摘要
1. Recently, fresh attempts have been made to understand the mechanisms structuring species–body size distributions. Of these, the model developed by Brown, Marquet & Taper (1993) (BMT), which uses measures of resource acquisition and conversion to determine an optimal body size (M*) for a given assemblage, is potentially the most significant. Here, we examine the novelty of the model and some of its assumptions, and test its empirical predictions.
2. The BMT model is one of a suite of physiological/life-history models examining size at maturity. Such energetic or ‘physical’ approaches to body size evolution have a considerable modern history and continue to enjoy attention in physiological ecology and life-history theory.
3. Although mortality significantly influences life-history evolution and mostly precludes the evolution of a body size that maximizes reproductive power output, it is excluded from the BMT model. Likewise, the model assumes that power and not efficiency is maximized, although there are conditions where this is not likely to be the case. Furthermore, the BMT model assumes that resource acquisition and conversion are physiologically limited, although the importance of physiological limitation in ecology remains unclear.
4. Additional assumptions of the model include coincidence of the optimum body size of an individual and a species, when in many species this is not the case, and coincidence of the most speciose size class in an assemblage and the optimal body size. Similarly, the probable influence of differences in the scaling of various parameters at the intra- and interspecific levels are not addressed, nor are the impacts of discrepancies between phenotypic and genotypic optima.
5. The measures of resource acquisition and conversion used in the BMT model are not only problematic, but also limit the utility of the model. If the scaling constants and exponents of field metabolic rate minus basal metabolic are used as a measure of resource acquisition beyond maintenance needs, and those for intrinsic rate of increase (rmax) as a measure of resource conversion, the applicability of the model to other taxa can be extended.
6. Using these measures we show that the model continues to provide a reasonable prediction of M* for the terrestrial mammal assemblages of both North America and Australia. However, when taxonomic inclusiveness is reduced by removing eutherians from the Australian data set and by examining the predictions of the model with regard to diprotodonts only, the model fails to provide reasonable predictions of M*.
7. Given problems with the BMT model, but its clear ability to predict the modal body size of at least two terrestrial mammal assemblages, we suggest that there is considerable scope for exploring the relationships between resource acquisition and conversion at the level of the individual and energy partitioning between individuals in multispecies communities.
摘要译文
[1。最近，人们已经尝试了解构成物种 - 身体尺寸分布的机制。其中，Brown，Marquet＆Taper（1993）（BMT）开发的模型，其中使用资源获取和转换的措施来确定给定组合的最佳体尺寸（M *）可能是最重要的。这里，我们研究模型的新颖性及其一些假设，并测试其经验预测。 2。BMT模型是一套生理/生活史模型，检查成熟时的大小。身体尺寸演变的这种精力或“物理”的方法具有相当的现代历史，并继续在生理生态学和生命史理论中受到关注。 3。尽管死亡率显着影响生活史的演变，并且大部分排除了使生殖力最大化的身体尺寸的演变，但它被排除在BMT模型之外。同样，该模型假定权力而不是效率最大化，尽管在这种情况下情况可能不是这样。此外，BMT模型假定资源获取和转换在生理学上是有限的，尽管在生态学中生理限制的重要性仍然不清楚。 4。模型的其他假设包括个体和物种的最佳体尺的巧合，当在许多物种中情况并非如此时，以及一个组合中最具体的尺寸等级和最佳体型的巧合。同样的，没有解决在种内和种间水平上各种参数的缩放差异的可能影响，表型和基因型最佳值之间的差异的影响也不是。 5.骨髓移植模型中使用的资源获取和转换措施不仅存在问题，而且限制了该模型的效用。如果场外代谢率的标定常数和指数减去基础代谢被用作超出维护需求的资源获取的度量，以及作为资源转换量度的内在增长率（r max），可以扩展该模型对其他分类群的适用性。 6。利用这些方法，我们发现该模型继续为北美和澳大利亚的陆地哺乳动物组合提供M *的合理预测。然而，当通过从澳大利亚数据集中删除eutherians而减少分类学包容性并且通过仅检查关于二齿类型的模型的预测时，该模型未能提供M *的合理预测。 7.鉴于骨髓移植模型存在问题，但是其预测至少两个陆生哺乳动物组合的模态体尺寸的清晰能力，探索个体层面的资源获取与转化之间的关系以及多个物种群体中个体之间能量分配之间的关系具有相当大的空间。]
S. L. CHOWN[1] and K. J. GASTON[2]. The species–body size distribution: energy, fitness and optimality[J]. Functional Ecology, 1997,11(3): 365-375