That would require ID to be science... -----Original Message----- From: G Money [mailto:[email protected]] Sent: Tuesday, June 08, 2010 10:47 AM To: cf-community Subject: Re: Speciation was: Thought this was great
This is wonderful. I would love to see an equally well crafted summary of the "science" of intelligent design...if anyone has that in them. Great stuff Judah. On Mon, Jun 7, 2010 at 4:29 PM, Judah McAuley <[email protected]> wrote: > > Evolution is a very commonly misunderstood term and the > socio-political use of the word doesn't really match up with the > scientific use, leaving things rather muddy. Even within the > scientific realm there is a lot you have to specify in order to really > get to what you mean by the word, it's a big discipline. It is kind of > like saying "I don't believe in Physics" when really you may just be > disputing the validity of String Theory or the Copenhagen > Interpretation. > > Getting back to macro evolution and micro evolution, those are terms > commonly used outside of the discipline to distinguish between > phenotypic (stuff you can see, like beak shape or fur color) change > within a species over time versus the act of speciation, that is, the > formation of a new species. The first kind is often called micro > evolution and is really kind of a red herring because, broadly > speaking, everyone has agreed on that for hundreds of years. People > saw the change in heritable characteristics (those that can be passed > on to children) long before the time of Darwin and Lyle. Gregor Mendel > laid out the concept of what we now call Mendelian Genetics (obviously > he didn't know anything about DNA), showing how heritable traits were > passed on in pea plants at the same time that Darwin was publishing > his work. Mendel was a priest and there was no theological trouble > with his work because it was just documenting how a species passes on > variation. Those who try to dispute Creationism by showing incremental > evolution within a species are doing them a disservice because that > really isn't the heart of the dispute at all. > > Then we get to what Kris is calling Macro Evolution, which is a term > used to refer to the production of a new species from an existing > species. This is where the dispute over "evolution" really comes into > play, it isn't a disagreement about whether things evolve, it is a > disagreement about speciation. Darwin called his work "On the Origin > of Species" or, in the long form, "On the Origin of Species by Means > of Natural Selection, or the Preservation of Favoured Races in the > Struggle for Life". The title of his work is the key here, he wanted > to show a mechanism for the creation of new species from existing > species. > > Darwin had a couple of key insights and, put together, they are > generally known as "descent with modifications and preferential > survival". It works thusly: > > 1. In every generation, there are multiple values in a population for > a heritable trait > 2. Those values are not passed on with complete fidelity. Some > offspring will get one value for a trait, some another value, some a > value not obviously present in the parents. > 3. Those values can have differential survival outcomes, ie, members > with one value may be more likely to survive and pass on that value > than members with another value. > > This, in a nutshell, forms the basis of Evolution, why species change. > Darwin then went on to show that that algorithm (though he would not > have called it that) can produce speciation. As a side note, people > differ in their distinction on what constitutes a species. Some people > take a very cut and dried line that says two populations are different > species if they cannot breed and produce viable offspring. While that > is the easiest way to define it, it isn't very useful in a practical > context because then you have to explain why lions and tigers aren't > different species. More generally, a species is usually defined as a > population that is genetically and physiologically distinct and that > does not naturally interbreed with another population. So while lions > and tigers can mate and produce offspring, they do not do so in the > wild and they form distinct populations and have important genetic and > physiological differences. The bit about interbreeding, of course, > goes out the window when you are talking about asexually reproducing > (and especially self propagating) organisms. > > There are a couple different methods of speciation normally > recognized. The most common kinds are called Allopatric and Peripatric > speciation. These both are a result of separation of populations of a > given species, usually geographically. For instance, a segmenting of > the range of a species due to deforestation where the populations in > the two new regions no longer encounter one another much because their > range isn't contiguous any longer. These two populations start out > with differences in their genetic make up that would normally be a > wash when the whole population is interbreeding. However, due to the > lack of ongoing contact between the populations, the differences > between the pool of variation combined with the continuing process of > descent with modification and natural selection can produce enough > variation over many generations to make the two populations distinct > enough that they not only do not but can not interbreed successfully. > This is known as allopatric speciation. > > Peripatric speciation is a more extreme version of allopatric > speciation, usually involving substantial geographic separation like > the formation or colonization of islands. It is also the subject of > the discipline known as Island Biogeography. Basically, there are > times when otherwise unreachable spots are reached by a group of > individuals, like when land bridges appear during periods of extremely > low sea levels. These new populations may then be cut off again and > this new, isolated, population will be characterized by having a very > small pool of genetic diversity to start with. This is known as the > Founder Effect. In these cases, traits which might be very rare in the > parent population become much more common in the child population > because of the small number of individuals contributing to the overall > starting pool. The founder effect, combined with the fact that > natural selection often rewards different characteristics in a small, > island setting than it does on a large contiguous region, often means > that these isolated populations will diverge quickly and dramatically > from the parent population. Peripatric speciation is the reason why > Australia largely has marsupial mammals whereas marsupial mammals are > quite rare everywhere else. They got cut off early in the changes in > mammalian physiology and due to low gene flow in from the outside, the > trend continued there but diverged elsewhere. > > There are other types of speciation discussed, such as sympatric > speciation. Sympatric speciation is a hotly disputed area, however, as > it hypothesizes how two species can arise in the same area without > substantial separation. As far as I'm aware, there aren't any > instances of this type of speciation that have been shown to happen in > the wild, but I haven't really studied the subject in awhile, so I'm > not sure what the current state of research on sympatric speciation > is. > > Speciation has been observed in the laboratory in a number of > experiments. The most common (among animals) are with Drosophila, > fruit flies, because of their short generation time, wide use in the > lab and high rate of natural genetic variability. A summary of some of > the instances of observed speciation can be found here: > http://www.talkorigins.org/faqs/faq-speciation.html It also contains > a further discussion of what constitutes a species and a discussion of > the Biological Species Model. > > A lot to digest, I know, but hopefully it will help people thinking > about the arguments around Evolution and, more specially, that we are > really talking about an argument regarding speciation. > > Cheers, > Judah > > > > On Mon, Jun 7, 2010 at 11:08 AM, Kris Sisk <[email protected]> wrote: > > > >>Is the dogs/wolves example even an example of evolution? Isn't it > >>domestication? > >> > > > > Domestication is usually a perfect example of that type of evolution. I > think that micro evolution is the one that would be wolves to dogs, but I > never could keep the two terms straight for some reason. Another example > would be the finches observed by Darwin just prior to writing the Origin of > the Species. They had obviously evolved differing beaks for differing > purposes, but they were all still finches. If those finches had evolved into > hummingbirds, for example, that would be macro evolution (assuming I haven't > gotten the two terms mixed up). > > > > Now before anyone jumps down my throat, I'm just illustrating the point. > > > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Order the Adobe Coldfusion Anthology now! http://www.amazon.com/Adobe-Coldfusion-Anthology-Michael-Dinowitz/dp/1430272155/?tag=houseoffusion Archive: http://www.houseoffusion.com/groups/cf-community/message.cfm/messageid:320638 Subscription: http://www.houseoffusion.com/groups/cf-community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/groups/cf-community/unsubscribe.cfm
