The giant panda's change in diet from primarily meat to primarily plants is environmental change.
They discovered that there is a transformation in the T1R1 gene. The gene encodes for T1R1 protein which is an umami taste receptor. The transformation turns T1R1 into a pseudo gene: a gene which is not extended represented.
As a result, pandas cannot taste the umami taste of flesh and slowly lost an appeal to meat.
Thus, this could be the answer.
To learn more about giant panda's click here:
https://brainly.com/question/21394774
#SPJ1