long post, mostly taxonomy. Skip along if you don't care about that.
There seems to be the mistaken impression that speciation stops the second humans become involved. If an animal is introduced to a new location, left to its own and manages to survive, it will eventually become a separate taxon from the original population through allopatric speciation. If this taxon is less 'valuable' because humans were involved at some point in its evolutionary history is a matter of discussion. Compare some island populations of agouti, Cozumel coati and dingo. The most recent major review of the Cervus (Rusa) timorensis subspecies, van Bemmel 1949 (or 1950, since worktime vs. publication has resulted in some confusion when people cite it, but it is a single publication), did document differences, mainly in skull and associated measurements but also in pelage, among the populations. This forms the basis for the seven widely quoted subspecies, including djonga from Muna and Buton island described by van Bemmel himself (e.g., Mammal Species of the World from 2005, and Handbook of the Mammals of the World v. 2 from 2011 both recognize the seven sspp). Several of these likely originate from populations that in ancient times were introduced by man. It has been argued that the differences documented by van Bemmel are trivial but as yet no one has provided a solution based on a sample that was even remotely as complete as his, or, better yet, used moden tecniques like DNA. Even if it appears most mammal taxonomists have overlooked that DNA can't be blindly trusted (ample example in Funk and Omland 2003, Species-level paraphyly and polyphyly: frequency, causes and consequences, with insights from animal mitochondrial DNA). In other words, jbnbsn99, what we are missing is not a study that documents differences between the populations (i.e., subspecies) because van Bemmel provided that. What we are missing is a study that refutes the evidence by van Bemmel. If we consider all Wallacean subspecies invalid solely because of their presumed introductory origin, the species name would likely also have to change to C. (R.) russa since the name timorensis would become indeterminable (assigned to a population that doesn't match any of the certainly native populations). The only other possibilities are to treat the species as monotypic (no difference between Bali and Java populations either) or get an ICZN ruling that allows the designation of a neotype of timorensis.
The question of introductions can be discussed too. Most recent authorities have specifically noted that Wallacean populations likely are the result of introductions. IUCN is one of the few recent authorities that have left out "likely", but the references they provide as a basis for the claim do include the uncertainty. IUCN correctly note, however, that "the Javan Rusa is an able swimmer (Kitchener et al. 1990), hindering determination of its native range". This uncertainty is also refleceted in Long 2003 (Introduced Mammals of the World). While the Wallace Line is of huge importance in zoogeography, it is not an impenetrable border. The Green Junglefowl, a species with a limited dispersal ability, is found on both sides. It has been argued that this also is the result of human introductions, but no evidence for this claim has been provided, and the main reason this theory was even coined was because of the perceived problem in having populations on both sides of W. Line. Of course I am sure we all know elephants also crossed the line, even if the dwarfs on Sulawesi and Flores died out before modern history. Interestingly, Flores and to a lesser extent parts of Sulawesi and Timor are also the only Wallacean locations with a relatively well documented fossil history, but certainly not to a level where I have heard anyone suggesting that every large Pleistocene mammal on the islands now is known from fossils. In summary, it seems highly likely that all Wallacean populations are the result of introductions, but saying it is a fact beyond all doubts doesn't really match the rather meagre published evidence.
). Put Javan rusa on the islands, blink your eyes (evolutionarily speaking), and you'll have Moluccan rusa again.
