Gaillard Jean-Michel, Yoccoz Nigel G, Lebreton Jean-Dominique, Bonenfant Christophe, Devillard Sébastien, Loison Anne, Pontier Dominique, Allaine Dominique
Unité Mixte de Recherche 5558, Biométrie et Biologie Evolutive, Bâtiment 711, Université Claude Bernard Lyon 1, 43 boulevard du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Am Nat. 2005 Jul;166(1):119-23; discussion 124-8. doi: 10.1086/430330. Epub 2005 May 31.
Oli and Dobson proposed that the ratio between the magnitude and the onset of reproduction (F/ alpha ratio) allows one to predict the relative importance of vital rates on population growth rate in mammalian populations and provides a reliable measure of the ranking of mammalian species on the slow-fast continuum of life-history tactics. We show that the choice of the ratio F/ alpha is arbitrary and is not grounded in demographic theory. We estimate the position on the slow-fast continuum using the first axis of a principal components analysis of all life-history variables studied by Oli and Dobson and show that most individual vital rates perform as well as the F/ alpha ratio. Finally, we find, in agreement with previous studies, that the age of first reproduction is a reliable predictor of the ranking of mammalian populations along the slow-fast continuum and that both body mass and phylogeny markedly influence the generation time of mammalian species. We conclude that arbitrary ratios such as F/ alpha correlate with life-history types in mammals simply because life-history variables are highly correlated in response to allometric, phylogenetic, and environmental influences. We suggest that generation time is a reliable metric to measure life-history variation among mammalian populations and should be preferred to any arbitrary combination between vital rates.
奥利和多布森提出，繁殖量与繁殖开始时间的比率（F/α比率）能让人预测哺乳动物种群中生命率对种群增长率的相对重要性，并为衡量哺乳动物物种在慢-快连续生命史策略中的排名提供可靠指标。我们表明，F/α比率的选择是任意的，且并非基于人口统计学理论。我们使用奥利和多布森所研究的所有生命史变量的主成分分析的第一轴来估计在慢-快连续体上的位置，并表明大多数个体生命率与F/α比率的表现相当。最后，我们发现，与先前的研究一致，首次繁殖年龄是哺乳动物种群在慢-快连续体上排名的可靠预测指标，并且体重和系统发育都显著影响哺乳动物物种的世代时间。我们得出结论，诸如F/α这样的任意比率与哺乳动物的生命史类型相关，仅仅是因为生命史变量在异速生长、系统发育和环境影响下高度相关。我们建议世代时间是衡量哺乳动物种群生命史变异的可靠指标，并且应该优先于生命率之间的任何任意组合。
