Is That on the Map, George?

A quick survey of covered ground, just to make sure we're all on the same page.

1) Biological relationships necessitate common ancestry, per Darwinism. Descent with modification. Accordingly, the theory demands continuity between species, as illustrated by our discussion of vertebrate sequences this week.

2) The problem of discontinuity. As has been pointed out repeatedly, neither the existing order of living organisms nor the fossil record corroborates the idea of descent from common ancestors with modification--the intermediary transitional forms are scanty and inconclusive, not robustly present with a clear line of descent.

3) The relationship of phenotype to genotype. Natural selection favors the organisms whose characteristics best allow them to compete and reproduce. These are physical characteristics, but ultimately it is not these specific characteristics upon which natural selection works but the genes that specify or direct these physical traits. In other words, the phenotype is produced by the genotype, with the help of the environment.

Keep that last sentence in mind as we go forward.