浅析物种概念的演变历史

A brief review on the historical changes in the concept of species

本文是一篇关于物种概念演变的简述。生物学家用不同的方法或标准划分物种,就形成了不同的物种概念,如生物学物种、形态学物种、生态学物种、进化物种、系统发生或支序物种,或它们的组合,等等。它们都揭示了物种属性的特定侧面,都是不同物种客观存在的真实反映,但都无法令所有人满意。对真核生物来说,无论它们在形态上的差别有多大,生殖隔离(不能产生可育的后代)应该是两个群体能否真正分化成不同物种的关键,这种隔离机制可以是地理的、行为的或其他方式;而生殖隔离总会伴随着一些形态或遗传上的变化,虽然这些特征可能与生殖隔离本身并无多大关系,但往往成为分类学家或分子进化生物学家区分种的依据,对已经灭绝的化石物种来说,生殖隔离的物种划分方式就无能为力了。如何准确定义一个物种依然充满着矛盾,因为基于生殖隔离的物种概念不实用,而实用的物种概念(如形态学物种)又被认为是人为的。

This is a mini-review on the historical changes in the concept of species. Biologists use different methods or criteria to discriminate species, leading to the formation of different species concepts, e.g. biological species, morphospecies, ecological species, evolutionary species, phylogenetic/cladistic species, or their combinations. These concepts respectively reveal a specific profile of the species＇ attributes, as well as reflecting the objective existence of these creatures as different species, but not being satisfied with everyone. For eukaryotes, reproductive isolation （incapable of reproducing fertile offspring） should be the key for two populations to differentiate into two different species, no matter how much they differ morphologically. The mechanisms underlying such isolation might be geographical, behavioral, or otherwise. Reproductive isolation is certainly accompanied by some morphological or genetic changes that are often used as criteria by taxonomists or molecular evolutionary biologists to distinguish species, although these attributes may not be associated with reproductive isolation itself. Extinct species known only from fossils are impossible to be classified taxonomically according to reproductive isolation. The exact definition of the term ＂species＂ is still controversial, as a species concept based on reproductive isolation is usually not applicable, but a usable species definition （e.g. morphospecies） is regarded to be artificial. Key words： species concept; biological species; morphospecies; reproductive isolation