Answer:
Species are changing, natural selection is happening
Step-by-step explanation:
There are many small, unnoticeable changes occuring in animals everday. Depending on whether these changes are helpful or unhelpful, the animal and its special features, will either be eliminated (through the process of natural selection) or embraced by others. If the traits are helpful, and therefore more dominant/attractive, it will ultimately lead to a split off, more dominant group of animals that all have the same adaptation, which allows the animals to out perform others.
**The reason you can't always see natural selection is because it's often a slow process. Also, if an animal's mental or physical traits change for the worse, the animal doesn't always live a full life, and doesn't reproduce. If the animal with the new traits doesn't reproduce (because the traits are not helpful and therefore unwanted), then that animal's traits are not allowed in the environment.**