How does your diaphragm contracting in inhaling?

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

Why has two different alleles for the same trait?

Development has provided electrically for less money but what may be considered a cause of nuclear power