Srimad Bhagavatam Canto 03, Chapter 07, Text 31

SB 3.7.31

pasanda-patha-vaisamyam
 pratiloma-nivesanam
jivasya gatayo yas ca
 yavatir guna-karmajah
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
Please also describe the imperfections and contradictions of the faithless atheists, the situation of crossbreeding, and the movements of the living entities in various species of life according to their particular modes of nature and work.
 
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The combination of living entities in different modes of material nature is called crossbreeding. The faithless atheists do not believe in the existence of God, and thus their paths of philosophy are contradictory. Atheistic philosophies never agree with one another. Different species of life are evidence of varieties of mixtures of the modes of material nature.
Srimad Bhagavatam Canto 03, Chapter 07, Text 30
Srimad Bhagavatam Canto 03, Chapter 07, Text 32