Newman J A, Gibson D J, Parsons A J, Thornley J H M
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK.
Department of Plant Biology, Southern Illinois University, Carbondale, Illinois 62901-6509, USA.
J Anim Ecol. 2003 Jul;72(4):556-566. doi: 10.1046/j.1365-2656.2003.00725.x.
Experiments investigating the population responses of aphids to CO enrichment have yielded results suggesting that aphid populations will be both larger under elevated CO and that they will be smaller under elevated CO. Most studies have failed to reject the null hypothesis of no difference in population sizes due to atmospheric CO concentration. This diversity of results has led some investigators to conclude that aphid responses are not general, and that every aphid-plant interaction may be unique and unpredictable a priori. We use a single, general, mathematical model to consider the population responses of cereal aphids to grass grown under different CO concentrations. The model shows that it is possible to explain any of the three observed results: larger populations, smaller populations, or no difference, and that which of these three outcomes arises may depend critically on the interaction between aphid nitrogen requirements and the nitrogen fertility of the soil. The model also shows that the qualitative results will depend on how sensitive the aphid species is to increases in its own density. Past studies have shown that aphids increase their production of winged offspring in response to increasing aphid density. The model predicts that, in general, aphid species that have lower nitrogen requirements and that are less sensitive to their own density will be more likely to have larger populations in elevated CO compared to ambient CO. Differences between aphid species (and clones) in their nitrogen requirements and the strength of their density-dependent response have not been widely reported in the literature. Also, the nitrogen fertility of the soil has rarely been manipulated in experiments on aphid responses to rising CO levels. The model suggests that the diversity of population responses of aphids may be both understandable and predictable in the context of such an interaction.
研究蚜虫对二氧化碳浓度升高的种群反应的实验得出了相互矛盾的结果，有的结果表明在二氧化碳浓度升高的情况下蚜虫种群数量会增加，而有的结果则表明会减少。大多数研究未能推翻因大气二氧化碳浓度导致种群数量无差异的零假设。这种结果的多样性导致一些研究人员得出结论，蚜虫的反应并不具有普遍性，而且每一种蚜虫与植物的相互作用可能都是独特且无法预先预测的。我们使用一个单一的通用数学模型来考虑谷物蚜虫对在不同二氧化碳浓度下生长的草的种群反应。该模型表明，可以解释观察到的三种结果中的任何一种：种群数量增加、种群数量减少或无差异，而这三种结果中的哪一种出现可能关键取决于蚜虫对氮的需求与土壤氮肥力之间的相互作用。该模型还表明，定性结果将取决于蚜虫物种对自身密度增加的敏感程度。过去的研究表明，蚜虫会随着蚜虫密度的增加而增加有翅后代的产生。该模型预测，一般来说，与环境二氧化碳浓度相比，对氮需求较低且对自身密度不太敏感的蚜虫物种在二氧化碳浓度升高时更有可能拥有更大的种群数量。蚜虫物种（和克隆体）在氮需求和密度依赖反应强度方面的差异在文献中尚未得到广泛报道。此外，在关于蚜虫对二氧化碳水平上升反应的实验中，很少对土壤的氮肥力进行控制。该模型表明，在这种相互作用的背景下，蚜虫种群反应的多样性可能是可以理解和预测的。
