Don, By genetic selection you can only constrain things that are genetically controlled. If a certain developmental form is the result of environmental factors rather than genetic control, a phenotype, rather than a genotype, then two widely different looking specimens may have the same essential genetic make-up. Therefore eliminating trees that have a particular form resulting from environmental factors will not affect the genetic make-up of the species at all. I don't know and really doubt there is any difference in the genetics of between a fat old wolfy hemlock and tall columnar hemlocks in the same general setting. So removing the tall columnar trees will not affect the frequency of multiple tops or lateral branching expressed in the trees if they are subject to the conditions favoring multiple tops, nor will it mean that the trees grown from the multi-top trees will show any more tendency to form multiple tops than columnar tree if the condition for producing columnar trees is present.
In a general population there are really only two main factors that result in genetic differentiation. So long as the tree can easily cross-pollinate or interbreed the genetic make-up of the population tends to be pretty uniform. A large distance say from one end of a species range to the other may result in genetic drift. The species at one end of the range may express different physical characteristics than those trees at the far end of the range because trees at the opposite ends of the range do not freely interbreed because of the distance. Whether this is because of a genetic difference or not is another question. Some genes are expressed because of environmental triggers and may be expressed differently in different areas. Other genetic traits, similar to blue eyed vs brown eyed traits in humans, may occur in different frequencies at different ends of the range. Some traits may be missing completely when comparing one end of the range to the other. But within the same general area where interbreeding can control in a contiguous population, the genetic make-up is for practical purposes uniform, even if the trees express different phenotypes. The other places where genetic variations occur are in disjunct populations and in populations in extreme environments. In these areas less frequently occurring genetic trait may be concentrated, while others are eliminated completely. Isolation from the general population allows any favorable mutation of genetic make-up to spread more quickly that is possible among the general population with a larger genetic pool. All species tend to show some genetic change through time, but he change is most rapid in isolated populations. If you look at the evolution of species over time, what you see may not be the slow change over time you expect, but a more rapid change. An isolated population develops a different genetic profile more quickly. Then if it is merged again with the general population through the natural ebb and flow of population boundaries with climate change, this change if advantageous may spread quickly through the general population, may spread and coexist as a separate entity across the range of the original population, or even replace the members of the original parent population with the new variety. To focus the point once more, I don't think there is any real genetic difference among the population of wolf trees and the population of columnar trees in a given locality, so eliminating one form will not change the genetic makeup of the population in general. Do I think some trees are genetically superior to others? Of course, individual trees may have different genetic compositions and some are "superior" to others. That is why efforts to save the biggest and best hemlock trees are worthwhile, because INDIVIDUALS may have superior genetic characteristics. Looking at a population scale, the populations in an area tends to be pretty uniform in genetic make-up. The population contains genes representing all the genetic variability available. Ed "Two roads diverged in a yellow wood, And sorry I could not travel both. " Robert Frost (1874–1963). Mountain Interval. 1920. ----- Original Message ----- From: DON BERTOLETTE To: [email protected] Sent: Monday, November 17, 2008 3:12 PM Subject: [ENTS] Re: old trees in the Inner Bluegrass Region of Kentucky Ed- I of course realize that you were constraining you comments to those species that rely on coppice reproduction. Leaving fat old 'wolfy' hemlocks, while taking tall columnar hemlocks, for example, is likely to retain genes that favor multiple tops, and lateral branching preference. Both phenotypes are needed for the diversity that favors survival, but the latter is sought after by the logger/mill interests. -DonRB ------------------------------------------------------------------------------ From: [EMAIL PROTECTED] To: [email protected] Subject: [ENTS] Re: old trees in the Inner Bluegrass Region of Kentucky Date: Mon, 17 Nov 2008 11:57:05 -0500 ENTS It is hard to lose genetic diversity in a species short of eliminating the entire population except for a handful of specimens or by selectively eliminating a specific genetic characteristic. Timbering is basically a non-selective process. The trees that sprout up after logging have pretty much the same genetic characteristics as the original population. They just don't have the same environment in which to grow. Trees or species that are adapted to extreme environments are the most vulnerable to genetic loss. These are populations that tend to concentrate genetic characteristics that are uncommon in the overall population and tend to preserve any advantageous mutations that would be lost among the larger genetic pool of the general population. The characteristics that are concentrated are still present in the general population and given enough time they could be potentially be concentrated again in an isolated population trying to adapt to the same extreme environment. Any true genetic variations limited to the isolated or extreme environment population would be lost with the effective elimination of the host population. Again simple cutting is non-selective, so it would require the population be removed and conditions altered so that the locality is not repopulated by the sprouts or offspring of the timbered or otherwise removed species. Ed "Two roads diverged in a yellow wood, And sorry I could not travel both. " Robert Frost (1874–1963). Mountain Interval. 1920. ----- Original Message ----- From: Ryan McEwan To: [email protected] Sent: Monday, November 17, 2008 9:54 AM Subject: [ENTS] Re: old trees in the Inner Bluegrass Region of Kentucky All: I would like to second Neil's main point- these trees may have passed through a bit of a genetic bottleneck due to human activities...but my gut tells me that we have only begun to discover the genetic flexibility trees. Plus, these trees were growing right on rocks, on a palisade, I would not infer much from their form. I bet you could grow "ideal" trees from one of their acorns. Than, again, if we think their form is a little off from the ideal, I think maybe that is an indication of our (non-biologically supportable) bias, not any real evaluation of the inferiority of the tree!!! This whole rat-race we are all involved in is ultimately about evolutionary fitness, and these trees have had about 200 extra years of acorn crops, so I reckon they are in much better shape than their fancy, straight-trunked, cousins who met the saw long-ago!! ryan -- Ryan McEwan The University of Dayton http://udbiology.com/content.php?id=1664 On Mon, Nov 17, 2008 at 7:27 AM, neil <[EMAIL PROTECTED]> wrote: Beth, That is great - I love the look of chinquapin oak [or chinkapin, however you wish to spell it. I'd be careful on estimating tree age from external characteristics. The last tree on the list was larger than most trees cored & yet ~ 1/4 of the potential ages. It lives next to a trail and an ephemeral stream. I'd guess it has less competition and more moisture availability yr round VS the other trees. BTW funny timing ENTS'ers: Floracliff and two other KY forests, including the 2000+ acre old-growth Blanton Forest, are featured in the book "Wildlands Philanthropy: The Great American Tradition". A nice article was written up in the local paper Saturday - http://www.kentucky.com/601/story/592954.html - w/ accompanying short articles on the three KY forests. neil On Nov 16, 8:39 pm, Beth Koebel <[EMAIL PROTECTED]> wrote: > Neil, > > Those ages are great! I am glad that you sent photos also as I believe I have found my first chinquapin oaks at a park in Pacific, Missouri. I now have to reevalute the age estimate for those trees. > > I will send a seperate email about the park and Pacific, Missouri later as soon as I find the connector between my camera and my pc. > > Beth > > <BR --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org You are subscribed to the Google Groups "ENTSTrees" group. To post to this group, send email to [email protected] To unsubscribe send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/entstrees?hl=en -~----------~----~----~----~------~----~------~--~---
