I was thinking about that, and yes, it's my thought. I have not read of any studies that might declare this, but - since it seems that the descriptive data is that it's survival of the fittest, OR -- "natural selection," how is it selected, who selects it? Use of language here could be a problem. For instance, do the organisms select their adaptation? By environment or simply by survival with the mutations into an environment ore conducive to their form? Or rather evolved form? Until, of course, they evolve so much they can't interbreed with former relatives, is that so? Because -- (I'm guessing here) -- the former relatives have died out? Or were too far away somehow, floated away maybe?
The environment selects. If an artic hare is suddenly thrust into a tropical jungle, do you think that its traits make it suitable for surviving and reproducing in that environment? There is no conscious selection. No selection clearinghouse where some entity is making a choice on who survives or who has the most offspring.
The environment is the sum total of internal and external conditions and the living and nonliving components (biotic and abiotic). Your internal organs are environments and parts of an environment. The desert and all the conditions that comprise deserts are a particular external environment. The weather. Predators. Parasites. Pathogens. Competition within a species and between different species. Rocks. Different soils. Mountains. All of that and more are the environment that organism live with or die with. The environment is not just the weather, which is what people often associate it with when discussing the environment.
Organisms do not select the adaptation. If a mutation provides for a even a slight advantage in a particular environment, that may be enough to ratchet up fitness. Biological fitness is basically the number of viable offspring that an organism has. If it has more than other members of its population and its offspring have more, then those organisms have a greater chance of perpetuating their genes within that population in a particular environment.
At some point, a population may undergo enough genetic and phenotypic changes that they can no longer interbreed with related populations from the same ancestry. There is no set point of changes required or established timeframe for this, though it normally occurs over 10's or 100's of thousands to millions of years. It depends on the stability of the environment among many other factors. Two populations separated by some natural barrier like an increasingly impassable river or canyon can evolve independently into new and separate species.
The ancestral population (distant relatives) can die out, but it does not have to. The theory of evolution doesn't stipulate that an ancestral population must cease to exist. Again, extinction would depend on numerous factors of the environment. In a species with a very large range, say millions of square miles, changes in a small part of the range can occur, while the rest of the range remains stable. Those members of the former population in that small portion of range that changed would be under different environmental selection. If the change reverts to the previous conditions, any selection would eventually be erased, but if it does not revert or changes further, then selection would drive change in that part of the population toward speciation.
It is a lot to take in and consider. Many events occurring over large geographies and vast spans of time. With corroborating evidence found in many disparate fields of study. That is why those of us that have had training in biology, made our careers in studying that evidence, become frustrated when people persistently claim there is no evidence or that it is a matter of interpretation without ever offering a valid counter interpretation that does not involve subjective belief that has no evidence to sustain it.
If you look at the fossil record, both at individual fossils or in groups across time and space, the theory explains what we see and tests can be run to accept or reject hypotheses. Ultimately the theory itself is constantly tested. The same can be done with the geological evidence. The morphological evidence of extant organisms. The genetics of extant organisms. And so on across many fields. To date, all of this evidence supports the theory.
The theory is not consistent with a literal interpretation of Genesis or with any other creation story that is known. What it does not do is say that there is or is not God. For me personally, that means that we do not really understand Genesis and should view it allegorically rather than literally. Taking that position does not eliminate God and is honest.
And plus, tadpoles come from frogs. Insofar as science knows, right? And I DO mean know, not conjecture, that frogs come from something else. Yes, we KNOW tadpoles come from frogs. We also KNOW they develop to be frogs. You want to say this is evidence (I can't use the word prove, because 'evidently' I'm not supposed to use the word 'proof' in science) of evolution? (I don't think so, apparently you do. But I don't.) Thanks for the post, though.
