Developmental Modules & Evolvability: The Gastropod Foregut as a Model

为什么一些生物体群体从它们第一次出现以来就出现了爆炸性的多样性，而另一些生物体群体却在数百万年的时间里毫无变化？这个谜团是进化发育生物学新兴领域的一个核心问题，该领域不满足于传统观点，即自然选择作用于后代之间的随机、基因指定的变异，提供了物种如何进化的完整故事。尽管选择显然很重要，但进化发展生物学家强调，信息从基因型到表型的转移发生在发育和发育组织的过程中，可以影响作为选择原料产生的变异的数量和种类。流行的假说认为，在组织成半自主模块的发育系统中将发现最大程度的“进化性”，这些模块可以在不破坏整个复杂结构的发育完整性的情况下分离出不同的表型。这一假设在概念上很有吸引力，但它的有效性取决于找到能够证明高进化率与模块化发展组织之间联系的系统。

Why have some groups of organisms diversified explosively since their first appearance, while others have puttered along for millions of years without much change at all? This mystery is a core issue for the emerging field of Evolutionary Developmental Biology, which is dissatisfied with the traditional view that natural selection acting on random, genetically-specified variation among offspring provides the complete story about how species evolve. Although selection is clearly important, evolutionary developmental biologists emphasize that transfer of information from genotype to phenotype occurs via the process of development and developmental organization can influence the amount and kind of variation produced as raw material for selection. The prevailing hypothesis suggests that the greatest amount of ‘evolvability’ will be found among developmental systems organized into semi-autonomous modules that can spin off variant phenotypes without disrupting the developmental integrity of whole complex structures. This hypothesis is conceptually appealing but its validity depends on finding systems in which a link between high rates of evolution and a modular organization of development can be demonstrated.