Houlahan J E, Currie D J, Cottenie K, Cumming G S, Ernest S K M, Findlay C S, Fuhlendorf S D, Gaedke U, Legendre P, Magnuson J J, McArdle B H, Muldavin E H, Noble D, Russell R, Stevens R D, Willis T J, Woiwod I P, Wondzell S M
Department of Biology, University of New Brunswick, P.O. Box 5050, Saint John, NB, Canada E2L 4L5.
Proc Natl Acad Sci U S A. 2007 Feb 27;104(9):3273-7. doi: 10.1073/pnas.0603798104. Epub 2007 Feb 21.
In population ecology, there has been a fundamental controversy about the relative importance of competition-driven (density-dependent) population regulation vs. abiotic influences such as temperature and precipitation. The same issue arises at the community level; are population sizes driven primarily by changes in the abundances of cooccurring competitors (i.e., compensatory dynamics), or do most species have a common response to environmental factors? Competitive interactions have had a central place in ecological theory, dating back to Gleason, Volterra, Hutchison and MacArthur, and, more recently, Hubbell's influential unified neutral theory of biodiversity and biogeography. If competitive interactions are important in driving year-to-year fluctuations in abundance, then changes in the abundance of one species should generally be accompanied by compensatory changes in the abundances of others. Thus, one necessary consequence of strong compensatory forces is that, on average, species within communities will covary negatively. Here we use measures of community covariance to assess the prevalence of negative covariance in 41 natural communities comprising different taxa at a range of spatial scales. We found that species in natural communities tended to covary positively rather than negatively, the opposite of what would be expected if compensatory dynamics were important. These findings suggest that abiotic factors such as temperature and precipitation are more important than competitive interactions in driving year-to-year fluctuations in species abundance within communities.
在种群生态学中，关于竞争驱动（密度依赖）的种群调节与诸如温度和降水等非生物影响的相对重要性，一直存在着根本性的争议。在群落层面也出现了同样的问题；种群数量主要是由同时出现的竞争者数量的变化（即补偿动态）驱动的，还是大多数物种对环境因素有共同的反应？竞争相互作用在生态理论中一直占据核心地位，可以追溯到格里森、沃尔泰拉、哈钦森和麦克阿瑟，以及最近哈贝尔有影响力的生物多样性和生物地理学统一中性理论。如果竞争相互作用在驱动种群数量的逐年波动中很重要，那么一个物种数量的变化通常应该伴随着其他物种数量的补偿性变化。因此，强大补偿力的一个必然结果是，平均而言，群落中的物种将呈负协变。在这里，我们使用群落协变的度量方法，来评估在一系列空间尺度上由不同分类群组成的41个自然群落中负协变的普遍程度。我们发现，自然群落中的物种倾向于呈正协变而非负协变，这与如果补偿动态很重要时所预期的情况相反。这些发现表明，在驱动群落内物种数量的逐年波动方面，温度和降水等非生物因素比竞争相互作用更重要。
