Evolution in a species is brought about by changes in the gene pool over time, genes being hereditary units which can be passed along to offspring unaltered over time (Colby, 1996). The gene pool is all the genes present in a species or population. The change in frequency of a particular gene in a gene pool can change the characteristics of a population, e.g. a change in the color of moths from light to dark in industrialized areas, as happened in England during the 1800s. As cities became industrialized, there was more soot in the air, and this darkened the trees a certain moth lived on. As this happened, the lighter colored moths were easier for birds to see and prey on, and so few lived to maturity to reproduce. This resulted in a higher proportion of dark colored moths in this species. This is termed natural selection because a particular genetic makeup conferred a survival advantage on the dark colored moths. This is just one example of natural selection.
Dogs, both wild and domestic, come in many shapes and sizes (Natural History Museum, 2002). In the wild, this is due to natural selection. There are over 35 species of wild dogs today, and they live in a range of habitats from the hottest deserts to the arctic wastelands. Each species has different characteristics which allow it to survive in its particular habitat. These characteristics are carried in the genes, and those genes which endow the dog with characteristics which make it suitable to survive in a particular environment become the dominant genes in that population, ensuring survival. For example, the long legs of the maned wolf of the South American pampas allow it to see prey in the tall grass; shunting of blood to their large ears to dissipate excess heat helps the fennec fox survive in the hot deserts; the arctic fox changes its coat from white to brown as the snow melts and it lives on the tundra until the next snowfall, and it has thick fur which...