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Politics : Formerly About Advanced Micro Devices -- Ignore unavailable to you. Want to Upgrade?

To: Brumar89 who wrote (383427)	5/9/2008 1:39:33 PM
From: combjelly	Read Replies (1) \| Respond to of 1586777

"So do Christian professors flog their faith in class there?" Not in CS and EE departments. Don't know about others. I do know that a group of profs take out an ad periodically in the newspaper for that. "And yet, you didn't describe any of those many differences." I don't see the point of a text wall. Sometimes it is far simpler to enumerate the set of similarities. Which I did. One problem is, which type of abiogenesis are you talking about? "And chemical evolution?" Which version of abiogenesis do you have in mind? All are hypothetical. None are very complete. While some observational evidence exists for many of them, none are particularly compelling. "So do prokaryote species reproduction (by division of course) sometimes produce another prokaryote species?" Prokaryotes have a very high rate of mutation because they don't the DNA checking and repair mechanisms that eucharyotes do. So the boundaries between species are pretty vague. Defining a “species” can be quite challenging, even for macro-organisms. The boundry between ecological variation and speciation is often vague for certain organisms, none more than prokaryotes. Closely related species, which is often determined by comparison of small subunit ribosomal sequences (16S rRNA) may have radically different metabolic capabilities, and the presence of horizontal gene transfer lessens the reliability of molecular characters in resolving evolutionary relationships. The technical definition of species used today is 70% sequence similarity between genomes using DNA-DNA reannealing methods. The use of sequence homology among small subunit ribosomal genes has for many years been another standard for defining a species. Research has indicated that a 97% sequence homology between 16S rRNA often corresponds to 70% genome similarity. Other techniques include the use of multi-loci sequence typing (MLST), where several genes, determined to be suitable taxonomic markers, are used to generate a single phylogeny for a set of species. The genes are then aligned, and alignments are concatenated into a single data set with multiple partitions. The use of MLST is a natural lead-in to whole genome based phylogeny, where gene sequences as well as chromosome structural features are incorporated into a single analysis. Development of genome-based phylogenetic techniques may lead to a better understanding of the interplay between vertical inheritence, horizontal gene transfers, and environmental factors in prokaryotic speciation. wiki.biomine.skelleftea.se "So are chihuahuas and wolfhounds not members of the same species?" Again, taxonomists don't consider domesticated animals except as a single species. According to the rules for other creatures, they should be different species. "So I am using a firm definition of species." Well, that would be an idiosyncratic definition. "So why all the observations about sickle cell carring blacks and Ashkenazi Jews?" I originally used the example of the Ashkenazi to show how a restricted breeding population can acquire characteristics in a relatively short period of time. We know when they were dispersed and their isolation from the surrounding population has been documented. As were their living conditions. We can be pretty sure what their assemblage of characteristics were before the Diaspora because not all were dispersed. So it is a perfect example of evolution in action. The sickle cell example was just to bring in another case where heterozygous conditions conferred an advantage and the homozygous conditions was debilitating. Although it should be noted that the Ashkenazi defects are much more debilitating, often killing at a young age. Which is indicative of the Ashkenazi mutations being relatively recent.