Imported weed diversification supports macro-evolution

Faith,I agree it's not macroevolution, but speciation is not "just ordinary variation according to Mendelian principles of inheritance". The plants can no longer interbreed. Nowt to do with races or "varieties" of the same species.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

kuresu,To paraphrase the definition of macroevolution given by Levinton in "Genetics, Paleontology & Macroevolution": Change that is indicative of placement in higher taxonomic ranks. In this case, your example does not meet the standard. I think you even have a problem shoe-horning it into your own preferred definition, it certainly isn't change on a grand scale.The example you describe is good old common or garden microevolution that resulted in genetic isolation from the parent species. Speciation, to be sure, but speciation does not equal macroevolution.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

kurusu, But it still ain't macro. Even this doesn't include speciation as being macroevolution.I suppose I should have been unlazy enough to give the full definition rather than the one from memory:(Levinton 1983) "The sum of those processes that explain the character-state transitions that diagnose evolutionary differences of major taxonomic rank".But even the older & less accurate "evolution above the species level" definition doesn't allow Goatsbeard's speciation entry into the macroevolutionary fold.The term "macroevolution" was always intended to mean something akin to large-scale evolutionary change, so a definition that reflects that is more efficacious & honest than one that includes "mere" reproductive isolation (ie speciation).Don't get me wrong, kurusu, it's wonderful example of speciation, just not macroevolution.MarkThis message has been edited by mark24, 03-25-2006 07:51 PM

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Belfry, I'm not inclined to agree. Chihuahua & Great Dane genes are capable of gene flow, it might take a generation or two to get a Great Dane to breed with a smaller variety, & a Chihuahua with a larger & so on, but eventually, a Great Dane gene can easily get into a Chihuahua population & vice versa.If individuals in a population can't directly interbreed, but can still pass on genes to decendents of those individuals, then under the biological species concept they are still a "good" species.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Faith, Yes there is, but that's not the point. There are more differences within supposed races, than between them. Think about it. What that means is that in order to maintain "races" we are forced cherry pick certain traits & attribute them to "races", whilst ignoring the rest of the data we have that actually contradicts the notion. No way to objectively define human groups.Mark

Faith, But that's just it, Faith, there is no genetic specificity that you get with other breeds & varieties. There is more genetic difference within races than between them. There is no biological rationale for race.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Belfry, And those that work with asexually reproducing organisms find it sexo-centric ! I'm sure you are aware that all species concepts have their share of problems. At the end of the day biologists come running back to daddy, or something centred around the BSC. Would they? That may be their first impression, but even using other species concepts they would after a little study realise that anatomically, genetically & phylogenetically they should be the same species, as compared to & distinct from foxes, for example.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

kurusu, Speciation is a part of a process that may result in macroevolution at some point, when compared to the "start" point.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Faith, No, races as you understand them were not produced. It is in fact genetics that has taught us this.There are populations of black africans that are more dissimilar to each other than whites are to them, genetically speaking. Australian aborigines are more similar to white caucasians than black africans. This means that we do when we declare races is that we are taking a small part of a large character set & attributing race in this way. Unfortunately we are also ignoring the larger picture which leads us to false conclusions. None of the groups you cited are races. And as for assigning races to groups because of OBSERVABLE characters, how about big noses? They are observable. Eye colour? It goes on. Why not. Dark skin is not indicative of common descent in human populations, so why lump them together because of it?MarkThis message has been edited by mark24, 03-26-2006 02:26 PM

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Faith,In addition to Schraf's post, what race are these children? Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't

Faith, You said it was OBSERVABLE. It is therefore implicit that you can place people into races by observation.On the one hand you think you can recognise a Norwegian from an Italian, an Arab from a Mongolian, but refuse to place indiginous tribal folk into one of the five major races!THIS is why races are bunk, Faith, because despite "talking about something OBSERVABLE", you are still unable to put tribespeople into racial slots.Mark

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There are 10 kinds of people in this world; those that understand binary, & those that don't