Welcome to yet another article in the (outstandingly successful, yet recycled from ver 1) series on babirusas. Observant readers will have noticed that, strangely, I've refrained thus far from using a scientific binomial for babirusas, plus I've consistently (I think) referred to them in the plural, and not as a single species. What gives?
Well, the proverbial cat is already out of the bag, but the traditional taxonomy where all babirusas are referred to the single species Babyrousa babyrussa is now defunct and there are good reasons for recognising several species. Babirusa taxonomy was reviewed by Groves (1980) who recognised four subspecies, one of which (B. babyrussa bolabatuensis from south-eastern Sulawesi) was named for Holocene fossils and is apparently extinct. A fifth subspecies, B. babyrussa beruensis, is larger than the more recent forms and known only from Pleistocene fossils.
In more recent publications, however (Groves 2001, Meijaard & Groves 2002a, b), it has been argued that most of the supposed subspecies are distinct enough to be recognised as distinct species, being as different from one another as are universally recognised species within other artiodactyl groups [adjacent head shot from Babirusa.Org]. Whether taxa are awarded subspecific or specific rank is of course subjective, but not only is it (arguably) misleading to include all of these taxa within a single species, there is also the practical problem that species are always regarded as more deserving of conservation effort than subspecies. If this is news to you, or seems odd or just stupid, here is what William Oliver recently had to say about the subject...
I am not really sure why, but species are generally regarded as being somehow more important than subspecies and, hence, merit higher conservation priority. I confess I can't swallow this view without a good deal of choking and spluttering - particularly if one considers that a polytypic species - being an abstracted sum of its parts - doesn't actually exist. In fact, the adoption of this view can be (and often is) positively unhelpful, in that subspecies are all too often ignored and species' conservation priorities are thus 'loaded' in favour of the least threatened subspecies or populations - a patently ridiculous (and arguably irresponsible) situation' (Oliver 2001, p. 4).
Whether there are political reasons for raising 'subspecies' to specific status or not, it is still clear that the named babirusa taxa are quite distinct from one another. The species are...
-- B. babyrussa Linnaeus, 1758: a small species, with long, thick body hair and a well developed tail tuft. The common names Golden babirusa and Hairy babirusa have been used lately for this species. The upper canines of males are short and slender and cross the lower canines in lateral view. The upper canines tend to diverge or be subparallel, but they may be weakly convergent. B. babyrussa is from the Sula Islands (east of central Sulawesi) and Buru (just south-east of the Sula Islands). Most workers think that the babirusas were introduced to these islands, and if this is so we don't know what their true place of origin was. Unfortunately babirusas from the adjacent eastern and south-eastern parts of Sulawesi remain unknown, so it is not possible to test whether or not they are particularly similar to B. babyrussa.
-- B. togeanensis Sody, 1949: the largest species, it has sparser, shorter body than B. babyrussa and, in contrast to B. celebensis, the tail tuft is well developed. The upper canines of males are this species' most distinctive feature: they are short, slender, rotated forwards and always converge. It is endemic to the Togian (or Togean) Islands, an island group that has been separated from the adjacent eastern arm of Sulawesi for c. 12,000 years. This suggests that the babirusas from the eastern arm of Sulawesi should be closest related to the Togian animals, but an absence of specimens makes this impossible to test (Meijaard & Groves 2002b). It cannot be ruled out that Togian babirusas were introduced to the Togian Islands by people. A male Togian babirusa is shown here.
-- B. celebensis Deninger, 1909: this is the babirusa we are all familiar with. It has sparse or absent body hair, a nearly hairless tail tuft, and long, relatively thick upper canines that emerge vertically, converge slightly and curl dorsally in a circle. B. celebensis is the commonest babirusa, the only one for which widely available photos are available, and the only species kept in captivity [it is claimed here and there that B. babyrussa is kept in captivity and that there are no B. celebensis specimens outside the US. I think this is incorrect and that people have wrongly assumed that many captive B. celebensis individuals represent B. babyrussa. Let me know if you know better]. B. celebensis is only definitely known from the northern arm of Sulawesi [map below from Meijaard & Groves 2002a].
