Martindale Mark Q, Finnerty John R, Henry Jonathan Q
Kewalo Marine Lab, University of Hawaii, 41 Ahui St., Honolulu, HI 96813, USA.
Mol Phylogenet Evol. 2002 Sep;24(3):358-65. doi: 10.1016/s1055-7903(02)00208-7.
The apparent conservation of cellular and molecular developmental mechanisms observed in a handful of bilaterian metazoans has spawned a "race" to reconstruct the bilaterian ancestor. Knowledge of this ancestor would permit us to reconstruct the evolutionary changes that have occurred along specific bilaterian lineages. However, comparisons among extant bilaterians provide an unnecessarily limited view of the ancestral bilaterian. Since the original bilaterians are believed by many to be derived from a radially symmetrical ancestor, additional evidence might be obtained by examining present-day radially symmetrical animals. We briefly review pertinent features of the body plans of the extant radial eumetazoan phyla, the Cnidaria, and Ctenophora, in the context of revealing potential evolutionary links to the bilaterians.
在少数两侧对称后生动物中观察到的细胞和分子发育机制的明显保守性引发了一场重建两侧对称动物祖先的“竞赛”。了解这个祖先将使我们能够重建沿着特定两侧对称动物谱系发生的进化变化。然而，现存两侧对称动物之间的比较提供了对两侧对称动物祖先不必要的有限视角。由于许多人认为最初的两侧对称动物是从辐射对称的祖先演化而来的，通过研究当今的辐射对称动物可能会获得更多证据。我们简要回顾现存辐射对称真后生动物门（刺胞动物门和栉水母动物门）身体结构的相关特征，以揭示与两侧对称动物潜在的进化联系。
