I've been thinking about this concept of Frank's about happy little related snake tribes living in perfect harmony for some time. My instinct was to hear Kum-Bi-A music and turn the concept off but as I've recently re-entered the locality debate I'm thinking of it a bit differently.



I think that it is quite plausible that were we see a single large populations there may in-fact be many smaller sub-populations. These would naturally be related but gene flow BETWEEN them would be restricted relative to what happens WITHIN the sub-population. The reason I see this as plausible is because there would be an suvival advantage to such groupings. Given a sudden and significant environmental change there would be a good chance that at least one of the sub-populations would have the behavior or metabolic whatever to survive as a viable population to perpetuate the species. If sub-populations didn't exist such a change might leave behind survivors but they could possibly be too widely dispersed to be viable from a population perspective.



This got me thinking further along the lines of what would happen to these populations during less significant environmental shifts. It stands to reason that ever changing environmental conditions would set up a continual state where individual sub-populations are either expanding or contracting. If this is true then the concept of locality-matched animals could also have a temporal (time) component to it.



Example: Lets say collector X goes to CA every couple of years. In 1999, a very wet year, he visits his favorite site and collects a female Zonata under a piece of rock shard. In 2004, the third year of a moderate drought, he returns and naturally checks the same rock shard, this time finding a male. Classic thinking would be that he now has a nice locality matched pair but are they?



Suppose there are two populations on that hillside. One endures drier condition better (they absorb moisture from food better than most populations) while the other SEEMS to need more consistent access to moisture (because they have a strong preference for prey that requires more moisture). As climate conditions change these populations would mutually expand and contract and the interface between their populations would move up and down the hillside. If collector X's rock shard is located within the range of this moving interface then there is a good chance that the population utilizing the rock in 2004 was not the same as the one using it in 1999! Same geographic location, same rock and same species but different time, different conditions and different populations!



This is of course hair splitting but it is an interesting perspective on what wild populations are or might be doing.
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Darwin Rocks!

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