物种概念及其界定

The median means of species concepts and species delimitation

关键词:  物种概念  物种界定  统一

Key words:  species concept  species delimitation  unified

摘要:

半世纪以来，物种概念的定义备受关注，不同研究方向的生物学家提出24种不同或至少有分歧的物种概念，根据其不同的物种概念，物种的界定和物种的数量会出现很大的差异。人们普遍认同：物种是进化分离的微居群谱系，但把谱系分离过程中获得的特征如生殖隔离、可鉴定性、单系统发生等视为鉴定物种次级特征却有不同的声音。该文提出统一的物种概念，把谱系进化分离作为物种界定的唯一而又必要的特征，把谱系分离过程中获得的次级特征作为界定谱系分离的证据。鉴于此，物种概念间的分歧就会化解。其一，物种概念化与物种界定明显分开，不再混淆；其二，谱系的次级特征只与物种界定有关，在某种程度上为谱系分离提供证据；第三，若能把合理解释的任何一个特征作为某物种客观存在的证据，这样更多的特征更能确定谱系分离；最后最重要的是，统一物种概念使我们解放思想，扬弃传统的物种界定标准，探求物种界定的新思路。

Abstract:

From the half century to now，the issue of species delimitation has long been confused by species conceptualization，according to controversy species concepts，the boundaries and numbers of species could be great difference. Alternative species concepts agree in treating existence as a separately evolving metapopulation lineage as the primary defining property of the species category，but adopting different properties acquired by lineages during the course of divergence(e.g.，intrinsic reproductive isolation，diagnosability，monophyly)as secondary species criteria causes different sounds. The paper gave a unified species concept treating a separately evolving metapopulation lineage as the only necessary property of species，and secondary species criteria as different lines of evidence relevant to assessing lineage separation. This unified concept of species had several consequences for species delimitation as follows: first，the issues of species conceptualization and species delimitation were clearly separated；the secondary species criteria were no longer considered relevant to species conceptualization but only to species delimitation. Second，all of the properties formerly treated as secondary species criteria were relevant to species delimitation to the extent that they provide evidence of lineage separation. Third，if possible，the presence of any one of the properties was evidence for the existence of a species，though more properties and thus more lines of evidence are associated with a higher degree of corroboration；Lastly，the unified species made ones liberate minds from the traditional species criteria，not tied to those properties，and develop new methods of species delimitation.