Reptile & Amphibian Forums

(great pics Pierson)
Here's a rough little baby erythrogaster from north central Missouri. Blotched are either unicolor bronze or blotched here. Interesting that both subspecies live together.

I can't see enough erythrogaster. Keep em coming! I'd love to see some adults as well. When you say the two ssp. are living together, are you implying that both ssp. occur sympatricly or that there is just a lot of variety in the resident population? I've never heard of the former scenario actually occurring.

-Pierson
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Pierson Hill

Herpetology and Herpetoculture

Pierson,
The two subspecies live together. I have a poor (really poor) picture of a blotched adult I'll put up in a second. I'll be back there to get decent pictures this fall.

Joe

Two subspecies living sympatrically and remaining genetically seperate is, by definition, impossible. The two different forms would then be different species if there were some sort of reproducitve barrier. What I think you're witnessing is just extreme phenotypic variability, perhaps because you reside in the are of intergradation between N. e. flavigaster and N. e. transversa. I bet that if you took any given litter of babies from a single female in your area, some would grow up to be unicolor and some would retain blotching into adulthood. You'd also see everything in between. Does anything you have witnessed from your area of Missouri suggest otherwise? For instance, are unicolored watersnakes found in slightly different areas or habitats than the blotched specimens?
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Pierson Hill

Herpetology and Herpetoculture

Thats interesting. If the two variations show up in the same litter then would they still be sub-species? Or reduced to variation among the single species?

I'll check into collection laws in Missouri (outside the NWR) and consider attempting to collect a female prior to giving birth later this year.
Anyone know the laws off hand?

Joe

Sorry, these are the only laws I'm familiar with that apply to your area. It's the last one I'm having trouble with though.
However, this species/sub sp./integration theory is really getting to the nuts and bolts of herp field study. Keep it up guys, there can always be a surprise under the next rock!
Michael

I suspect the reason you are seeing such variation is that you lie within the intergradation zone between the two subspecies. Typically, when the ranges of subspecies of snakes overlap, the snakes found within this area can resemble either subspecies or be intermediate in appearance. As you move into the range where only a single ssp. occurs, you find far less variation and the snakes can be characterized and given a name. So you have transversa and flvigaster which are the same snake, just geograpical color variants. Is this making sense?

-Pierson
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Pierson Hill

Herpetology and Herpetoculture

So, hypothetically speaking I have: species X, red to the east and yellow to the west; therefore subspecies Xred and subspecies Xyellow. On line north/south geographically central to each, I simply have species X, red/yellow which is orange.

Therefore from east to west:

Species X (sub-species red) to species X (red yellow)= [integrade orange] to species X (sub-species yellow).

Does this make an Xorange (an intergrade) a "super sub-species"?

... male yellowbelly with female redbelly = offspring??
Would this, could this occur naturally?
Michael

It ususally doesn't operate so cleanly as that. In your area of intergradation, you're going to get the gamut of phenotypes. You could find reds, yellows, and varying shades of orange all in the same area. The percentage of a given phenotype varies going east and west until you get all pure reds or all pure yellows. For example, I found what looked like an erythrogaster erythrogaster in the extreme eastern portion of flavigaster range in Alabama. Snakes caught by others from the same area mostly resembled flavigaster and heavily flavigaster influenced intermediates. I just happened upon an animal that received some "redbelly" genes from its parents, who probably looked like yellowbellies. It's confusing, I must admit.
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Pierson Hill

Herpetology and Herpetoculture

I hear you. I was using the "line/point" as an example (as I know you know) instead of an X/Y axis graph because I tend to be a mathematical moron. The shades of grey between east/west or (-x to x) are what's confusing me. As I sent the last post I realized that I had'nt asked the question that concerned me, namely - is there a "firm" or absolute identifying factor to discriminate a species from sub-species - or even better -
what is the difference between a redbelly and a yellowbelly?
Michael

I think the confusing thing here is that there really is no integrade. There are blotched right next to a form of the yellow belly. Even this yellow belly form is a bit unusual because its dorsal coloration is bronze.

If you look at milksnakes from east to west across Iowa (for example) you get a gradation from brown to red, in general. But also a few brownish snakes in the west, or a few reddish snakes in the east. Whats odd here is 2 clearly distinguished subspecies right next to each other. One blotched and one uniform.

Its possible that this species once ranged right across northern Missouri and blended into the eastern erythrogaster populations. But now this (at Swan Lake NWR) population is isolated yellow belly amidst the western blotched population. It makes one wonder about the evolutionary purpose of blotches vs uniform dorsal coloration.

Joe

If the dorsal coloration of the snakes you are seeing is bronze, then that suggests that those snakes are more closely related to transversa. Blotched Watersnakes can be blotchless and are so with regularity throughout thier range, even amidst their blotched siblings. The tell-tail sign is if the venter is a tan/cream (as opposed to yellow) and has encroachment of dark pigemnt on the sides. I'd love to see some pics of adults.
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Pierson Hill

Herpetology and Herpetoculture

If the belly is tan/cream (not yellow) and there is dark pigment encroaching or across the scute edges the snake is_____________ .

The snake is very dark, virtually black with distinct but very difficult to see blotches and the belly is cream/vanilla with dark "smoke" across the scute edges. Snake is at least 3 ft long.
(Same snake as before - Schiz - that I've been calling
E.transversa)

Michael

I'd have to say you've got a transversa based on ventral coloration but the reality of it is that you could just as easily have a snake from the Blotched/Yellowbelly intergrade area and it could have mixed blood. Sometimes when phenotypic characteristics fail, you have to rely on locality data, which I am aware you don't have. Frustrating, huh?
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Pierson Hill

Herpetology and Herpetoculture

It certainly is! Part of the pride of rearing these guys is knowing exactly what they are and passing that info on intelligently especially to those casual guests that are simply curious, just being initiated.
The very idea of saying "yes, these are all nerodia, this one is taxispilota. There, pictiventris and that one ... we don't talk about that one! Yeah okay, fine! It's a snake. It eats fish! Get out of my house!" could give me a complex.

Oh joy ... so much to learn. There really is a new adventure behind every rock and under every board and sheet of tin.
Michael

The difference between Redbellies and Yellowbellies is only coloration and general geographic distribution. Heck, they are the exact same species. Yes, there is a large and confusing area of intergradation where these distinctions fail but you will NOT find a Louisiana Redbelly or a South Carolina Yellowbelly. The fact that the ssp. of this species are recognized is due to the fact that the identifying characteristics of a ssp. hold up 99% of the time when you are within that ssp. range. When you get into an intergradation zone, forget it: anything goes.
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Pierson Hill

Herpetology and Herpetoculture

OK, this is cool. Now, do I have a yellow belly or not damit! Please, please read post response above. I need help. Are you a doctor yet? Forget that, doctors practice medicine, you can practice on me. How are you at herp labotomies? I had a question, now I have twomore in my head!

Pierson, I know you said "anything goes", and I'll bet you're fun at parties however ... is an erythrogaster an erythrogaster; period? I know I was referencing reds and yellows only earlier, but does this apply across the board of all "Es".
Michael

Alright, I spent some time since the last post considering my question and I realize that I do indeed have a yellowbelly. In fact I'm a lily-livered, bushwhacking back-stabber as well but this still does'nt tell me what kind of snake I have!!!!!
Michael