Aspecies of small lizard has three color forms, pale gray, brown, and black. in its original range, the colors of the rocky environment were mixed from pale gray to very dark, and the population had an even mix of all three color forms. the blending of colors with their environment the lizards hide from predators. a group of these lizards ended up on an island with all gray rocks. eventually, only gray lizards remained. this is an example of

Directional Selection

Explanation:

In population genetics, directional selection also know as positive selection is a mode of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.