An interaction in which an animal feeds on plants is called

Which are forms of nitrogen that are usable by humans

What was the land like over 500 million years ago? what was under the sea?

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