Sunday, June 18, 2006

the wind, the water, the wicker, the work

Seán's girlfriend Krista's house is where I stayed last week watching the beasts. She lives on a bit of a mountain with a great view of the Plott Balsam Mountains. Here is one such view, click it for bigger:

Now with that out of the way, I can recount my bear story, briefly. I was up fishing on Moses Creek (in the Caney Fork watershed, number 16 on the map below) and it was about 9pm. I wasn't too far up, maybe 1 mile from the nearest house down the road. I was walking back down the dirt road back to my car, it was pretty dark (hence no pictures...I tried, believe me). I hear some noise on the hill to the left so I stop. Then the bear wanders out of the woods onto the road about 15 feet in front of me. It was close enough that I got a very good idea of how big it was. It wasn't that big. Maybe 200 or 250lb? Just a little more than two Sebastians. It looked at me for about 3 seconds then slowly walked back into the woods. I stood there. I started to yell "Hey BEAR!" just to try to keep from running into it again, but apparently it didn't work because after I walked about another 25 yards down the road there it was sitting on the side of the road, a big hunk of black mass. I yelled real loud at it this time and he ran up in the woods about 50 feet or so and sat there. But it was pretty dark so I couldn't really tell if he stayed there long. I tried to take a couple pictures and got one of the flash's reflection off his eyes which is kind of cool but you can't tell it is a bear. Maybe I'll post it later.

OK then. North Carolina sure is eventful.

Here is the brook trout stuff I wanted to put up.

This is a map of the Tuckaseegee watershed. Dr. Peter Galbreath, the director of the Mountain Aquaculture Research Station here at Western, and some of his students conudcted a big survey of several wild brook trout populations of this watershed and a couple others in Western NC. Cullowhee, where I am currently writing from, is located pretty much where route 107 intersects the Tuck in the upper left hand portion of the map.

The black circles are streams with all southern strain brook trout (native). The white circles mark streams that are all northern strain brook trout (stocked from hatcheries as long as 150 years ago). The black and white circles indicate populations that are of mixed origins. While the data are not given for the Panthertown Valley creeks, Greenland and Panthertown Creeks, they are of mixed origin and visible on the map as the two streams that come together to form the stream just to the right of #34. These inferences are all based on genotypes at a single locus as identified by allozyme analysis. The tables below give more complete estimates of the genetic variation in these populations at other loci thought to be relevant indicators of geographic origin. CLICK THE MAP FOR A BIGGER PICTURE (scanners are for chumps... chumps with scanners).

This table gives sample sizes and actual allele frequencies, not just presence/absence as in the map. You can see that some streams, like #16 Moses Creek (where I saw the bear), are very close to fixed for the allele that indicates a southern origin, CK-A2*100. Moses Creek's frequency for the southern allele is 0.97. Some other creeks, like #24 Piney Mountain Creek and #25 Bearwallow Creek, are more evenly split at 0.48 and 0.52 for CK-A2*100 repectively. And some are almost fixed for the allele that indicates a northern origin, CK-A2*78, like #34 Slickens Creek.
While nobody really knows for sure which streams were stocked with northern hatchery brook trout, these frequencies probably reflect stocking history. However, some streams that we know were stocked with hatchery fish are now fixed for the southern strain, "in these cases, the hatchery brook trout apparently did not survive and/or successfully reproduce." (Galbreath p.5)


The next two tables contains data from other loci. At these loci, southern strain populations tend to be fixed for a certain allele, apparently which one varies between populations. Populations of at least some northern origin tend to be polymorphic at these loci. I didn't include tables that show populations fixed for CK-A2*100 (southern). All but 5 of these populations were fixed at these loci. Why those 5 are not I don't know. There is so much cool population genetics to be donw with these fish. Both tables below present data for the mixed populations. I included them because they illustrate the problems with using allozymes.

Allozymes are proteins that have very similar amino acid sequences but differ slightly. Therefore, they will have slightly different charges and will usually be resolvable when run in a gel (depending on their charges you will have to have a different gel, different current applied etc). Some allozymes will be "fast", i.e. will be more strongly charged in the right direction and therefore move farther down the gel than will the "slow" allozymes which are less strongly charged (or charged in the opposite way than the pole).

For a long time, people thought that different allozymes represented different alleles. Why are there slow and fast allozymes? Because they are coded for by slightly different sequences of nucleotides in the DNA, therefore there are so called fast and slow alleles. But it turns out that there are a lot of different ways that allozymes can vary in the charge that don't really have much to do with sequence differences. For example, alternative splicing can use the same "genes" and make different gene products. And there is post-translational processing that changes the structure (and therefore charge) of the protein after it is already formed. In fact, the idea of an allele or gene "for" something is becoming more and more nebulous. Secondly, and more importantly, allozymes don't pick up variation that doesn't change the charge of the protein. So you might score two allozymes on a gel as the same when in fact they actually aren't the same, they just have the same charge.

The first thing might be going on in the tables below. The sAAT-1.2 locus shows three different "alleles", *118, *100 and the "heterozygote". Heterozygosity is not a property of an allele, rather it is a property of a genotype. In other words, because these tables represent allele frequencies, the frequency of heterozygotes should simply be translated into 1 occurance of the *118 allele and one occurance of the *100 allele, not as an occurance of a heterozygote. But here there are apparently four bands that show up for a single fish so the proteins must be interacting in such a way to form two chimera allozymes that might be important functionally, but certainly don't represent directly variation in the DNA as there are only two alleles at this locus, brook trout at diploid. This is weird. I'm going to think about this some more. I might have this all wrong.

Anyway, the bottom line is that there is a lot of cool work to be done using more modern methods such as DNA sequence analysis, microsattelite markers etc. Maybe I'll drop out and become a fish/molecular biologist. That would be awesome.

OK. I'm going to ramble more about this stuff. Namely about ecological differences between northern and southern strain trout and also about how the brook trout in Panthertown Valley are indeed on average 114% bigger than other southern appalachian brook trout.


Galbreath, Peter. 2002. "FINAL REPORT to the North Carolina Wildlife Resources Commission fo rthe Cooperative Agreement entitled: Genetic Identification of Southern Appalachian Brook Trout Populations in North Carolina". State Depository Item #50261916.

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