Looking at the image why is evolution not linear (a single line) but instead like branches of a tree? *
(A) because some species share a common ancestor
(b) not every species is related unless you go far back enough in time

4. multiple crosses were made between true-breeding lines of black and yellow labrador retrievers. all the f1 progeny were black. when these progeny were intercrossed, they produced an f2 consisting of 91 black, 39 yellow and 30 chocolate. a. propose an explanation for the inheritance of coat color in labradors. b. propose a biochemical pathway for coat color determination and indicate how the relevant genes control coat coloration.