Quetzal writes:
There is NO one, single, irrefutable, powerful proof of evolution. Anyone who thinks otherwise is kidding themselves.
On the other hand, there are dozens if not hundreds of different lines of evidence from a myriad of different disciplines that, taken in toto, provide sufficient evidence that to deny the fact of organic evolution would be tantamount to denying the existence of light or gravity.
I thought that(...) it might be interesting to poll the forum to see what we can come up with as a list of lines of evidence which we feel are the most compelling. Maybe it could be added as a FAQ to the site, or something. Not specific cases (such as a particular transitional fossil or the evolution of an antifreeze glycopeptide from a digestive enzyme in Arctic fish, etc), but rather the broader lines of evidence.
I'll start out with a few that I consider indicative, and then leave it open for others to add:
1. biogeography: why are species distributed around the globe as they are? Why are closely related species found geographically near to each other? Why are continental islands full of terrestrial endemics that are different from anywhere else - but whose nearest relatives are on the adjacent continental masses? Why are oceanic islands filled with endemic birds, insects and plant life, but few if any mammals?
2. convergent forms: Why are similar adaptations to specific environmental conditions found in vastly different organisms (i.e., placental wolves and marsupial Thylacinus cynocephalus) in widely separated parts of the globe? Why DOES the diversity of life fit so neatly into a nested hierarchy of similarity?
3. geology/paleontology: Why are the layers of rock so conformal around the world - to the point that you can correlate ages and sequences from one part of the world to another in many cases? Why are the sequences of fossils invariably time-correlated, regardless of where they are? Why don't we find mammals or angiosperms, for instance, in the oldest basement rocks?
4. molecular biology: Why can we often correlate relationships between organisms based on molecular biology with relationships based on morphology?
5. Ecology and population genetics: Why do we see variation from one end of a species range to the other, such that at the extremes they appear as completely different species? How can we explain ecological specialization, local extinctions, the effects of ecosystem degradation, the sanctuary effect, ecological zonation, niche partitioning, etc?