Is regional species diversity bounded or unbounded?
Is regional species diversity bounded or unbounded?
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DOI：
10.1111/j.1469-185x.2012.00245.x
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发表时间：
2013-02-01
影响因子：
10
通讯作者：
Cornell, Howard V.
中科院分区：
文献类型：
--
作者：
Cornell, Howard V.
人们提出了两个相互矛盾的假设来解释大规模的物种多样性模式和动态。无界假说提出，区域多样性仅取决于时间和多样化率，并且无限制地增加。有界假说提出，生态约束对区域多样性设置了上限，而多样性通常接近其极限。来自化石记录、系统发育分析、生物地理学和谱系多样化过程中表型差异的最新证据表明，多样性受到生态过程的限制，但很少是渐近的。生态位空间通常是未填充的，或者可以更精细地细分，但仍然允许共存，并且通常在达到生态极限之前创建新的生态位空间。随着时间的推移，多样性的阻尼增加是普遍的模式，这表明需要一个新的“阻尼增加假说”。阻尼增加假说预测，多样性通常会随着时间的推移而增加，但其增加速度往往会因生态限制而减慢。然而，由于生态位限制而导致的放缓必须与产生类似模式的其他可能机制区分开来。这些包括采样伪影、无法用某些方法检测灭绝或进化枝多样性下降、相关物种形成-灭绝动态的扭曲效应、异域物种形成的机会在空间和时间上发生变化的可能性，以及未被发现的天敌在减少寄主范围并从而减缓物种形成速率方面的作用。区域多样性研究的分类范围必须扩大到包括所有生态相似的物种，以便准确推断生态约束。阻尼增长假说表明，需要有关进化过程的信息，例如物种形成时间和内在多样化率以及生态因素，来解释为什么区域多样性随时间、地点和类群的不同而变化。
Two conflicting hypotheses have been proposed to explain large-scale species diversity patterns and dynamics. The unbounded hypothesis proposes that regional diversity depends only on time and diversification rate and increases without limit. The bounded hypothesis proposes that ecological constraints place upper limits on regional diversity and that diversity is usually close to its limit. Recent evidence from the fossil record, phylogenetic analysis, biogeography, and phenotypic disparity during lineage diversification suggests that diversity is constrained by ecological processes but that it is rarely asymptotic. Niche space is often unfilled or can be more finely subdivided and still permit coexistence, and new niche space is often created before ecological limits are reached. Damped increases in diversity over time are the prevalent pattern, suggesting the need for a new 'damped increase hypothesis'. The damped increase hypothesis predicts that diversity generally increases through time but that its rate of increase is often slowed by ecological constraints. However, slowing due to niche limitation must be distinguished from other possible mechanisms creating similar patterns. These include sampling artifacts, the inability to detect extinctions or declines in clade diversity with some methods, the distorting effects of correlated speciation-extinction dynamics, the likelihood that opportunities for allopatric speciation will vary in space and time, and the role of undetected natural enemies in reducing host ranges and thus slowing speciation rates. The taxonomic scope of regional diversity studies must be broadened to include all ecologically similar species so that ecological constraints may be accurately inferred. The damped increase hypothesis suggests that information on evolutionary processes such as time-for-speciation and intrinsic diversification rates as well as ecological factors will be required to explain why regional diversity varies among times, places and taxa.