Each trait of a frog is meant for something. Natural Selection shows different processes to get traits and how they change to adapt to their environment. Many frogs look different depending on their environment. Some have camouflage to hide from predators.
If the species of frog become over populated, food will become scarce and it will be tough to have a stable environment with all the frogs trying to get their prey. But this allows them to also have a better chance at not decreasing the population since only some babies survive so this allows them to still have population when off spring dies.
Genetic variation or mutation can either be helpful or terrible. If a frog was yellow, it would be at a disadvantage since it is easier to see when trying to catch it. Grey frogs blend in the their environment allowing predators to have a tough time to see and catch them.
When a trait is more common or helps the population greatly, that trait will be more common for the off spring. That is called selection. This will allow a trait to help that species thrive.
Adaptation can help an organism survive in their new environment. A frog can adapt to breathing on air so instead of living just in the water, they can breathe on air as they grow older. Adaptations allow changes that are needed for an organism to survive.
In conclusion, natural selection can help animals survive and adapt to thrive. Some can be bad and hurt the species while others can improve the population. Natural selection helps animals live, and not become extinct.