Abstract Understanding the genetic targets of natural selection is one of the most challenging goals of population genetics. Some of the earliest candidate genes were identified from associations between allozyme allele frequencies and environmental variation. One such example is the clinal polymorphism in the arginine kinase (Ak) gene in the marine snail Littorina fabalis. https://www.diegojavierfares.com/top-super-SOLD-Used-Olympia-Cremina-1979-Refurbished-120-volt-Brown-save-big/