Data from: Ontogeny tends to recapitulate phylogeny in digital organisms

Biologists have long debated whether ontogeny recapitulates phylogeny and, if so, why. Two plausible explanations are that (i) changes to early developmental stages are selected against because they tend to disrupt later development and (ii) simpler structures often precede more complex ones in both ontogeny and phylogeny if the former serve as building blocks for the latter. It is difficult to test these hypotheses experimentally in natural systems, so we used a computational system that exhibits evolutionary dynamics. We observed that ontogeny does indeed recapitulate phylogeny; traits that arose earlier in a lineage’s history also tended to be expressed earlier in the development of individuals. The relative complexity of traits contributed substantially to this correlation, but a significant tendency toward recapitulation remained even after accounting for trait complexity. This additional effect provides evidence that selection against developmental disruption also contributed to the conservation of early stages in development.长期以来，生物学家始终围绕个体发生（ontogeny）是否重演系统发生（phylogeny）这一问题展开争论，以及若果真如此，其背后的原因究竟为何。目前存在两种颇具合理性的解释：其一，早期发育阶段的改变往往会干扰后续发育进程，因此这类改变会遭到自然选择的淘汰；其二，若早期结构可作为后期复杂结构的构建模块，那么无论是在个体发生还是系统发生过程中，结构的演化通常都会遵循从简单到复杂的顺序。由于在自然生物系统中难以通过实验手段验证这些假说，我们选用了一个可展现进化动力学（evolutionary dynamics）特征的计算系统展开研究。我们的观测结果证实，个体发生确实会重演系统发生：在物种谱系的演化历史中出现得更早的性状，往往也会在个体发育的更早阶段得以表达。性状的相对复杂度对这一相关性具有显著贡献，但即便在统计上控制了性状复杂度这一变量之后，个体发生重演系统发生的显著趋势依然存在。这一额外效应表明，针对发育紊乱的自然选择，同样推动了早期发育阶段的演化保守性。