Lieberman Daniel E, Hall Brian K
Department of Anthropology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA.
Novartis Found Symp. 2007;284:1-19; discussion 110-5. doi: 10.1002/9780470319390.ch1.
Recent developments in evolutionary biology have conflicting implications for our understanding of the developmental bases of microevolutionary processes. On the one hand, Darwinian theory predicts that evolution occurs mostly gradually and incrementally through selection on small-scale, heritable changes in phenotype within populations. On the other hand, many discoveries in evolutionary developmental biology--quite a few based on comparisons of distantly related model organisms--suggest that relatively simple transformations of developmental pathways can lead to dramatic, rapid change in phenotype. Here I review the history of and bases for gradualist versus punctuationalist views from a developmental perspective, and propose a framework with which to reconcile them. Notably, while tinkering with developmental pathways can underlie large-scale transformations in body plan, the phenotypic effect of these changes is often modulated by the complexity of the genetic and epigenetic contexts in which they develop. Thus the phenotypic effects of mutations of potentially large effect can manifest themselves rapidly, but they are more likely to emerge more incrementally over evolutionary time via transitional forms as natural selection within populations acts on their expression. To test these hypotheses, and to better understand how developmental shifts underlie microevolutionary change, future research needs to be directed at understanding how complex developmental networks, both genetic and epigenetic, structure the phenotypic effects of particular mutations within populations of organisms.
进化生物学的最新进展对于我们理解微观进化过程的发育基础有着相互矛盾的影响。一方面,达尔文理论预测进化主要通过对种群内表型的小规模、可遗传变化进行选择而逐渐地、渐进地发生。另一方面,进化发育生物学中的许多发现——其中不少是基于对远缘相关模式生物的比较——表明发育途径相对简单的转变能够导致表型的剧烈、快速变化。在此,我从发育的角度回顾渐变论与间断平衡论观点的历史及依据,并提出一个调和二者的框架。值得注意的是,虽然对发育途径的微调可能是身体结构大规模转变的基础,但这些变化的表型效应常常受到其发生时遗传和表观遗传背景复杂性的调节。因此,具有潜在重大影响的突变的表型效应可能迅速显现,但随着种群内的自然选择作用于其表达,它们更有可能在进化时间里通过过渡形式以更渐进的方式出现。为了检验这些假设,并更好地理解发育转变如何构成微观进化变化的基础,未来的研究需要致力于理解复杂的遗传和表观遗传发育网络如何构建生物种群内特定突变的表型效应。