How is climate change today SIMILAR from the climate changes which wiped out the dinosaurs?

What is the primary function of the nervous system?

Asquirrel population lives in an area. over many years, a river in that area grows wider and stronger, eventually forming a canyon. the squirrel populations on the two sides of the canyon can no longer mate with each other and ultimately form distinct species. this is an example of

Under which of the following circumstances would natural selection not operate on an organism