Which of these is an environmental effect of building dams?
a.) sediment buids up downstream
b.) increased fertility downstream
c.) increased water teperture upstream
d.) weed growth upstream

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