Reptile & Amphibian Forums

i was thinking, how we group animals. u got ur genus then ur species then a subspecies. but is there any middle ground in there? like can there be a species with many different morphs and hybirds and different patterns, yet they are all simply the same species? i dont think we can group animals that easily. ill use s few examples. look at the eastern racer, with the subspeacies northern black racer and southern black racer. they are like the same thing. and look at an eastern milk snake and a pueblan milk snake. they are the smae species but look way different. so in other words a northern black racer is to a southern black racer as an eastern milk is to a pueblan milk. but there seems to be way closer of a connection to racer subspecies and milk snake sub species. so is separating and grouping animals really that simple and clear cut? like can there be a population thats 2/3rds one thing and 1/3rd another? or can u have a population evolve in such a way that it eventually becomes its own subspecies?

I don't think any systematist or taxonomist will tell you that taxonomy is a simple endeavor. As in every biological science there are gray areas, areas where even experts disagree. And when new evidence is discovered and new techniques evolve, as in every branch of science, the taxonomy is re-evaluated. Just compare the two "official" checklists for the the U.S.: Collins' CNAH list and the SSAR (Crother) list to see how committees of experts can disagree on U.S. species. And, add to that, the debate on the very concept of "species". Differing philosophical approaches yield different answers and interpretations of evidence.

Harold,
Dr. Rick Staub of Davis, Calif. is trying to get in touch with you. He has a post on the field observation forum.

Richard F. Hoyer

Nobody claimed it was simple. But it's not arbitrary.

First of all, most of what you're discussing isn't very important, or is completely irrelevant, to a biologist. Anything that happens in captivity is irrelevant, because biologist have no interest in classifying captive animals. Color and pattern variations are of very little importance. "Morphs" are of no importance at all.

Species are what is important to biologists. A species is an isolated gene pool. (Isolated in nature; they can possibly be crossed in captivity, but again, that's unimportant).

Subspecies are of much less importance. A subspecies is a population inhabiting a particular geographic area that displays some consistent traits, imply some level of _partial_ isolation from populations of the same species in other areas. Subspecies are populations that may be on their way to becoming full species.

>>i was thinking, how we group animals. u got ur genus then ur species then a subspecies. but is there any middle ground in there? like can there be a species with many different morphs and hybirds and different patterns, yet they are all simply the same species?

Those were some good responses already, but as a hobbyist and recreational herpetologist, I might have a little different view. I'll use the corn snake complex as my example, since I keep a few and have dabbled in this species for many years.

First, let me say that some folks see the corn snake group as being one, two, or even three different species. I look at the ratsnakes of this group as just one species, Pantherophis guttatus, with several different subspecies, but all closely related. Those thinking it's more than one species would be correct to use the term "hybrid" for crosses of their various species, but those thinking it's all one species would likely just call them "crosses", meaning they are like intergrades (only not natural).

In a more specific example, one of those crosses, a corn snake (amelanistic) x a Great Plains ratsnake, results in a morph called "creamsicle". Many consider this form to be a hybrid, and probably less of us consider it just a "cross" and a "morph". You can see how the terms hybrid, crosses, and morphs come into play.

Then, in answer, I can see how you think all these terms can be used within just one species. I believe they are all used within the "guttatus" species, but that the "hybrid" term is not valid in my scheme. There are also the color and pattern combinations that naturally vary amongst the subspecies. Some colors and patterns are unnatural, however, and are created by mixing genes and mutations, giving them a name, and continuing the line in the hobby. The term "morph" refers to a form that has one or more mutations at work, giving the snake a different color or pattern, etc.

i dont think we can group animals that easily. ill use s few examples. look at the eastern racer, with the subspeacies northern black racer and southern black racer. they are like the same thing. and look at an eastern milk snake and a pueblan milk snake. they are the smae species but look way different. so in other words a northern black racer is to a southern black racer as an eastern milk is to a pueblan milk. but there seems to be way closer of a connection to racer subspecies and milk snake sub species. so is separating and grouping animals really that simple and clear cut? like can there be a population thats 2/3rds one thing and 1/3rd another? or can u have a population evolve in such a way that it eventually becomes its own subspecies?

You're right, the racers are much more closely related, and much closer in their ranges, I might add. You could argue that no subspecies designation is needed here, but some folks have seen enough consistent variation to distinguish the two forms, but not enough to split the species. The whole idea of species and subspecies is pretty controversial, but I've always gone by the test for species that the forms have to be intergrading or are so closely related they can hardly be told apart. With the two black racers, they are obviously intergrading, and are the same species.

