The physical characteristics are called the phenotype; therefore, natural selection works directly on phenotype. The phenotype of an organism is determined by both environmental influences and genotype.

Is natural selection a genotype or phenotype?

The interactions between individuals and their environment is what determines whether their genetic information will be passed on or not. This is why natural selection acts on phenotypes instead of genotypes. A phenotype is an organism's physical traits, while a genotype is an organism's genetic makeup.

How is phenotype related to natural selection?

Natural selection acts on the phenotype, the characteristics of the organism which actually interact with the environment, but the genetic (heritable) basis of any phenotype that gives that phenotype a reproductive advantage may become more common in a population. ... Natural selection is a cornerstone of modern biology.