San Diego Zoo Safari Park Male northern white rhino in San Diego is dead.

Even if one follows the phylogenetic species concept, the distinctness of the northern white rhinoceros as a species is not settled. Not all populations that are monophyletic are treated as species - subspecies, for example, in many (most, if correctly identified) instances are monophyletic. It's all a matter of semantics - hence the ongoing debates between lumpers and splitters in taxonomic circles. In fact, the phylogenetic species concept often must rely on the biological species concept (i.e., reproductive isolation) when it comes to determining whether a given monophyletic population is considered a species, a subspecies, or a mere population. It's a matter of sematics. Hence the ongoing debate as to whether the distinct, reproductively isolated (in many cases), monophyletic populations of giraffe are best considered species or subspecies, or the splitting of orangutans into two species despite the ease of interbreeding when physical barriers between the two are removed.

In terms of conservation, the IUCN differs in its treatment of subspecies, only categorizing birds by species, but for mammals, assessing populations down to the subspecies level. Hence, the IUCN recognizes the northern white rhino as critically endangered, while the southern white (and the species as a whole) are assessed as near threatened. Because of IUCN's approach (and its authority), it seems (to me at least), less important for mammals than for other taxa as to whether or not a given population is considered a species or a subspecies. Yes, it may be that the loss of a species (however the term is defined) carries with it some greater weight, but at least the northern white is recognized as a distinct taxon worthy of conservation by the IUCN, so whether or not it's considered a species is not necessarily of the utmost importance.

 

Thanks for that. I was pretty uninformed on the subject.