Sea turtles bury their eggs on the beach. When the offspring hatch from the nest, they dig out from the sand and crawl down the beach
to the ocean. A study compared the rate that newly hatched turtles
moved toward the ocean from their nest, which affected the amount
of time they were exposed to predators. The rate of turtle movement
was different between baby turtles from different nests (which
had different mothers). Offspring from some nests ran faster than
others. If the rate of movement is going to evolve in this population,
what must also be true of the rate differences? Provide support for
your explanation.