Schubert Michael, Escriva Hector, Xavier-Neto José, Laudet Vincent
Laboratoire de Biologie Moléculaire de la Cellule, CNRS-UMR5161, INRA LA 1237, IFR 128 BioSciences Lyon-Gerland, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
Trends Ecol Evol. 2006 May;21(5):269-77. doi: 10.1016/j.tree.2006.01.009. Epub 2006 Feb 17.
One important question in evolutionary biology concerns the origin of vertebrates from invertebrates. The current consensus is that the proximate ancestor of vertebrates was an invertebrate chordate. Today, the invertebrate chordates comprise cephalochordates (amphioxus) and tunicates (each a subphylum in the phylum Chordata, which also includes the vertebrate subphylum). It was widely accepted that, within the chordates, tunicates represent the sister group of a clade of cephalochordates plus vertebrates. However, recent studies suggest that the evolutionary positions of tunicates and cephalochordates should be reversed, the implications of which are considered here. We also review the two major groups of invertebrate chordates and compare relative advantages (and disadvantages) of each as model systems for elucidating the origin of the vertebrates.
进化生物学中的一个重要问题涉及脊椎动物从无脊椎动物的起源。目前的共识是，脊椎动物的直接祖先是一种无脊椎脊索动物。如今，无脊椎脊索动物包括头索动物（文昌鱼）和被囊动物（二者均为脊索动物门中的一个亚门，脊索动物门还包括脊椎动物亚门）。人们普遍认为，在脊索动物中，被囊动物是头索动物和脊椎动物进化枝的姐妹群。然而，最近的研究表明，被囊动物和头索动物的进化位置应该颠倒，本文将探讨这一观点的影响。我们还将回顾无脊椎脊索动物的两大主要类群，并比较它们各自作为阐明脊椎动物起源的模型系统的相对优势（和劣势）。