With the milksnakes it's not so clear. Milksnakes, Lampropeltis triangulum, have one of the largest ranges of any snake species in the world. Obviously they are going to have a lot of variation. In my opinion, the only reason the species hasn't been split into separate species is because each subspecies intergrades with at least one other subspecies, meaning there is an exchange of genes. The two ssps. you mentioned, Eastern milk and Pueblan milk, are widely separated, with many different ssps. inbetween, so they don't exchange many common genes, but they're still connected. If they weren't connected, they would probably be considered separate species, at least by the taxonomists I know.

Then you have situations like the Eastern milk coming into contact with the scarlet king, L. triangulum elapsoides, and not intergrading. These situations make us take hard looks at our definitions of what a species is. Because the scarlet king intergrades with other subspecies it comes into contact with it's still considered a milksnake by most.

Obviously you can have populations that evolve to become a separate subspecies, as you can have a subspecies eventually evolve into a separate species, as I think the scarlet king is in the process of doing.

Hope this helps...TC

No, it's not. Because of all the differences in opinion, many animals that one taxonomist believe should be given full species designation do not get that designation because other taxonomists disagree. As far as "morphs" go, the only ones the biologist would be interested in would be those naturally occurring variants (ex--F. pardalis, the panther chameleon, with the apparently locale-specific coloration); but morphs can interbreed and produce viable offspring, so they could be considered a species under the conventional definition. Hybrids, however, present a bit of a conundrum, as with many reptiles hybrid animals by conventional definition can produce viable offspring, making them at least eligible for species designation under the conventional definition. In the end, DNA profiling will most likely have the last say, at least when most everyone agrees what the correct DNA similarity percentage for a species is

>>i was thinking, how we group animals. u got ur genus then ur species then a subspecies. but is there any middle ground in there? like can there be a species with many different morphs and hybirds and different patterns, yet they are all simply the same species?

Yes. There are lots of different breeds of dogs and chickens but all breeds of dogs are the same species and all varieties of chickens are also the same species.

> i dont think we can group animals that easily. ill use s few examples.

As a matter of fact, it is not easy to classify animals. Plants are also difficult to classify, may be more so because many plants can freely hybridize with each other.

>look at the eastern racer, with the subspeacies northern black racer and southern black racer. they are like the same thing.

Looks are often deceiving. Many milk snakes look similar to mountain kingsnakes, but milk snakes and mountain kingsnakes are different species.

> and look at an eastern milk snake and a pueblan milk snake. they are the smae species but look way different.

Yes they do. The gray banded kingsnake is another good example of a variable species.

> so in other words a northern black racer is to a southern black racer as an eastern milk is to a pueblan milk. but there seems to be way closer of a connection to racer subspecies and milk snake sub species. so is separating and grouping animals really that simple and clear cut?

No, it is not. Even scientists often disagree as to what a species is. And they often disagree on whether two populations are the same species or different. Most biologists, however, agree that if two populations are reproductively isolated from one another, then they are not the same species.

>like can there be a population thats 2/3rds one thing and 1/3rd another? or can u have a population evolve in such a way that it eventually becomes its own subspecies?

All biological organisms have to be adapted to their local environments. Sometimes these adaptations will cause changes in morphology. For example, the Lampropeltis zonata herrerae living on a desert island has to adapt to this atypical habitat. One of the adaptations that herrerae has made is to have reduced red markings. L. z. herrerae is therefore often classified as a different subspecies because it simply looks different. To some biologists though, the mere fact that it looks different and the fact that it is stranded on an island means that it will be unable to share its genes with other populations of L. zonata. To these biologists, it is sufficient evidence that L. z. herrerae is a different species. Other biologists disagree because they do not consider geographic isolation a valid criterion for recognizing new speces, because otherwise populations of the same species on different sides of the same river would be classifiable as different species. They also point out that if one looks close enough, then one can find at least one difference between two populations on opposite sides of a geographic area. Therefore herrerae should not be recognized as a different species.

Disagreements like these are quite common nowadays, as different schools of taxonomists have embraced different definitions of species that are mutually incompatible. BTW, it is possible for different individuals of the same species living in the same area to evolve into a different species. Geographic isolation is not necessary. The Cichlid fishes found in some African great lakes are a good example. Biochemical data shows that many different species living in the same lake originally were descended from the same ancestral species. And yet competition among individuals of the same species is so intense that it provides a strong selective advantage to some of the individuals of the ancestral species to adapt to a different ecological niche (which in this case primarily involves different food sources). Therefore those who suggest that geographically isolated populations will inevitably evolve into different species are simply mistaken. Geographic isolation is not even necessary for speciation to occur. Hence geographic isolation should not be used as a criterion for naming new species.