INFERRING THE RATES OF BRANCHING AND EXTINCTION FROM MOLECULAR PHYLOGENIES
INFERRING THE RATES OF BRANCHING AND EXTINCTION FROM MOLECULAR PHYLOGENIES
复制标题
DOI：
10.1111/j.1558-5646.1995.tb02306.x
复制
发表时间：
1995-08-01
期刊：
影响因子：
3.3
通讯作者：
IWASA, Y
中科院分区：
文献类型：
--
作者：
KUBO, T;IWASA, Y
分子生物学技术提供了现存分类群的祖先进化与估计的分支时间。在这里，我们研究了模式的祖先的分支（或分支发生）和灭绝的类群，假设分支过程与时间相关的速率产生的现存类群。(1)如果分支率B和灭绝率c是常数，则祖先谱系数随时间变化的半对数图不是直线，而是曲线，斜率向末端增加，这意味着祖先谱系在接近现在时分支率明显增加。通过计算机模拟检验了基于非线性拟合的B和c的估计。当B大于c时，分支率的估计值可用于大的种群发生，而灭绝率c的估计值由于偏差和方差较大而不可靠。(2)随着时间的推移，祖先谱系数量的半对数图的斜率逐渐减小，正如在基于DNA杂交数据的鸟类家族的进化中所观察到的那样，可以通过减少的分支率或增加的灭绝率来同样很好地解释。作为时间函数的许多对分枝率和灭绝率可以产生相同的祖先进化。(3)过去的爆炸性分支事件会表现为祖先血统数量的快速增加。相比之下，在短时间内发生的大灭绝，如果不伴随着分支率的增加，不会在当时的祖先谱系数量上产生任何快速变化。(4)导出了现存物种的祖先谱系数与过去物种的实际数目平行变化的条件。
Molecular techniques provide ancestral phylogenies of extant taxa with estimated branching times. Here we studied the pattern of ancestral phylogeny of extant taxa produced by branching (or cladogenesis) and extinction of taxa, assuming branching processes with time-dependent rates. (1) If the branching rate b and extinction rate c are constant, the semilog plot of the number of ancestral lineages over time is not a straight line but is curvilinear, with increasing slope toward the end, implying that ancestral phylogeny shows apparent increase in the branching rate near the present. The estimate of b and c based on nonlinear fitting is examined by computer simulation. The estimate of branching rate can be usable for a large phylogeny if b is greater than c, but the estimate of extinction rate c is unreliable because of large bias and variance. (2) Gradual decrease in the slope of the semilog plot of the number of ancestral lineages over time, as was observed in a phylogeny of bird families based on DNA hybridization data, can be explained equally well by either the decreasing branching rate or the increasing extinction rate. Infinitely many pairs of branching and extinction rates as functions of time can produce the same ancestral phylogeny. (3) An explosive branching event in the past would appear as a quick increase in the number of ancestral lineages. In contrast, mass extinction occurring in a brief period, if not accompanied by an increase in branching rate, does not produce any rapid change in the number of ancestral lineages at the time. (4) The condition in which the number of ancestral lineages of extant species changes in parallel with the actual number of species in the past is derived.