Ontogeny recapitulates phylogeny, anyone?
Funny. I just remember reading an anti-evolution site somewhere on the web. It said, “Not one fossil with part-fins part-legs has ever been found.” I thought, couldn’t I just go pluck an adolescent frog out of a lake, in the middle of recapitulating its phylogeny, and fossilize it?
Am I right in remembering that there is a phase in amphibian development where they have little legs but retain their tadpole tails and gills for a while too?
“. . .an evolutionary “child” to be successful it has to be significantly more adept to its environment that the previous evolution. Therefore, the immediate evolution and it’s predecessor could not exist in symbiance without the possibility of the newer being choked out due to it’s lack of numbers.”
There is a long stretch of unproved assertion between “without the possibility” and the inevitabilty inherent in acceptance of the existance of one species proving it not to be related to any existing species. This arguement is very weak. The existance of several unrelated species (for example dogs, hyeans, and jackels)sharing an environmental “niche” in many cases makes it far less than weak, but completely spurious.
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Can you rephrase that? I … have this … friend … who has trouble with really really long sentences. Can you help m- err, can you help him out with it?
There is a possibility that a “child” species might overwhelm and eliminate it’s “parent” species. While it may be true that this happens in some, many, or even most cases, it in no way implies that it must happen. Since the argument was used to support the contention that humans cannot be descendant from apes because there still are apes, it assumes that that possibility is an inevitable outcome. A very weak argument.
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According to the punctuated equilibrium theory, species tend to continue without significant change for most of their “lifetimes.” At some point, a population on the edge (literally or metaphorically) of that species’ ecospace gets pinched off, and through genetic drift and the force of that particular biome, develops characteristics that make it distinct from the main population. At that point, speciation is likely to occur. (Note that this also holds true for the development of {biological} races and subspecies, hence “is likely to” rather than “will.”)
When the circumstance pinching off the new species ceases, the new species can spread across the range of the old, and:
(a) replace it, if it has a better adaptation that makes it more “fit”
(b) live alongside it, if its adaptation puts it in a slightly different econiche
© fail to replace across most of the range, if its adaptation was specific for the particular biome in which it speciated.