How do you explain the genotypes and phenotypes of skin color

Human skin color is a polygenic trait, which means that multiple gene loci (with different alleles) are involved in its expression. ... Because of that, there is the enormous number of possible genotypes for the skin color and as a result, the phenotypes vary from the darkest brown to the lightest hues

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.