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Emdoidea blandingi (underlined) the Blanding's turtle and Glyptemys ( Clemmys) insculpta (underlined), the North American wood turtle. These two species have repeatly breed and produced hybrids - with interesting combined features. Harding and Davis (1999) wrote a paper on these hybrids and Harding has taken photes (2003) of many hybrid individuals with interesting traits form both Genus species. The standard criteria for a viable species is the inability to breed and produce a viable offspring capable of reproduction. If two different species produce living young, the best to expect is a sterile 'mule'. Thus, if E. blandingii and G. insculpta are producing hardy hybrids ( As far as known no reproduction of the hybrids is known - and if so, would totally throw scientific turtle classifcation on it's ear!) Then, at best, according to the Linnanean scientific classification standard, the two above species of turtle should be then reclassified as separate species within the same genus (probably Glyptemys - thus, the blanding's turtle may become Glyptemys blandingii {underlined}).

Pilirin
9/28/07

ADDENDUM:

On E blandingii being moved to Glyptemys: It would be more likely since Emdoidea is a monotypic genus.

I think you mean "Emydoidea", and I think you're laboring under a particularly naive interpretation of Mayr's Biological Species Concept. Not having the Herpetological Review articles you reference handy (in part because Herp. Review lags in the dark ages without an online version) I don't know the details of the situation, however.

Patrick

My apologies for the Typo. Yes, that is what I meant. Thanks for writing. Haste makes waste.

A general search can put you on track with additional info for you.

I hesitate to list sites as it may be in violation of Kingsnake terms.

repeatedly

from

Well, I found a few websites that briefly mention the relevant Herp. Review papers, but none that provide enough detail for me to figure out exactly what's going on. Too bad about all the restrictions on what you can post here. Sure can kill discussion.

Patrick

Hello Patrick,

Yes, it can be chafing concerning restrictions. I'm glad you found the information. It will be interesting to see with additional DNA research on these two species, on what will turn up.

Thanks for writing.

Erin

Hi,

It's important to realize that most current taxonomic work is done in a cladistic framework, and using the evolutionary species concept, meaning that evolutionary history and genetic distinctness is more important than biological interactions. There's a lot of argument among scientists over whether or not this is a good thing, but it's the way most papers are written these days. Hybridization in captivity is generally not taken as evidence that two species should be considered one; even frequent hybridization in nature (as in American, southern, and Fowler's toads, or the five-lined skink group) is not sufficient if the species involved maintain their distinctness in nature.

It's been a while since I read any of the Emydidine classification revisions, but as I recall the reason Clemmys was broken up into Clemmys, Actinemys, and Glyptemys was because Terrapene arose from within Clemmys according to the researcher's cladogram, thus rendering Clemmys (in the older, more inclusive sense) paraphyletic. There were two possible nomenclatural revisions: 1) include the bog, wood, western pond, and spotted turtles together with the box turtles in one big genus, or 2) split Clemmys up. The researchers went with the latter option, probably because they wanted to leave the well-defined genus Terrapene alone.

Now, as for Emydoidea, I don't believe any one has suggested it should be included with any of the former Clemmys species; it is usually shown as being a basal sister lineage of the Clemmys-Terrapene lineage. In some reconstructions it is shown as the sister species of Emys orbicularis, the European Pond Turtle, so it could be moved to that genus, rendering it Emys blandingi.

I hope this was helpful.

ALong with the hybrids in captivity, this really means little. Most species become species due to reproductive isolation. However, this isolation may be in the form of behavioral or geographic, which are often null in captivity.

>>Hi,
>>
>>It's important to realize that most current taxonomic work is done in a cladistic framework, and using the evolutionary species concept, meaning that evolutionary history and genetic distinctness is more important than biological interactions. There's a lot of argument among scientists over whether or not this is a good thing, but it's the way most papers are written these days.

Yes it is unfortunate. Most biologists still accept the biological species concept, and yet a large number of the young taxonomists (the upstarts) are using the evolutionary species concept. That creates controversy and endless arguments whenever someone proposes a new species on the basis of the evolutionary species concept.

>>Hybridization in captivity is generally not taken as evidence that two species should be considered one; even frequent hybridization in nature (as in American, southern, and Fowler's toads, or the five-lined skink group) is not sufficient if the species involved maintain their distinctness in nature.
>>
>>It's been a while since I read any of the Emydidine classification revisions, but as I recall the reason Clemmys was broken up into Clemmys, Actinemys, and Glyptemys was because Terrapene arose from within Clemmys according to the researcher's cladogram, thus rendering Clemmys (in the older, more inclusive sense) paraphyletic. There were two possible nomenclatural revisions: 1) include the bog, wood, western pond, and spotted turtles together with the box turtles in one big genus, or 2) split Clemmys up. The researchers went with the latter option, probably because they wanted to leave the well-defined genus Terrapene alone.

