The Mother Cell is a vector molecule that Reiden Global used in all of its products. The molecule caused rapid mutations in the animal kingdom, and eventually some humans as well.
It hyperevolved and mutated animals, in addition to giving them a hive mentality enabling cross species communication that told animals not to prey on each other but rather on humans. However, this didn't seem to cause any negative effects to the animals, as they can still be seen thriving in the second season.
List of several animals that changed by The Mother Cell:
pupil dilation (also called Delta Determinant)
loss of fear
hive mind
Aggression
Lions: remote communication
Bears: endoskeletons/ hard shell-like skin
Rats: asexual reproduction
Birds: each and any species can talk to each other
Ants: generate electricity
Moles and Sloths: earthquake generation
Snakes: poison generation by their shedding glass like skin
Lizards: ice generation