On mainland Sulawesi, babirusas are certainly not restricted to the northern arm: historically they occurred across the island, and those of central Sulawesi at least are still extant. Unfortunately their specific status remains uncertain as not enough data is known - while populations might be continuous with B. celebensis and hence referable to that species, a skull from near Kulawi in central Sulawesi differs from other babirusas in being particularly small, in having proportionally long lower premolars, and in various cranial proportions. Meijaard & Groves (2002b) thought that the skull had its strongest affinities with Togian babirusas, and they concluded that it probably represented another taxon. More data is needed to confirm this. A babirusa skull photographed on sale in south-central Sulawesi has also proved enigmatic, being quite different from the Kulawi skull and unidentifiable based on the data available (Meijaard 2003).
Babirusas are also known from southern Sulawesi. Wiles & Mustari (2002) reported a skull, a tooth, and some eyewitness accounts of live animals from south-east Sulawesi, but in south-west Sulawesi babiruas are extinct so far as we know (though this needs confirmation). Hooijer (1950) named B. bolabatuensis (though originally as a subspecies of B. babyrussa) for teeth from the south-western arm of Sulawesi, though it has most recently been concluded that the material from this region cannot be reliably identified taxonomically (Meijaard & Groves 2002b). The Kulawi skull has at times been suggested to represent a modern example of B. bolabatuensis.
What with the taxonomically indeterminate babirusas of central Sulawesi, the unconfirmed extinction of those of southern Sulawesi, and the rumoured presence of babirusas on various small islands around Sulawesi, they are a ripe area for discovery and further research. Reports, photos and specimens are badly needed from these regions, and we have some way to go before babirusa diversity and biogeography is properly understood. And, of course, the phylogenetic hypotheses encapsulated in the 'new taxonomy' used here are not the last word on the subject and have arisen due to application of a phylogenetic species concept that some workers find objectionable. More on this matter soon - and, indeed, yet more on babirusas soon to come...
For previous babirusa articles see...
- The deer-pig, the Raksasa, the only living anthracothere... welcome to the world of babirusas
- Are anthracotheres alive and well and living on Sulawesi? No, but it was a nice idea. Babirusas, part II
- What's with the bizarre curving tusks? Babirusas, part III
- When babirusas fight (babirusas, part IV)
- This little piggy went ploughing (babirusas, part V)
For other Tet Zoo articles on artiodactyls see...
- McGowan's mystery bovid
- The legend of Hogzilla
- Welcome.... to the world of sheep
- Return.... to the world of sheep
- Tet Zoo picture of the day # 23 [on entelodonts]
- Deer oh deer, this joke gets worse every time I use it
- Duiker, rhymes with biker
- Sable antelopes and the miseducation of youth
- Giant killer pigs from hell
- The plasticity of deer
- Over 400 new mammal species have been named since 1993
- Great Asian cattle
- Stuffed megamammal week, day 1: Khama
- Stuffed megamammal week, day 2: Eland
- Stuffed megamammal week, day 3: Okapi
- Death by lightning for giraffes, elephants, sheep and cows
- Dromomerycids: discuss
Refs - -
Groves, C. P. 1980. Notes on the systematics of Babyrousa (Artiodactyla, Suidae). Zoologische Mededelingen 55, 29-46.
- . 2001. Mammals in Sulawesi: where did they come from and when, and what happened to them when they got there? In Metcalfe, I., Smith, J. M. B., Morwood, M. & Davidson, I. (eds) Faunal and Floral Migration and Evolution in SE Asia-Australia. A. A. Balkema Publishers (Lisse, The Netherlands), pp. 333-342.
Hooijer, D. A. 1950. Man and other mammals from Toalian sites in south-western Celebes. Verhandelingen der Koninklijke Nederlandsche Akademie van Wetenschappen, Afd. Natuurkunde Tweede sectie 46, 7-164.
