Centre for the Study of Evolution, School of Biological Sciences, University of Sussex, Falmer, Brighton BN1 9QG, UK.
Integr Comp Biol. 2003 Feb;43(1):148-56. doi: 10.1093/icb/43.1.148.
Molecular data is ideal for exploring deep evolutionary history because of its universality, stochasticity and abundance. These features provide a means of exploring the evolutionary history of all organisms (including those that do not tend to leave fossils), independently of morphological evolution, and within a statistical framework that allows testing of evolutionary hypotheses. In particular, molecular data have an important role to play in examining hypotheses concerning the tempo and mode of evolution of animal body plans. Examples are given where molecular phylogenies have led to a re-examination of some fundamental assumptions in metazoan evolution, such as the immutability of early developmental characters, and the evolvability of bauplan characters. Molecular data is also providing a new and controversial timescale for the evolution of animal phyla, pushing the major divisions of the animal kingdom deep into the Precambrian. There have been many reasons to question the accuracy and precision of molecular date estimates, such as the failure to account for lineage-specific rate variation and unreliable estimation of rates of molecular evolution. While these criticisms have been largely countered by recent studies, one problem has remained a challenge: could temporal variation in the rate of molecular evolution, perhaps associated with "explosive" adaptive radiations, cause overestimation of diversification dates? Empirical evidence for an effect of speciation rate, morphological evolution or ecological diversification on rates of molecular evolution is examined, and the potential for rate-variable methods for molecular dating are discussed.
分子数据是探索深层进化历史的理想选择，因为它具有普遍性、随机性和丰富性。这些特征提供了一种方法，可以探索所有生物的进化历史（包括那些不易留下化石的生物），而不受形态进化的影响，并在允许检验进化假设的统计框架内进行。特别是，分子数据在检验有关动物身体计划进化速度和模式的假说方面具有重要作用。本文举例说明了分子系统发育在重新检验后生动物进化中的一些基本假设方面所起的作用，例如早期发育特征的不变性和图式特征的可进化性。分子数据还为动物门的进化提供了一个新的、有争议的时间尺度，将动物王国的主要分支推向了前寒武纪。人们有很多理由质疑分子日期估计的准确性和精度，例如未能解释谱系特异性速率变化以及分子进化速率的不可靠估计。尽管最近的研究在很大程度上反驳了这些批评，但一个问题仍然是一个挑战：分子进化速率的时间变化，也许与“爆炸性”适应性辐射有关，会不会导致多样化日期的高估？本文考察了物种形成率、形态进化或生态多样化对分子进化速率的影响的实证证据，并讨论了用于分子定年的速率可变方法的潜力。
