Overview
I'm working on a biology writing question and need the explanation and answer to help me learn.
The neutral theory of molecular evolution holds that most evolutionary changes occur at the molecular level, and most of the variation within and between species are due to random genetic drift of mutant alleles that are selectively neutral. The theory applies only for evolution at the molecular level and is compatible with phenotypic evolution (physically seen traits) being shaped by natural selection as postulated by Charles Darwin. Some evolutionary biologists have argued that the neutral theory should be taken as the null (or invalid) hypothesis to explain genetic variation within species or populations and genetic differences among them. In this view, adaptation and natural selection should be the preferred explanation only if genetic drift cannot explain the data. Others might argue that since there is so much evidence that natural selection has shaped species’ characteristics, natural selection should be the explanation of choice, and that the burden of proof should fall on advocates of the neutral theory. Why might one of these points of view be more convincing than the other? Natural selection or molecular modifications?