Natural selection leads to this by changes in the environment. Animals are forced to adapt due to the changes.
Overproduction and the Struggle to Survive
Adaptation increases its fitness because it allows the organism to swim fast with its fins. This will increase its survival.
Survival and Reproduction of the Fittest
The genetic variation in the Leather-back sea turtle is that some of the turtles have strong fins and some have weaker fins.The size of their fin contributes to the speed they go in the water.
Changes in Gene Pool
Leather back Sea turtles lay about 110 eggs but not all survive. A lot of eggs are hatched which are seen by predators. As for those with stronger fins, they can swim quickly to escape the predator.
The turtles that have weaker flippers will most likely be eaten by its predator because they can't swim fast enough to get far away to safety.The faster turtles will have a higher chance of surviving meaning they'll create offspring with the same adaptation its parents inherited.
The sea turtles with stronger fins will survive and increase as time goes by. The ones with weaker fins will decrease having less turtles with weak fins.