sirtalis color patterns in midwest

[mfwestphal]

Have been enjoying thamnophis.com for a long time & finally have something to contribute!

Follow link below to our newpaper on T. sirtalis color patterns in Manitoba, South Dakota and Kansas. Had much help in this study from herpers & breeders. Plus had much fun rearing many hundreds of baby garter snakes. (& nearly went blind scoring color patterns on said baby snakes...)

Thanks to all,

Mike

PLoS ONE: Heritable Variation in Garter Snake Color Patterns in Postglacial Populations

P.S. Free download, woo woo!

[Stefan-A]

Neat.

[guidofatherof5]

And contribute you have.
Be sure to go to the "Welcome Lounge" and make an official introduction so we can give you a proper greeting.
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[Mommy2many]

Wow. "Neat" is an understatement. Nice work! Welcome to our forum!

[katach]

What fabulous information! Welcome and thank you for sharing.

[Jeff B]

Mike I just read you paper, boy am I glad I just finished taking a graduate level biostatistics class last spring or I wouldn't understand half of it, lol.
Hey, a couple of key things if you don't mind my review. First off, excellent work period.
I think some of the things sited in detail and much more analytically, agree with what we casually observe in captive populations with know similar locales to the study population locales in general.
I was a little confused when there was no diffence in blotch size means between sexes, but then it looked like you went on to explain there was an adjustment for size and proportion each individual examined, which would make perfect sence, did I interpret that correctly?

You probably have already considered this but with regard to this reference:

Additionally, prior molecular studies (allozyme and mitochondrial) have documented the expected low genetic diversity in northern populations of T. sirtalis [31], [38], [47], [48], e.g. that all Manitoba populations have only a single mitochondrial haplotype at the cytochrome b locus [47].

This above while significant still has limited power, as it is a small fraction of genome. You also may or may not be aware that whole genome comparision is on the very near horizon, due to new Ion Torrent technology. If you are not aware of the Ion Torrent, check it out, it's pretty exciting for sequencing. In my line of work it may even soon be used for infectious disease diagnostics and typing.


I think this part below was very well thought out and addressed at the end of your results:

A common issue in the comparison of genetic variance estimates among populations using a quantitative genetic design is achieving statistical precision that allows the genetic variance and heritability to be bounded away from zero, and also allows those parameters to be bounded away from the population to which it is being compared [49]. Our design is robust in that we have multiple litters with hundreds of individuals from each population, thus for most of the within-population genetic estimates the 95% confidence intervals are easily bounded away from zero. However, we are unable to bound the estimates from each population away from one another based on their 95% confidence intervals (Table 1). Although within-population significance testing of quantitative genetic parameters is feasible in wild populations, comparing the same parameters among populations is difficult given the extremely large numbers of litters required [50], [51]. The fact that our estimates overlap could therefore be a consequence of a lack of statistical power, or could reflect areal-world equivalence between the populations. That said, given the robustness of the within-population estimates, our data still strongly contradicts a reduction in genetic variance in the recently colonized Manitoba population relative to the South Dakota population (Fig. 2 and

Also I was thinking the exact same thing as I was reading your discussion before I read this below:

That is, southern populations express significantly larger mean dorsolateral blotch area compared to populations to the north (i.e., Kansas blotch area>South Dakota blotch area>Manitoba blotch area; Fig. 1). Furthermore, this pattern is robust regardless of age (i.e., neonate or adult), which is consistent with the single population ontogenetic effects demonstrated by [46]. Although our data do not allow us to directly identify the mechanism driving this latitudinal pattern, a likely candidate variable is the difference in the thermal regimes experienced by southern to northern populations. Dorsolateral blotches are thought to function in both thermoregulation and predator startle response behavior [29], [36]. Reduction in blotch area results in a concomitant increase in the area of the integument covered by melanophores, and would be expected to increase thermoregulatory efficiency [36], an important adaptive trait in an ectotherm living in the extreme north. Because reduction in blotch area might be maladaptive with regards to predation, and because high expression of red pigment might be maladaptive with respect to thermoregulation, an evolutionary tradeoff may be playing a role in the maintenance of standing variation in pigmentation. The extent to which dorsolateral blotching mediates an evolutionary tradeoff between predator avoidance and thermoregulation deserves further study

One final thought you may already have considered, but have you considered human population density or even human travel thru a study population area over time, or human variable in general between populations studied as a negative variable factor on genetic diversity and what effect that may contribute? ie simply put and generally; increased human activity= decrease in diversity

Anyway great work and very fascinating stuff, but I know what you meant and have been through when you spoke of going cross-eyed from the day to day grind of research, been there done that, still doing some, but now you get to kick back for a bit and say ahhh it was worth it Keep up the great work

[mfwestphal]

Hey Jeff, thanks for the great comments. Will try to answer all your questions!

1. Yes, I adjusted blotch size for overall snake size & it was a wash for sex.

2. We're all stoked about whole genome comparisons, I'm esp. interested in the ease with which we will be able to get at the genes that actually control the color traits I write about.

3. Your remark about possible anthropogenic effects is intriguing. The Interlake seems to be experiencing a shift to aspen parkland due to fire suppression etc. Might be something worth looking at.

I appreciate the thorough read! Let me know if you have any other questions.

Mike

[PINJOHN]

have made a valiant effort to absorb it all, with i am afraid to say a very very limited success, i have to admit most of it is beyond my intellectual capacity, but it is heartwarming to know some one is working away to increase the overall knowledge of garter snakes and the challenges they face in the years to come.
i really regret not paying more attention in class all those years ago,

[snakehill]

Yeah! Me too! (what PINJOHN said!!!)