How does natural selection lead to evolution?

There are limited resources within an environment. There is also variety amongst the individuals within a population. Some varieties are more advantageous within a given environment than others. Therefore, the individuals that possess the characteristics that are less advantageous to the environment will be more likely to perish. Likewise, the individuals that possess the more advantageous variations will be better adapted to their environments. Such individuals will be more likely to obtain the limited resources and survive in that particular environment. As a result, the survivors will have more opportunities to produce offspring. Over time, the genes of the survivors will become more prevalent within the gene pool of the population. As time passes, the results will accumulate and eventually the characteristics of the species change as only some genes are passed on to the next generation year after year. In this way, natural selection leads to evolution.