Cardillo M, Huxtable J S, Bromham L
Department of Zoology, University of Queensland, St Lucia, Australia.
J Evol Biol. 2003 Mar;16(2):282-8. doi: 10.1046/j.1420-9101.2003.00513.x.
What causes species richness to vary among different groups of organisms? Two hypotheses are that large geographical ranges and fast life history either reduce extinction rates or raise speciation rates, elevating a clade's rate of diversification. Here we present a comparative analysis of these hypotheses using data on the phylogenetic relationships, geographical ranges and life history of the terrestrial mammal fauna of Australia. By comparing species richness patterns to null models, we show that species are distributed nonrandomly among genera. Using sister-clade comparisons to control for clade age, we then find that faster diversification is significantly associated with larger geographical ranges and larger litters, but there is no evidence for an effect of body size or age at first breeding on diversification rates. We believe the most likely explanation for these patterns is that larger litters and geographical ranges increase diversification rates because they buffer species from extinction. We also discuss the possibility that positive effects of litter size and range size on diversification rates result from elevated speciation rates.
是什么导致不同生物类群的物种丰富度有所不同？有两种假说认为，较大的地理分布范围和较快的生活史要么降低灭绝率，要么提高物种形成率，从而提高一个进化枝的多样化速率。在此，我们利用澳大利亚陆生哺乳动物区系的系统发育关系、地理分布范围和生活史数据，对这些假说进行了比较分析。通过将物种丰富度模式与零模型进行比较，我们发现物种在属间的分布并非随机。然后，我们利用姐妹进化枝比较来控制进化枝年龄，发现更快的多样化与更大的地理分布范围和更大的窝仔数显著相关，但没有证据表明体型或首次繁殖年龄对多样化速率有影响。我们认为，对这些模式最有可能的解释是，更大的窝仔数和地理分布范围会提高多样化速率，因为它们能保护物种免于灭绝。我们还讨论了窝仔数和分布范围大小对多样化速率的积极影响可能是由物种形成率提高所致的可能性。
