Posted on 11/27/2005 7:11:52 AM PST by Pharmboy
If the major physiological difference between two species is that one has a shorter gastrointestinal tract resulting in a lower digestibility of foods, thus requiring slightly different dietary needs, would these critters be different 'kinds'?
Not a difference in kind. That could be microevolution as usual or one designer copying another, but they have the same body parts and the same basic sort of plan. A better example would be ducks and penguins, again same basic body parts and actually the same basic plan for life if you view what the penguin does as "flying" through water.
Please can you supply the biological definition of a "kind".
Please can you supply the details of the physical mechanism that prevents a large number of tiny changes accumulating into the evolution of a different "kind".
RODHOCETUS BALOCHISTANENSIS, a newly discovered species of ancient whale, is reconstructed here. Discovered in 47-million-year-old deposits in Pakistan, this beast had well-developed limbs that would have enabled sea-lion-like locomotion on land.
Source: Whence Whales?
Not a difference in kind.
Yet frogs are vastly different to toads. Far more different than say chimpanzees and gorillas. Do you think that chimps and gorillas are the same kind? What about chimps, gorillas, baboons, gibbons, and orangutans?
I've alrady done that above.
>Please can you supply the details of the physical mechanism that prevents a large number of tiny changes accumulating into the evolution of a different "kind".
It's called "natural selection", and that is precisely what it does.
Yet they who evolved the slowest, evolved the most, while they who evolved the fastest evolved the least....that seems a tad illogical
What significant difference between dogs, wolves, and cats (and BTW when you say cats are you distinguishing between lions, tigers, pumas, lynx, panthers, cougars, wildcats, domestic cats, cheetahs, leopards) would prevent what you would term cumulative microevolution from bridging the gap between them, in the same way for example that finches can develop different beaks?
Stasis only results from natural selection when there is no change in the organism's environment or relationship with other organisms. Your link brings up evolution of the flagellum which, while interesting, is another subject entirely.
You concede that frogs and toads might have a common ancestor, which places "kind" at the family level. As pointed out, though, frogs and toads have a lot of key differences. How is it that frogs and toads (both members of the order Anura) can all have a common ancestor but not cats and dogs (both members of the order Carnivora)? The level of difference is comparable.
Also is it possible that frogs/toads (order Anura) and salamanders (order Caudata) are the same "kind"? Transitional fossils (like the one I posted earlier) and the existence of Ascaphidae (frogs with vestigial tails) seem to conribute evidence to this. If they're not the same "kind", where does the inability of one "kind" to evolve to another begin here? If they are the same "kind", this pushes the category of "kind" back to the level of biological Order.
This "kind" thing is very confusing. I vote we scrap it.
That bothered me a bit also. It seems our species has come a VERY long way from the ape-like creatures in 5 mm years. Hard to reconcile--PH, any thoughts?
Someone else has already given one of the obvious rejoinders to the "stasis" element of your link. So I'll address the "of what use is 2% of xxx?" element. The answer is actually a great deal. For example an eye that is 1% as effective as the modern vertebrate eye would give its possessor a literally killing advantage over completely blind opposition. Likewise a fin that was 1% of the way towards being a leg would allow a fish that lived in shallow water marshes massive advantage over its competitors, particularly at a time when the land lacked all animal competition. The "of what use is x%" argument is essentially an argument from incredulity, and points to a failure in the imagination of those posing it.
It's an in kind development grant for the scientifically illiterate.
You are soooo kind.
That's "kind" of the whole point here, and why taxonomists don't use it a a classification scheme.
I think it's sloppy writing. Perhaps the intent was to say that because our species appeared so recently -- less than a million years ago (give or take) -- then our evolution took a long time, thus we were "slow" to arrive. Nothing else makes any sense.
Basically the whole "kind" thing comes from people whose level of biological knowledge appears to be at "The Big Picture Book of Animals" that we all loved when we were 5 years old. In books like that frogs and toads get lumped together (if toads even get a mention) and the entire insect kingdom gets one page and three species if you are lucky. No wonder that some people find Noah's Ark possible.
Well, I'm glad I was not alone in being confused. Your explanation could be correct--and if that's it, some very sloppy writing on their part. Thanks.
Funny, statisticians have no problem with the concept.
So are you saying “A rat is a pig is a dog is a boy.”
Doubtless that is some kind of brilliant rejoinder that means something to you, but you'll have to run it by me in smaller stages so I can get what you are saying.
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