Department of Biological and Environmental Science, University of Helsinki, Helsinki, Finland.
J Evol Biol. 2011 Dec;24(12):2563-73. doi: 10.1111/j.1420-9101.2011.02379.x. Epub 2011 Sep 8.
Temporal resource fluctuations could affect the strength of antagonistic coevolution through population dynamics and costs of adaptation. We studied this by coevolving the prey bacterium Serratia marcescens with the predatory protozoa Tetrahymena thermophila in constant and pulsed-resource environments for approximately 1300 prey generations. Consistent with arms race theory, the prey evolved to be more defended, whereas the predator evolved to be more efficient in consuming the bacteria. Coevolutionary adaptations were costly in terms of reduced prey growth in resource-limited conditions and less efficient predator growth on nonliving resource medium. However, no differences in mean coevolutionary changes or adaptive costs were observed between environments, even though resource pulses increased fluctuations and mean densities of coevolving predator populations. Interestingly, a surface-associated prey defence mechanism (bacterial biofilm), to which predators were probably unable to counter-adapt, evolved to be stronger in pulsed-resource environment. These results suggest that temporal resource fluctuations can increase the asymmetry of antagonistic coevolution by imposing stronger selection on one of the interacting species.
时间资源波动可能通过种群动态和适应成本影响拮抗协同进化的强度。我们通过在恒定和脉冲资源环境中大约 1300 代共培养猎物细菌粘质沙雷氏菌和捕食性原生动物嗜热四膜虫来研究这一点。与军备竞赛理论一致，猎物进化得更具防御性，而捕食者进化得更有效地消耗细菌。共进化适应在资源有限的条件下降低了猎物的生长速度，并且在非生物资源培养基上捕食者的生长效率较低，这是有代价的。然而，即使资源脉冲增加了共进化捕食种群的波动和平均密度，在环境之间也没有观察到平均共进化变化或适应性成本的差异。有趣的是，一种表面相关的猎物防御机制（细菌生物膜）进化得更强，而捕食者可能无法对此进行反适应，这种防御机制在脉冲资源环境中进化得更强。这些结果表明，时间资源波动可以通过对相互作用的物种之一施加更强的选择，增加拮抗协同进化的不对称性。
