What changes in the ecosystem will take place during secondary succession A. The flowers will deplete the soil of nutrients in the area will become a desert

Option D, There is a lack of genetic variation for selection  to act upon

Explanation:

Genetic variation defines the differences with in the organism of the same species and have been a driving force for selection.  

Since the population of panther has reduced to a very small number, it is very obvious that the gene pool has also reduced which in turn has reduced the genetic variation and hence the lack of genetic variation induces inbreeding depression which further restricts evolution.

Hence, option D is correct