Alberch P, Blanco M J
Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.
Int J Dev Biol. 1996 Aug;40(4):845-58.
The concept of heterochrony derives from classical approaches to the study of ontogeny and phylogeny. Under the influence of landmark books by deBeer (1930) and Gould (1977), the traditional theories have been revised to fit into the conceptual framework of modern genetics and evolutionary theory. The current scheme, however, suffers from a problem of lack of precise definitions. The term heterochrony is now used to refer to a developmental process as well as to an evolutionary pattern. That is, it refers to a microevolutionary process of adaptation, operating in local populations under selection and to a macroevolutionary pattern based on undefined internal laws of form. Such conceptually contradictory frameworks are a source of confusion and of empirical misuse of concepts. We propose to reduce the dependence of current thinking about heterochrony on the concept of "timing" and instead focus on the organization of sequences of developmental events in ontogeny. Although Haeckelian views have been rejected, most experts would agree that some subtle parallelism between ontogeny and phylogeny does occur. This relationship deserves renewed attention and urodeles are particularly suited to study it due to their variable patterns of ontogeny and complex life cycles. Current reductionist attempts to apply the morphological terminology and postulates of classical heterochrony concepts to cellular and molecular (genetic) aspects of morphogenesis are problematic. Molecular heterochrony requires a linear or strictly hierarchical structure of gene regulation of development. In addition, isomorphism between genetic mutations and morphological changes would be required for the existing terminology to apply. Finally, we caution against a broad interpretation of heterochronic processes at the molecular level, since the approach may end up permitting the meaningless interpretation of any developmental change as heterochrony.
异时性的概念源于个体发育和系统发育研究的经典方法。在德比尔（1930年）和古尔德（1977年）具有里程碑意义的著作影响下，传统理论已被修订以适应现代遗传学和进化理论的概念框架。然而，当前的方案存在缺乏精确界定的问题。现在，异时性这个术语既用于指代一个发育过程，也用于指代一种进化模式。也就是说，它既指在选择作用下局部种群中运作的微观进化适应过程，也指基于未明确的形态内部规律的宏观进化模式。这种概念上相互矛盾的框架是造成混淆以及概念在实证中被误用的根源。我们提议减少当前关于异时性的思考对“时间安排”概念的依赖，转而关注个体发育中发育事件序列的组织。尽管海克尔的观点已被摒弃，但大多数专家会认同个体发育和系统发育之间确实存在一些微妙的平行关系。这种关系值得重新关注，而有尾两栖类动物因其个体发育模式多样且生命周期复杂，特别适合用于研究它。当前将经典异时性概念的形态学术语和假设应用于形态发生的细胞和分子（遗传）层面的还原论尝试存在问题。分子异时性需要发育基因调控的线性或严格分层结构。此外，现有术语若要适用，基因突变与形态变化之间需存在同构关系。最后，我们提醒不要对分子层面的异时过程进行宽泛解释，因为这种方法最终可能会允许将任何发育变化都无意义地解释为异时性。
