Department of Biology, University of Padova, Via U. Bassi 58/B, I-35131 Padova, Italy.
Philos Trans R Soc Lond B Biol Sci. 2010 Feb 27;365(1540):631-40. doi: 10.1098/rstb.2009.0268.
Metazoan life cycles can be complex in different ways. A number of diverse phenotypes and reproductive events can sequentially occur along the cycle, and at certain stages a variety of developmental and reproductive options can be available to the animal, the choice among which depends on a combination of organismal and environmental conditions. We hypothesize that a diversity of phenotypes arranged in developmental sequence throughout an animal's life cycle may have evolved by genetic assimilation of alternative phenotypes originally triggered by environmental cues. This is supported by similarities between the developmental mechanisms mediating phenotype change and alternative phenotype determination during ontogeny and the common ecological condition that favour both forms of phenotypic variation. The comparison of transcription profiles from different developmental stages throughout a complex life cycle with those from alternative phenotypes in closely related polyphenic animals is expected to offer critical evidence upon which to evaluate our hypothesis.
后生动物的生命周期可以以不同的方式变得复杂。许多不同的表型和生殖事件可以沿着周期顺序发生，并且在某些阶段，动物可以有多种发育和生殖选择，而这些选择取决于生物和环境条件的组合。我们假设，通过对最初由环境线索触发的替代表型进行遗传同化，动物生命周期中按发育顺序排列的多种表型可能已经进化而来。这一假设得到了支持，因为在个体发育过程中介导表型变化的发育机制与替代表型的决定之间存在相似性，而且有利于这两种表型变异的共同生态条件也是如此。比较复杂生命周期中不同发育阶段的转录谱与近缘多态动物中替代表型的转录谱，有望为评估我们的假设提供关键证据。
