Analyze and evaluate how natural selection produces change in populations as opposed to individuals.

Natural selection can be described as a phenomenon in which individuals of a population which are better adapted to survive in an environment are favored by nature as compared to the individuals of the population which lack better characteristics to survive in the environment.

Through natural selection, evolution occurs and the allelic frequency changes over a period of time. The process of evolution as well as change in the allelic frequencies does not occur just by a single individual, rather it is a collective effort which takes a lot of time. Hence, we say that natural selection changes the population and not a single individual.

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.