Nthe cross shown here, involving two linked genes, ebony (e) and claret (ca) in drosophila, where crossing over does not occur in males, offspring were produced in this phenotypic ratio: 2 + : 1 ca : 1 e

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. however, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. these global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. in switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. in some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. if these resistant individuals continue to survive and prosper, new resistant populations might emerge. this would be an example of the founder effect artificial selection genetic drift natural selection sexual selection

The negative change found inside the plasma membrane is created by potassium ions sodium ions hydrogen ions chlorine ions

What causes darkening of the skin as melanin production increases