Adaptation to elevated CO2 in different biodiversity contexts

In the absence of migration, species persistence depends on adaption to a changing environment, but whether and how adaptation to global change is altered by community diversity is not understood. Community diversity may prevent, enhance or alter how species adapt to changing conditions by influencing population sizes, genetic diversity and/or the fitness landscape experienced by focal species. We tested the impact of community diversity on adaptation by performing a reciprocal transplant experiment on grasses that evolved for 14 years under ambient and elevated CO2, in communities of low or high species-richness. Using biomass as a fitness proxy, we find evidence for local adaptation to elevated CO2, but only for plants assayed in a community of similar diversity to the one experienced during the period of selection. Our results indicate that the biological community shapes the very nature of the fitness landscape within which species evolve in response to elevated CO2.在不存在迁移的情况下，物种的存续取决于对变化环境的适应，但群落多样性是否以及如何改变物种对全球变化的适应，目前尚未明确。群落多样性可通过影响目标物种的种群规模、遗传多样性以及其所经历的适合度景观（fitness landscape），阻碍、促进或改变物种适应环境变化的路径。本研究针对在低、高物种丰富度群落中，分别于环境CO2与升高CO2条件下演化14年的草本植物开展互惠移植实验（reciprocal transplant experiment），以此探究群落多样性对物种适应的影响。以生物量作为适合度替代指标，我们观测到草本植物对升高CO2产生局部适应的证据，但该现象仅出现在检测所用群落的多样性与演化选择阶段所处群落多样性一致的植株中。本研究结果表明，生物群落塑造了物种为响应升高CO2而演化的适合度景观的本质属性。