theory of evolution

Evolution as an Adaptation

The Chipping Sparrow is found across most of North America and eats mainly insects an seeds that are found in suburban areas and in farmland in the United States "Chipping Sparrow . Since the early 1990s , the feeding range of the Chipping Sparrow has included farms that grow genetically-modified grains , including the corn and wheat that are part of the Chipping Sparrow 's traditional diet "Genetically Altered Wheat Promises Higher Yields . Genetically-modified seeds are used to develop crops that are resistant to disease or pests , that use less water

, or that are needed for specific requirements such as for pharmaceutical uses . While these crops may be helpful to humans , this change in the food supply could have important implications for the evolution of the Chipping Sparrow and other animals (Chrenkova , Sommer , Ceresnakova , et al , 2002

Although Chipping Sparrows share enough common traits to qualify as a unique species , differences still exist between individual Chipping Sparrows . Some of these differences might include metabolic differences that affect the individual bird 's digestive process . It is possible that the genetically-modified corn , for example , could be missing an enzyme that is essential to the Chipping Sparrow 's digestive process . If this happened , then the majority of Chipping Sparrows would not be able to break down the modified corn and would not benefit from eating it . The birds might feel "full , but an essential part of their diet would be missing . Unless they could find another source of food , these Chipping Sparrows would eventually die of malnutrition

It is also possible that a small number of Chipping Sparrows could have some genetic metabolic abnormality that made it possible for them to digest the modified corn without this particular missing enzyme . In fact , it is even possible that this genetic abnormality in these sparrows ' digestive systems had always existed and that earlier generations of Chipping Sparrows who had this trait tended to have shortened life spans . If this had happened , then this digestive trait would have been passed along , but would only be present in a small number of the sparrows who would have been less likely to reproduce . If this was the case , then the change in the food supply could turn what had been a genetic liability into a genetic benefit . The Chipping Sparrows that could digest the modified corn would survive and would pass this trait along to their offspring . Those that did not have the trait would eventually either die or migrate . The fate of the Chipping Sparrows that remained would not be decided by luck , but would be the result of a genetic mutation that proved to be beneficial in their new environment

The change in the environment would effect the Chipping Sparrow population in stages . First , the majority of Chipping Sparrows that were unable to digest the modified corn would either leave or die , resulting in a severe drop in the Chipping Sparrow population . The sparrows that had the gene for the digestive trait would pass it...