Meijaard, E. 2003. Note on a photo of two babirusa skulls from Rante-pao, south-central Sulawesi. Asian Wild Pig News 3 (1),12.
- . & Groves, C. 2002a. Proposal for taxonomic changes within the genus Babyrousa. Asian Wild Pig News 2 (1), 9-10.
- . & Groves, C. 2002b. Upgrading three subspecies of babirusa (Babyrousa sp.) to full species level. Asian Wild Pig News 2 (2), 33-39.
Wiles, R. & Mustari, I. A. H. 2002. Records of babirusa and warty pigs in SE Sulawesi. Asian Wild Pig News 2 (2), 31-32.
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Uh, looks like a pig.
No really, I get it. But in the states, the tendency for escaped pigs to "devolve," complete with skull morphs in one generation -- it's no wonder this is a weird-out for many.
Hell, the whole "revert to the average" tendency was the reason for my dog bread choice: blue heeler -- a dingo influenced breed.
A very bad choice.
So few comments on THIS? Wow, i guess everyone is babirused out. Ha ha. Are we talking here about the phylogenetic species concept? Don't you mean diagnostic species concept? If those babi populations really have diagnostic features that allow them to be distinguished, are they species. What does the DNA say?
Why don't those mainland species appear to either share any ranges on the map or leave any gaps on the map between their ranges?
How much more babirusas? Let's have more icthyosaurs! More basal amphibians! Mpre obscure passerines and rodents! More transitional whales!
Gray: I believe that Tet Zoo is on hiatus and that Darren is only re-publishing material from version 1. And I think he's stringing it out as much as possible. Something to do with a major project that's taking up all of his writing time.
Colin Groves is a prominent proponent of the phylogenetic species concept (which I personally also support though more people are listening to Groves than are listening to me). He has also published significant revisions and divisions of other mammal "species" such as sika.
I'm an ichthyologist, so I have had little dealing with subspecies, other than elevating a couple to full species status. It strikes me that recognizing subspecies is harder than recognizing a new species. For the latter, "I ain't never seen one of them before!" might suffice. But with subspecies one need to know geographical range, intergrade zones, and have character differences which meet the 90% nonoverlap criterion. Some argue that recognizing subspecies should not be done, because subspecies are erected based on patterns of variation in some set of characters. This may obscure recognition of other patterns of variation seen in other characters. Anyway, you tetrapod people seem to have a lot of fun with subspecies.
Does anyone else keep pronouncing it "baribusa" in their head instead of "babirua?"
In the public gallery of the Raffles Museum of Biodiversity Research, there is a taxidermied babirusa, with a label stating that it's a golden babirusa (Babyrousa babyrussa). It is somewhat 'fuzzy' compared to the live B. celebensis I've seen at the Singapore Zoo.
Here's a photo. I have close-ups, but I need to go dig around for them, as they were taken in 2008.
http://www.flickr.com/photos/hai_ren/4357065304/
Darren:
Missing from your reference list.
Tom:
I'm not. To the contrary, thanks to Darren's recent posts, I'm finding myself reading up on babirusas, suid evolution, and the paleontology and the biogeography of Sulawesi. Highly interesting, though quite time-consuming.
Good question, but AFAIK, nobody has tried to resolve the babirusa species/subspecies complex by molecular methods yet. Plenty of work still to do on that subject.
Daniella:
More like *several* major projects, if I've understood him correctly.
Christopher:
He has also published taxonomic revisions of primates, and felids, and equids, and bovids, and marsupials, and echidnas, and... Groves is amazingly and impressively prolific.
Interesting to note that Buru, where B. babyrussa lives, is east of Weber's Line. If it is native here, and you take Weber's Line as the easternmost boundary of the Oriental region, then that means Australasia has a native pig.
James:
If you take Weber's Line as the boundary, then yes, but there is no real agreement on how exactly to define 'Australasia' biogeographically. Some even prefer to consider everything that is east of Wallace's Line* but west of Lydekker's Line** as a separate biogeographic region, Wallacea; in this case not only Sulawesi proper but Buru, too, would be outside of Australasia. There is much more that could be said on this matter, obviously; I hope to find the time to do so later.
