Evolution Follows the Path of Least Resistance

Over at Jerry Coyne’s blog, biologist Greg Mayer wrote:

One of the most important lessons of comparative anatomy is that evolution usually proceeds by the modification of pre-existing structures (or, stated more precisely, the modification of the pre-existing developmental programs that produce those structures). Certain changes are easier to evolve because the developmental system can be modified to produce them—evolution follows the developmental path of least resistance. In terms of the skeleton of vertebrates, this means that most evolutionary changes are reduction, fusion, loss, lengthening, shortening, thickening,  and narrowing of bones. Evolution uses what’s already there, and rarely do wholly new structures arise.  (from “Tinkering with elephants’ feet”)

All of this is true, yet we can proceed beyond this conventional thinking and ask a couple of questions:

WHY does evolution follow the developmental path of least resistance?

WHAT are the implications of evolution following the developmental path of least resistance?

Notice a pattern?

Only have the time these days to share the abstracts of studies whose data support the hypothesis of FLE.  Check this one out:

SNARE protein-driven secretion of neurotransmitters from synaptic vesicles is at the center of neuronal communication. In the absence of the cytosolic protein Munc18-1, synaptic secretion comes to a halt.