Evolution works by selecting in favor of the reproduction of some organisms in a population at the expense of other individuals. Natural selection works to eliminate the less inclusively fit from the population, either through death or failure to reproduce, and so drives the gene pool to fit the environment.Continue Reading
Any sizable population of organisms naturally accumulates variations in the genes available to it. Some of the alternative forms of genes in the gene pool confer some advantage to their possessors, which makes the individuals that carry such genes more inclusively fit, or better at meeting the challenges of feeding, escaping predators and reproducing.
Those individuals that happen to be better at living to adulthood and producing offspring naturally contribute a disproportionate number of their genes to the next generation. Genes that consistently aid the survival of the individuals that have them tend to propagate through the population until they achieve fixation.
When a gene becomes fixed, it is found in every individual in the gene pool, which makes it a new species-specific trait. The population can now be said to have evolved slightly. This process works on thousands of genes in the pool, over sometimes millions of years, to keep the population well-suited to its environment.Learn more about Zoology