New Article about Tylototriton shanjing taxonomy based on mitochondrial DNA

[John]

Thanks for that Jen, Yong Zhao and Alejandro. I've read it and I've a few thoughts. Their distribution map is completely lacking a scale. After some searching for a map of Yunnan with a scale (you can have a map, but no scale, apparently), I found this:

http://encarta.msn.com/map_701517816/yunnan.html

Firstly, the area they sampled from is about 400x300 miles at its longest dimensions. That's not that large an area and from these studies it would appear to me that the "verrucosus/shanjing" animals in this area are still in the process of speciation. How about catching a few specimens from Nepal or even India? And while we're at it, how about some photographs? As hobbyists, many of us have seen variations in verrucosus, some much more like shanjing than others. Would it be so much to ask to see what's being compared to shanjing?

I welcome the article but it falls far short of convincing me that verrucosus and shanjing are the same species. Perhaps in that small study area they are but I still think the jury is well and truly out for the majority of the specimens known as verrucosus. I also think that the "6%" species difference quoted by the authors is a little too specific (no pun intended) - they cite 3 other Chinese papers but no other scientific literature for this figure. I'm not a professional biologist but I seem to recall reading western papers that say ~2% is sufficient to declare speciation (or even less?). Can someone help me out here?

So I remain skeptical.

 

[FrogEyes]

The paper is believable, except for one major deficiency: they only tested ONE sample of T. verrucosus (an animal from China). If this paper had included samples of verrucosus from other geographic regions (India, Burma, etc), then I would find it a lot more credible. As-is, I would say this is an interesting preliminary study, but I wouldn't yet discard the idea that there are two species or a complex of species/subspecies. But clearly, the color and prominence of the "orange spots" is not enough to say that two animals of this complex are separate species.

I'm surprised that in two years, no-one has pointed out a significant deficiency in this argument. The validity of the names T.shanjing and T.verrucosus is inextricably tied to the type specimens. Regardless of how many species are involved in the complex, the type locality of both species is in western Yunnan. To determine which of the names is valid requires comparison of specimens *only* from the type localities. No other localities are required. Additional localities only help to determine species boundaries, not validity of the names. At best, this paper would only force "T.shanjing" to revert to "T.verrucosus", while all other populations would need new names

I too would prefer to see a more extensive treatment of the complex, though I think that would be quite the undertaking given the countries and regions involved. I have a sneaking suspicion that the Berkeley crew is working on it, and perhaps the Hanken lab as well.

It's been some time since I've looked at this paper. I had concerns about reliance on mtDNA, which is great for identifying long-distinct populations, but not so great at demonstrating conspecificity. I should note that significant variation was noted in the original descriptions of both T.shanjing and T.kweichowensis, possibly indicative of cryptic species. This study appears to actually be largely in agreement with the study which produced the description of T.shanjing! Regardless, I don't see introgression ruled out, since very few populations of T.verrucosus sensu Nussbaum et al exist in China and none from outside of China were included. There is also only a single, maternally-inherited trait examined, which hardly speaks of robust support for the conclusions. Due to lack of significant support, the conclusions are premature.