Related to evolution, how do environmental changes (bigand small) affect a popul
ID: 2977 • Letter: R
Question
Related to evolution, how do environmental changes (bigand small) affect a population over generations? a. For example, changes can be global warming, in or out flux ofpredators, change in vegetation, or use of pesticides as starters. Any more? b.How does their size, color get affected? Related to evolution, how do environmental changes (bigand small) affect a population over generations? a. For example, changes can be global warming, in or out flux ofpredators, change in vegetation, or use of pesticides as starters. Any more? b.How does their size, color get affected?Explanation / Answer
a. Natural disasters can be responsible, as it will create apopulation bottleneck, because only the survivors' genes will bepassed on. Ice ages are another big factor (e.g., species inaffected areas during ice ages were adapted to the cold). I don't think the use of pesticides is an environmental change inthe sense that global warming is, as it is created by mankind. b. Changes in size and color tend to vary, depending on the factorsthat created the change. Examples of variations in color: There was a species of moths that lived on the gray barks oftrees. Black individuals had the tendency to be eaten, asthey stood out on the pale bark. As a result, mostindividuals in that population were white. However, when coalsmoke blackened the trees bark, the white individuals became morevisible to predators, and black wings became more prevalent in thepopulation. When clean industry in the area was developed andthe bark turned light again, the population once again favoredwhite moths. Another example of variation in color is the humanpopulation. People who live in sunny areas tend to havedarker skin, as the melanin helps prevent them from developingsunburns and melanoma. If areas without a lot of sunlightsuddenly experienced more solar radiation, evolution would favorthose with dark skin and not those with fair skin. Variations in size: This one is tricky. Large individuals tend to survive betterin cold climates, as they are more insulated from the cold (smallerindividuals lose heat more rapidly), while smaller individuals tendto thrive more in hotter areas (provided that there is enough waterpresent; small individuals are also prone to dehydration). For example, famines in human populations are often caused by coldperiods (e.g. the volcanic eruption that resulted in the yearwithout a summer in which many people starved), so a drop intemperature could cause evolutionary change favoring largerindividuals with larger fat stores, which would make them lesslikely to starve and more able to insulate their bodies from thecold. This is a tough question, but I hope I helped!