Looking back at my previous replies to your post, I realized that I was more focused on the scientific evidence for a close relationship between Eurasian and American species of Elaphe than directly addressing your arguments. I did not address some of the points you brought up. So I will do so in this post:



You wrote:

I must say that I'm very pleased to see the North American "Elaphe" no longer lumped together with Eurasian species. It is very evident that North American "Elaphe" are more closely related to Lampropeltis, Pituophis, and other North American snakes, than they are to any of the Eurasians.



My response:

That is one view point for measuring relationship. You are arguing that American ratsnakes are closer to their cousins (Lampropeltis, Pituophis et al.) than to their uncles (Old World Elaphe such as Elaphe scalaris). Using the same guidelines you have proposed, one would be arguing that the chimpanzees are closer to Homo sapiens than it is to the gorilla. And indeed there are scientists who would agree with that view point. Other scientists, however, would argue that the chimpanzee and the gorilla are more closely related to each other than they are to Homo sapiens. They would classify gorilla and chimpanzee in the same family (Pongidae) and support the recognition of a different family (Hominidae) for Homo sapiens. They do that because most of the evolutionary changes occured in the lineages leading to Homo sapiens. The chimpanzee has changed little from its ancestor, and therefore it is classifiable in its ancestral family. The same is true of New World Elaphe. Species such as Elaphe obsoleta, E. vulpina and E. guttata have changed little from their Eurasian Elaphe "uncles." Species like Lampropeltis and Cemophora, who are cousins of American species of Elaphe, have undergone most of the evolutionary changes and they are therefore classified in several different genera. If a classification is to reflect evolutionary history, shouldn't new species that have changed a lot be classified in their own genus and those that have not changed much be retained in the old genus? It is for this reason that Darwinians are classifying E. obsoleta, E. guttata and E. vulpina in Elaphe. It is for the lack of evolutionary changes in the American species of Elaphe that I oppose resurrecting Pantherophis and the creation of the new genus Pseudelaphe for the American species previously placed in Elaphe. Why invent new names for old taxa that have not changed?



You wrote:

My basis for drawing this conclusion, is that we see numerous hybridizations between the North American genera, but we never see any of the (to my mind misnamed) North American Elaphe hybidizing with any of the Eurasians.



My response:

Hybridization experiments can be helpful in evaluating relationships but it is an imprecise one. For example, if A, B, and C can hybridize freely with each other, is A more closely related to B than it is to C? Or is B and C more closely related to each other than either of them is to A? We can never know unless we look elsewhere for additional evidence. A more precise measure of relationship is available in the form of molecular data. Molecular data has shown that Old World Elaphe is ancestral to New World Elaphe, and New World Elaphe is ancestral to Lampropeltis, Pituophis, Arizona et al. That brings us back to the question of how we are to determine closeness of relationship. Are the American species of Elaphe closer to the relatives of their ancestor in the Old World or are they closer to their descendants such as Lampropeltis et al.? Of course I believe that American species of Elaphe are closer to the Old World species of Elaphe because they have not changed much from their ancestral form since migrating to the New World from the Old. Other scientists may have a different opinion. They are entitled to it. I believe that my preferred classification is more consistent with evolution, and it is no wonder that the sort of classification that retains American species of Elaphe in the same genus as Eurasian species of Elaphe is called "evolutionary taxonomy" or "Darwinian taxonomy." One of the alternatives to evolutionary taxonomy is Utiger et al.'s classification, which is in my view chaotic and not useful. Utiger et al.'s classification does not take into account evolutionary changes. Hence they have resurrected or erected nearly a dozen genera for the species of Elaphe that have not changed much since the Miocene. New names for taxa that do not change? There are many who may prefer that sort of classification but I do not.

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