Ernst Mayr有一套定義是講種是 "實際或者會當交配的自然族群群體,怹佮其他群體的生湠互相是獨立的" (groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups).[1]
↑Hanage, William P。 (April 2013). "Fuzzy species revisited". BMC Biology. 11 (41). 2013-04-22 khòaⁿ--ê. A coherent species concept that can be applied throughout the kingdoms of life is still elusive。