* I.e., east of Borneo, Java, and Bali.
** I.e., west of New Guinea.
Darren
Given that we know that other large mammal taxa (Macaca, Anoa)on Sulawesi are polytypic (without committing myself as to whether the various taxa are species or subspecies) it seems highly likely that Babyrousa will be also. However, the actual published evidence that this is so is meagre to say the least: a couple of skulls, a bit of hearsay, and a dodgy photo or two don't make much of a case. Additionally most of the publications are in the 'grey' literaturs (Asian Wild Pig News, for heaven's sake!) so one wonders how much good peer-review has taken place. This is a problem that is growing, particulary in primatology where enormous taxonomic changes are proposed on little evidence other than a few smears of DNA and rapidly then published in Pet Welfare News, or some such ( I jest, but not much). The justification that is always given is that it is to make the 'species' known to science for conservation reasons and that taking a holotype and actually comparing it to other specimens and to existing published work is either too time-consuming or is inhumane. Excessive 'splitting' (the old-fashioned name for the Phylogenetic Species approach) can be confusing and unhelpful, but so can excessive lumping (the resurrection of the wonderful suid Sus cebifrons from synonymy just in time to prevent it's extinction being a case in point). My point really is to ask for balance and breadth in new taxonomic work and I would draw reader's attention to the description of the new warbler, Phylloscopus calciatilis, in the most recent issue of Ibis which I thought was a model of a how a new species description in a difficult and confusing genus should be handled. Mammalogists should read and learn from it!
I won't defend any species concept, but "splitting" and "Phylogenetic Species Concept" aren't the same. Splitting can be done under morphological concepts just fine -- "if I can tell them apart, they're different genera, and if I can't, they're different species" --, while, in theory anyway, applying the PSC where it hadn't been previously can lead to lumping (when more gene flow is detected than had been assumed) as easily as to splitting.
Not many people seem aware of the proposal that Colin Groves put forward to separate the Indonesian tigers from the mainland tigers, something like what we have now in clouded leopards Neofelis.
In 2006, Colin Groves and Ji H. Mazák used craniometric analysis to argue that the Indonesian tiger subspecies of tiger were in fact sufficiently different to be considered separate species. Hence the Sumatran became Panthera sumatrae, and the Javan and Balinese were P. sondaica, with the Balinese forming the subspecies P. sondaica balica.
But these findings were not adopted, nor were they supported by further research, as shown in this older Tet Zoo post:
I've been reading a lot of the papers posted on Colin Groves' website, and am very excited by many of his taxonomic changes, such as that done with mousedeer (Tragulidae) and pigs. I have been wondering if his reclassification of Asian deer has found widespread support.
Simon:
By any useful definition of 'species', the Sulawesi macaques are not just one polytypic species, but several. In fact, molecular data suggest that they may not even form a monophyletic clade but rather represent two separate dispersal events to Sulawesi (Evans et al. 1999). As for the anoas, they are almost certainly also (at least) two different species, although there has previously been some doubt about that. Incidentally, we know surprisingly little about the original distribution of lowland and mountain anoas on Sulawesi, and to what, if any, degree they are ecologically sympatric (see Burton et al. 2005, and references therein).
Er, have you actually looked at the sample sizes in Groves (1980) and Meijaard & Groves (2002)? I'd say that they've studied more than just 'a couple' of skulls.
Well, Zoologische Mededelingen, at least, is, AFAIK, a perfectly respectable journal. Do note that it is Groves' 1980 publication in that journal that laid down the basis for the later taxonomic 'upgrade' from subspecies to species in babirusas.
Regarding your general point about excessive/unjustified splitting; Colin Groves, as others have said, is a supporter of the phylogenetic species concept, and his
currently-held taxonomical "philosophy", if I've understood it correctly, is that at this level of classification, taxa are either full species or nothing. In other words, subspecies should not be recognised. Basically, what he's done to his babirusa subspecies of 1980 was to elevate them to full species in 2002. He's only being logically consistent in applying his preferred taxonomical principles. You may, of course, disagree with those principles, but to imply that he's somehow manipulating biological reality for conservation (or whatever) reasons isn't fair.
