Steiner Christopher F, Masse Jordan
Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA.
F1000Res. 2013 Feb 12;2:43. doi: 10.12688/f1000research.2-43.v1. eCollection 2013.
Heterogeneity among prey in their susceptibility to predation is a potentially important stabilizer of predator-prey interactions, reducing the magnitude of population oscillations and enhancing total prey population abundance. When microevolutionary responses of prey populations occur at time scales comparable to population dynamics, adaptive responses in prey defense can, in theory, stabilize predator-prey dynamics and reduce top-down effects on prey abundance. While experiments have tested these predictions, less explored are the consequences of the evolution of prey phenotypes that can persist in both vulnerable and invulnerable classes. We tested this experimentally using a laboratory aquatic system composed of the rotifer Brachionus calyciflorus as a predator and the prey Synura petersenii, a colony-forming alga that exhibits genetic variation in its propensity to form colonies and colony size (larger colonies are a defense against predators). Prey populations of either low initial genetic diversity and low adaptive capacity or high initial genetic diversity and high adaptive capacity were crossed with predator presence and absence. Dynamics measured over the last 127 days of the 167-day experiment revealed no effects of initial prey genetic diversity on the average abundance or temporal variability of predator populations. However, genetic diversity and predator presence/absence interactively affected prey population abundance and stability; diversity of prey had no effects in the absence of predators but stabilized dynamics and increased total prey abundance in the presence of predators. The size structure of the genetically diverse prey populations diverged from single strain populations in the presence of predators, showing increases in colony size and in the relative abundance of cells found in colonies. Our work sheds light on the adaptive value of colony formation and supports the general view that genetic diversity and intraspecific trait variation of prey can play a vital role in the short-term dynamics and stability of planktonic predator-prey systems.
猎物在被捕食易感性方面的异质性是捕食者 - 猎物相互作用中一个潜在的重要稳定因素，它会降低种群振荡的幅度并提高猎物的总种群丰度。当猎物种群的微观进化反应发生在与种群动态相当的时间尺度上时，理论上猎物防御的适应性反应可以稳定捕食者 - 猎物动态，并减少对猎物丰度的自上而下的影响。虽然实验已经检验了这些预测，但对于猎物表型进化的后果，尤其是那些在易受攻击和不易受攻击类别中都能持续存在的表型进化后果，研究较少。我们使用一个实验室水生系统进行了实验测试，该系统由萼花臂尾轮虫作为捕食者和猎物彼得森合尾藻组成，彼得森合尾藻是一种形成群体的藻类，在形成群体的倾向和群体大小方面表现出遗传变异（较大的群体是对捕食者的一种防御）。初始遗传多样性低且适应能力低或初始遗传多样性高且适应能力高的猎物种群，在有捕食者和无捕食者的情况下进行杂交。在为期167天的实验的最后127天测量的动态结果显示，初始猎物遗传多样性对捕食者种群的平均丰度或时间变异性没有影响。然而，遗传多样性和捕食者的存在与否交互影响猎物种群的丰度和稳定性；在没有捕食者的情况下，猎物的多样性没有影响，但在有捕食者的情况下，它稳定了动态并增加了猎物的总丰度。在有捕食者的情况下，遗传多样的猎物种群的大小结构与单一菌株种群不同，表现为群体大小增加以及群体中细胞相对丰度增加。我们的工作揭示了群体形成的适应性价值，并支持了这样一种普遍观点，即猎物的遗传多样性和种内性状变异在浮游捕食者 - 猎物系统的短期动态和稳定性中可以发挥至关重要的作用。
