Warwick R M, Clarke K R
Institute for Marine Environmental Research, NERC, Prospect Place, The Hoe, PL1 3DH, Plymouth, UK.
Oecologia. 1984 Jan;61(1):32-41. doi: 10.1007/BF00379085.
Species body size distributions from eight temperate benthic communities show a highly conservative pattern with two separate lognormal distributions, corresponding to the traditional categories of meiofauna and macrofauna. The meiofaunal mode occurs at a dry body weight of 0.64 μg and the macrofaunal mode at 3.2 mg, with a trough between them at 45 μg. It is suggested that there is a particular body size at which meiofaunal life-history and feeding traits can be optimised, and another for macrofaunal traits. As size departs in either direction (larger or smaller) from these optima, fewer species of the same size are able to co-exist. The split occurs at 45 μg because many life history and feeding characteristics switch more or less abruptly at about this body size, compromise traits being either non-viable or disadvantageous. Meiofauna and macrofauna therefore comprise two separate evolutionary units each with an internally coherent set of biological characteristics.The expression of this conservative pattern is modified by water depth: the proportion of macrofauna species increases from intertidal situations to deeper water, and it is suggested that mechanisms of resource partitioning and diversity maintainence in the meiofauna and macrofauna are affected differentially by sediment disturbance. Salinity does not affect this proportionality, and so does not differentially affect mechanisms for maintaining species diversity in any particular size category of animals. Meiofauna species size distributions may be modified in sandy sediments because of physical impositions on interstitial or burrowing lifestyles.Brief discussion of some implications of these observations includes speculations on the larval ecology of macrofauna, on gigantism in Antarctic invertebrates, and on the benthic Sheldon spectrum.
来自八个温带底栖生物群落的物种体型分布呈现出一种高度保守的模式，有两个独立的对数正态分布，分别对应于传统的小型底栖生物和大型底栖生物类别。小型底栖生物的众数出现在干体重0.64微克处，大型底栖生物的众数出现在3.2毫克处，两者之间在45微克处有一个低谷。研究表明，存在一个特定的体型，小型底栖生物的生活史和摄食特征可以在此体型下得到优化，大型底栖生物的特征则在另一个体型下得到优化。当体型从这些最优值向任何一个方向（更大或更小）偏离时，相同体型的物种能够共存的数量就会减少。这种划分发生在45微克处，因为许多生活史和摄食特征大约在这个体型时或多或少会突然转变，折衷的特征要么无法存活，要么不利。因此，小型底栖生物和大型底栖生物构成了两个独立的进化单元，每个单元都有一套内在连贯的生物学特征。这种保守模式的表现会因水深而改变：大型底栖生物物种的比例从潮间带到更深的水域会增加，有人认为小型底栖生物和大型底栖生物中资源分配和多样性维持的机制受到沉积物扰动的影响不同。盐度不会影响这种比例关系，因此也不会对维持任何特定体型类别的动物物种多样性的机制产生不同影响。在沙质沉积物中，小型底栖生物的物种体型分布可能会因对间隙或穴居生活方式的物理限制而改变。对这些观察结果的一些影响的简要讨论包括对大型底栖生物幼体生态学以及南极无脊椎动物巨型化和底栖谢尔登谱的推测。