(By the way, are you Simon Tonge of Jersey Zoo? Didn't you once use to have babirusas there? If so, of what subspecies/species were they? Or was that kind of information unavailable?)
Having said that, I do agree with your call for balance and breadth in new taxonomic work and I must say that I'm a little uncomfortable with purely morphology-based taxonomy revisions nowadays. In this day and age, molecular supporting data should be included as a matter of course when studying the interrelationships of extant organisms.
Historically speaking, ornithologists have hardly been paragons of taxonomical rigour either. David, how many endemic bird species are there in Mexico again?
David:
Actually, that's the paleontological version. In neontology, it's 'if I can tell them apart, they're different species, and if I can't, they're different subspecies'.
References:
Burton, J.A., Hedges, S. & Mustari, A.H. 2005. The taxonomic status, distribution and conservation of the lowland anoa Bubalus depressicornis and mountain anoa Bubalus quarlesi. Mammal Review 35, 25-50.
Evans, B.J., Morales, J.C., Supriatna, J. & Melnick, D.J. 1999. Origin of the Sulawesi macaques (Cercopithecidae: Macaca) as suggested by mitochondrial DNA phylogeny. Biological Journal of the Linnean Society 66, 539-560.
Groves, C.P. 1980. Notes on the systematics of Babyrousa (Artiodactyla, Suidae). Zoologische Mededelingen 55, 29-46.
Meijaard, E. & Groves, C.P. 2002. Upgrading three subspecies of babirusa (Babyrousa sp.) to full species level. Asian Wild Pig News 2 (2), 33-39.
I'm loving these posts. The babirusa has been one of my favourite animals since I read about it when I was six or seven in a Ladybird book about exotic animals, which had a full page of text and a great painting. I vividly recall mentioning it in a story I wrote at primary school and being reprimanded by the teacher for making up this animal.
Last year I finally saw a live babirusa at Twycross Zoo and got tremendously excited. Not that it was doing much, but still, that was a lifetime ambition achieved.
From 101 to 249, depending on the species concept. I don't think it's a matter of how rigorously any of those concepts was applied⦠the numbers were presented to me as an illustration of how different species concepts name completely different entities and don't actually have anything in common other than the word "species".
Good observation.
Thanks to David and Dartian for their helpful comments, I am reminded of the old adage that one acts in haste and repents at leisure!
David, I'm well aware that the Phylogenetic Species concept and 'excessive splitting' are not the same thing, but they often seem that way to those of us who are not professional taxonomists but have to work with the consequences of their decisions. I work in zoos (well spotted, Dartian!) and managing conservation breeding programmes can be difficult when we can't be sure of the names or identities of the taxa we're working with, and just when we think we've got it sorted they change again. Incidentally, what happens if we apply the PSC to human beings? Are those who advocate its use really suggesting that there is more than one species of human on the planet? I think that problem alone undermines the concept.
Incidentally, getting back to babirusas, the European population now numbers less than 40 animals and is descended from only 5 founders brouught in from Surabaya Zoo in, I think, the 1970s. Because they are so inbred the breeding rate has dropped and unless new blood can be brought into Europe (currently not possible on Veterinary grounds) the species will be lost from our zoos. In the US the population is over 50 animals and breeding fairly well. I believe that all US and European animals are celebensis.
Nothing, we're way too panmictic. Several hundred years ago, there might have been 3 phylogenetic species (Easter Islanders, aboriginal Tasmanians, everyone else), but even that is over, and it would require that you're OK with a very short time of existence as a separate clade.
I've got a comment in the moderation queue for having posted 2 links, but in any case, I wonder if the reclassification of deer by Colin Groves has been widely accepted. I'm particularly intrigued by the splitting of sika into 4 species, the 3 subspecies of Eld's deer being elevated to full species, the heavy splitting of red deer/wapiti into multiple species (red deer, wapiti, and a jumble of Central Asian forms), possible hybrid origin of Pere David's deer, and hog deer and Javan rusa being sister species.
