How many sub layers does the earths layer have

Organisms that successfully adapt will leave to grownone of the above

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

Is this mrna or rna need need the answer in a hurry