The McDonald-Kreitman test measures this process by comparing the number of fixed differences and polymorphisms of a sequence. Sequences with a high ratio of non-synonymous substitutions over synonymous substitutions may be undergoing the positive type of this process. Kimura and Ohta have claimed the frequency of this process is quite small and argued for a "neutralist" position. George Price generalized Fisher's "fundam
The McDonald-Kreitman test measures this process by comparing the number of fixed differences and polymorphisms of a sequence. Sequences with a high ratio of non-synonymous substitutions over synonymous substitutions may be undergoing the positive type of this process. Kimura and Ohta have claimed the frequency of this process is quite small and argued for a "neutralist" position. George Price generalized Fisher's "fundamental theorem" of this process, which state's an organism's increase in fitness is equal to its genetic variance. This process is non-random, unlike genetic drift or genetic flow, and famous examples include the change in coloration of peppered moths and the development of beak shapes in finches. FTP, name this mechanism of evolution. 
The McDonald-Kreitman test measures this process by comparing the number of fixed differences and polymorphisms of a sequence.
natural selection [accept neutral theory of molecular evolution or neutral mutation theory until end of second sentence, prompt on "evolution" until mentioned]