Also, Colin Groves proposed that the tigers of the Indonesian islands (Sumatra, Java, Bali) be split off from those of mainland Asia. According to this scheme, there would be 3 species of tiger: the tiger of mainland Asia, the Sumatran tiger, and the Javan tiger (with the Balinese tiger as a subspecies).
Apparently, this was not supported by the more recent research that determined that Siberian tigers were genetically very similar to Caspian tigers.
Is that a misprint? Because surely that would support the recognition of mainland tigers as a single species while saying absolutely nothing either way about the status of the insular taxa.
Not a misprint. As stated in an old post from Tet Zoo ('Revising' the Siberian tiger), Darren wrote:
This is the paper in question.
According to the tree constructed, the South China tiger (amoyensis) was the first to diverge, followed by Sumatran (sumatrae), Bengal (tigris), Malayan (jacksoni), Indochinese (corbetti) and the Caspian (virgata) and Siberian (altaica). So the Sumatran is actually nested amongst the extant mainland subspecies, and even if we follow the PSC, cannot be considered a separate species unless we consider each subspecies a species in its own right. If correct, this does carry a lot of implications on how tigers dispersed throughout Asia, and involved plenty of movements back and forth, and possibly localised extinction and replacement of certain populations with immigrant tigers.
Getting back to babirusa...
The animals in the Singapore Zoo and Night Safari collections are most probably B. celebensis as well, although the signboards haven't been updated yet and still state that they are B. babyrussa.
Where was B. beruensis found, has it been reliably dated, and has anyone tried to see if it might be a 5th species, or a chronosubspecies of any of the other 4 species?
It's now up (number 15). You can post up to 4 links (at least on Pharyngula), so I don't know what triggered moderation.
As Darren pointed out here (and see also my experiments that follow), there is no consistency in how many links will trigger moderation.
However, I believe my discovery is applicable: If you post a comment to another Sb entry with an absolute URL, but leave off the http://scienceblogs.com, like this:
<a href="/tetrapodzoology/2009/02/siberian_tiger_revision_2009.php">this older Tet Zoo post</a>
(rendered as: (this older Tet Zoo post))
it will not count against the link limit -- the URL counter appears to count the number of instances of http:// rather than the number of links. Don't ask me why Sb appears to be prejudiced against URLs pointing to scienceblogs.com when the http://scienceblogs.com is included, but (apparently) likes tinyurl links just fine.
Also, I am pretty sure that the URL entered with one's name and e-mail address when commenting counts against the total, so there are three links in #15.
For example, here's the links to all of the current babirusa postings, using my method described in the previous comment:
I am very unhappy with both PSC and oversplitting of mammals.
The result is "species" which are very similar, and confusion about identification, ranges, eventual hybrid zones and status in particular national parks. This happened to red deer, musk deer, gorals, baboons, vervet monkeys, hares, African elephants... don't even talk about rodents.
Splitting for conservation is notorious.
Interestingly, experts in African elephants currently made U-turn from Loxodonta africana/cyclotis split. Reasons are confusion about the status and how to treat hybrid populations. Not surprisingly, as in Queen Elisabeth in Uganda you see typical savannah elephants next to groups of visually forest elephants, with small size, round ears, straight tusks and no tusks in many adult females.
Jerzy:
Many forms of species concept have been tried and will be tried in this world of sin and woe. No one pretends that the Phylogenetic Species Concept is perfect or all-wise. Indeed, it has been said that the Phylogenetic Species Concept is the worst form of species concept except all those other forms that have been tried from time to time. (With apologies to Winston Churchill.)
Seriously speaking, if you don't like the PSC, then what species concept would you propose we should use instead? It would seem (to me, anyway), that the PSC is the closest thing to an objective definition of 'species' that has thus far been offered. Really, if there is a better alternative, what would that be?
