Heard S B, Mooers A O
Department of Biological Sciences, University of Iowa, Iowa City 52242, USA.
Proc Biol Sci. 2000 Mar 22;267(1443):613-20. doi: 10.1098/rspb.2000.1046.
If we are to plan conservation strategies that minimize the loss of evolutionary history through human-caused extinctions, we must understand how this loss is related to phylogenetic patterns in current extinction risks and past speciation rates. Nee & May (1997, Science 278, 692-694) showed that for a randomly evolving clade (i) a single round of random extinction removed relatively little evolutionary history, and (ii) extinction management (choosing which taxa to sacrifice) offered only marginal improvement. However, both speciation rates and extinction risks vary across lineages within real clades. We simulated evolutionary trees with phylogenetically patterned speciation rates and extinction risks (closely related lineages having similar rates and risks) and then subjected them to several biologically informed models of extinction. Increasing speciation rate variation increases the extinction-management pay-off. When extinction risks vary among lineages but are uncorrelated with speciation rates, extinction removes more history (compared with random trees), but the difference is small. When extinction risks vary and are correlated with speciation rates, history loss can dramatically increase (negative correlation) or decrease (positive correlation) with speciation rate variation. The loss of evolutionary history via human-caused extinctions may therefore be more severe, yet more manageable, than first suggested.
如果我们要制定保护策略，以尽量减少因人为导致的物种灭绝而造成的进化史损失，我们就必须了解这种损失是如何与当前灭绝风险和过去物种形成速率中的系统发育模式相关联的。尼和梅（1997年，《科学》278卷，692 - 694页）表明，对于一个随机进化的分支来说，（i）一轮随机灭绝所消除的进化史相对较少，并且（ii）灭绝管理（选择牺牲哪些分类群）仅能带来些许改善。然而，在真实的分支中，物种形成速率和灭绝风险在不同谱系间是变化的。我们模拟了具有系统发育模式化的物种形成速率和灭绝风险（亲缘关系相近的谱系具有相似的速率和风险）的进化树，然后让它们接受几种基于生物学知识的灭绝模型。物种形成速率变化的增加会提高灭绝管理的回报。当灭绝风险在谱系间变化但与物种形成速率不相关时，灭绝会消除更多的历史（与随机树相比），但差异较小。当灭绝风险变化且与物种形成速率相关时，历史损失可能会随着物种形成速率的变化而显著增加（负相关）或减少（正相关）。因此，通过人为导致的物种灭绝造成的进化史损失可能比最初认为的更为严重，但也更易于管理。
