles over geological time scales.
我们提出了一个简单的营养物-浮游植物-浮游动物（NPZ）模型，该模型纳入了适应性进化和异速生长关系，以研究浮游生物体型适应性变化的模式和后果。假设环境条件稳定，该模型做出以下预测。第一，浮游植物应朝着典型的微微型浮游生物的小体型进化。第二，在没有捕食者的情况下，随着浮游植物达到其适应度最大值，营养物浓度降至最低。第三，在浮游植物-浮游动物共同进化的情况下，增加营养物通量往往会增加浮游植物细胞大小，但在没有浮游动物的情况下则没有影响。第四，在没有捕食者的情况下，浮游植物达到其适应度最大值，并且进化的营养物-浮游植物系统具有稳定的平衡。相比之下，在允许浮游植物和浮游动物共同进化的进化NPZ系统中，浮游植物可能接近其适应度最小值，与原本稳定的非进化NPZ系统相比，这可能导致进化NPZ系统出现振荡（不稳定）动态。这些结果表明，浮游植物和浮游动物之间的进化相互作用可能促成了地质时间尺度上观察到的浮游植物大小变化以及相关的生物地球化学循环。