Tangentially related: As Colin Groves has been mentioned quite a few times during this discussion, it should be pointed out that he is not a dogmatist when it comes to applying the PSC. Taxa above the species level should be monophyletic, yes, but
Thus, he is saying - in so many words - that in the real world, taxonomic pragmatism is sometimes unavoidable. On this I wholeheartedly agree. My personal favourite example of a case where I think that a strict PSC should not be applied is the polar bear. If one recognises the polar bear as a separate species, then the brown/grizzly bear Ursus arctos becomes a paraphyletic taxon.* Now, a strict PSC supporter would either have to lump the polar bear with the brown bear in the same species, or else recognise a whole plethora of separate species of the brown bear. To my knowledge, however, nobody seems to be seriously arguing for doing either of these things (or if someone is, he/she doesn't seem to be getting any widespread support). Everybody seems happy to accept the polar bear as a de facto "real" species.
* I'm presuming that this is common knowledge to regular readers of this blog, but to reiterate: It has been apparent for the last 20 years or so that the polar bear has evolved from the brown bear, and fairly recently too. The jury is still out on exactly how recently this has happened, but 250,000 to 200,000 years ago would seem to be a fairly conservative ballpark estimate; it is quite possible that the polar bear lineage separated even more recently than that. There is robust genetic support for this view, and it is not at odds with morphological or paleontological data either; to the contrary, it was the paleontologists Erich Thenius and Björn Kurtén who first proposed (in the 1950ies and 1960ies, respectively) that the polar bear has evolved from the brown bear.
To sum up: Any biological classification scheme devised by us humans will at some point end up demonstrating the validity of Orgel's Second Rule - that evolution is cleverer than we are. The PSC is no exception to that. But, by and large, it does seem to be as a good an attempt of an objective classification scheme as has ever been offered. Frankly, I'd say that by now, the onus is on the PSC's opponents to offer something better in its place.
Reference:
Groves, C.P. 2004. The What, Why and How of primate taxonomy. International Journal of Primatology 25, 1105-1126.
(I also have a whole bunch of references related to polar bear evolution, but I won't list them here unless someone is interested.)
Hi Darren, Great article as always! Now for the question! Is there any evidence that any (sub)species of babirusa once existed on Java? The reason that I ask is that while digging away through some antiquarian zoological dubitanda, I've uncovered a few sparse details of a seemingly now-forgotten beastie that may, just may, have bearing upon the babirusa, but which was reported not from Sulawesi or its off-lying isles but from Java. So any info that you may have that links the babirusa to Java in some way would be greatly appreciated. Thanks very much. All the best, Karl
Hi Karl, thanks for the comment :) All babirusas, living and extinct, are unique to Sulawesi and the adjacent Sula and Togian/Togean islands (though whether they evolved in-situ or came in from elsewhere remains a good question*: numerous fossil babirusa remains are known from the Pleistocene and Holocene, all are from Sulawesi). They're also on Buru in the Muluku Islands. As you'll know (it's discussed above), it may be that babirusas are only present on these islands because people took them there from Sulawesi. However, authors during the 1800s and before provided Borneo, Sumatra, Amboina and other places as home to babirusas - this is the best I can do as regards a possible association with Java, sorry.
* They certainly arrived earlier than other large Sulawesi vertebrates, and were thought by van den Bergh et al. (2001) to have moved over-land from Sunda Shelf region during the Oligocene. Since then, other studies have indicated that babirusa divergence occurred in the Miocene, however.. so either babirusas didn't follow this route (the alternative is that they island-hopped), or subaerial connections lasted longer than thought.
Ref - -
van den Bergh, G. D., de Vos, J. & Sondaar, P. Y. 2001. The late Quaternary palaeogeography of mammal evolution in the Indonesian archipelago. Palaeogeography, Palaeoclimatology, Palaeoecology 171, 385-408.
Hi Darren, Thanks for this, I suspected as much, because the Javan reports date back to the late 1700s/early 1800s. Will do some more digging, though, and assimilate it all into a future article/chapter, as I've managed to uncover some antiquarian prints of said beastie too. Thanks again!