When nature "selects" a variation, that means that the trait:
Gets passed along from generation to generation
Causes the population to shrink
Has brought about a new species
Helps prey escape predators
HEL ITS URGEN

When Nature selects a variation, that means the trait gets passed along from generation to generation.

Explanation: The trait might not be beneficial to the species, but that won't stop it from passing it down from parent to offspring. We don't know if the variation will bring a new species, or cause the population to shrink. We don't even know if it will help the prey escape predators. But we do know that all traits are passed along from generation to generation.

explanation:

the fossil record extends back to a dog-like ancestor some 55 million years ago, which gave rise to the first horse-like species 55 to 42 million years ago in the genus eohippus.

straight or amphibians are homeothermic to thermal