It is quite obvious from those cladograms that the North American emydidine turtles is a clade that evolved from a common ancestor which migrated from Eurasia. The genus Clemmys is a paraphyletic genus that is close to the base of this clade. Breaking up this genus is silly since the species in this genus form a rather homogeneous group morphologically. The cladists' intolerance of paraphyletic taxa rears its ugly head again. They should simply leave paraphyletic taxa alone, as taxonomists have done for centuries, instead of generating taxonomic chaos continuously.

>>Now, as for Emydoidea, I don't believe any one has suggested it should be included with any of the former Clemmys species; it is usually shown as being a basal sister lineage of the Clemmys-Terrapene lineage. In some reconstructions it is shown as the sister species of Emys orbicularis, the European Pond Turtle, so it could be moved to that genus, rendering it Emys blandingi.
>>
>>I hope this was helpful.

I hope that cladists would simply come clean and tell us up front why they are splitting taxa. Tell us that the new taxa is proposed because they are following Hennig's lead and that Hennig says paraphyletic taxa should be disqualified. What many of them are doing is simply dishonest. They claim that the taxa they split is "not monophyletic." That deliberate choice of terms is deceptive because to most biologists "not monophyletic" is synonymous polyphyletic. Since no biologist would knowingly recognize polyphyletic taxa, many biologists are thus deceived into accepting the new taxonomic proposals as valid. If the cladists would confess that they are proposing the new arrangement because the old taxon is paraphyletic, the new proposal would have been ignored by a large number of biologists, since many biologists, unlike the cladists, make no distinction between paraphyletic and monophyletic taxa and accept both as valid.

Hence, cladists should make clear, if they are honest, whether the taxa they propose to split is paraphyletic or polyphyletic, instead of deliberately lumping both types of taxa under the umbrella term "not monophyletic."

>>Emdoidea blandingi (underlined) the Blanding's turtle and Glyptemys ( Clemmys) insculpta (underlined), the North American wood turtle. These two species have repeatly breed and produced hybrids - with interesting combined features. Harding and Davis (1999) wrote a paper on these hybrids and Harding has taken photes (2003) of many hybrid individuals with interesting traits form both Genus species. The standard criteria for a viable species is the inability to breed and produce a viable offspring capable of reproduction. If two different species produce living young, the best to expect is a sterile 'mule'. Thus, if E. blandingii and G. insculpta are producing hardy hybrids ( As far as known no reproduction of the hybrids is known - and if so, would totally throw scientific turtle classifcation on it's ear!) Then, at best, according to the Linnanean scientific classification standard, the two above species of turtle should be then reclassified as separate species within the same genus (probably Glyptemys - thus, the blanding's turtle may become Glyptemys blandingii {underlined}).
>>
>>Pilirin
>>9/28/07

Things are a bit more complicated than that. First of all, any human classification is merely an attempt to describe nature. Nature needs not and often does not obey any human definitions. A well known example is the wave-particle dichotomy. Humans define waves and particles as separate entities. Yet nature shows us that all particles exhibit wave characteristics, including big particles the size of humans and even the earth itself, and waves exhibit particle characteristics.

The classic definition of the biological species concept is an attempt to describe nature. In nature, organisms do not interbreed freely. Each "kind" of organism attempts to interbreed only with its own kind. The question one may ask is why? A horse, for example, is not forbidden to try to mate with, say, a cow by anyone. So, why would a horse and a cow avoid mating on a purely voluntary basis? The answer to what we see in nature is that each species appears to have evolved with its own unique set of features that will permit it to cope with its environment (finding food, avoiding predators etc.). If this set of features is permitted to be "polluted" or diluted by a different set of features (from another species which is adapted to a different way of life), then the organism with this mixed set of features from two different species may have lower fitness (i.e. lower rates of survival) and be unable to survive and reproduce. We see an example of this in nature. Hyla chrysoscelis and Hyla versicolor, the two gray treefrog species, produce infertile offspring because one species has twice as many chromosomes as the other. One is a so-called diploid, and the other is a tetraploid. Since the outcome of interspecific species is often disastrous, many species have evolved mating rituals to ensure that it is only going to be mating with its own species. Different species of turtles, for example, will only mate with individuals that are showing mating behavior that is unique to its own species.

Of course, accidents do happen in nature, and occasionally interspecific hybrids are produced. In general, these hybrids often are much less fit because their phenotypes are less adaptive to their environment. In some rare cases, however, hybrids may be more fit to a new environment than either parental species. The hybrids may then be able to survive and reproduce and become established as a new population or even a new species. As I said, nature does not obey any human definitions, so interspecific hybridization can and do occur. It does not mean that if two species hybridize, then they are the same species. It will depend on whether the hybrids are able to survive and reproduce, and on whether the two species will continue to mix freely. If they do, then they are the same species. If not the occasional hybrid will die out, and the two species will remain distinct and be recognized as distinct species.