Biological species concept
"The biological species concept has no bearing on asexual organisms, and has severe limitations in its application to other organisms. Endless time and effort can be expended on discussing the species concept, and devising yet further modifications and variations on proposed specific definitions. Such debates have great merit in encouraging more objective reasoning about evolution and taxonomy but, in the meantime, human predation and destruction of habitat continue to erase the subject species. Time is against us... Different species concepts produce [groups of subspecies], so it is futile to contemplate a definitive taxonomic system".