Gene Pool
The term gene pool refers to the sum total of all the genetic information stored within any given population. A gene is a specific portion of a DNA (deoxyribose nucleic acid) molecule, so a gene pool is the sum total of all of the DNA contained within a population of individuals.
The concept of gene pool is important in ecological studies because it reveals changes that may or may not be taking place within a population. In a population living in an ideal environment for its needs, the gene pool is likely to undergo little or no change. If individuals are able to obtain all the food, water, energy, and other resources they need, they experience relatively little stress and there is no pressure to select one or another characteristic.
Changes do occur in gene frequency because of natural factors in the environment. For example, natural radiation exposure causes changes in DNA molecules that are revealed as genetic changes. These natural mutations are one of the factors that make possible continuous changes in the genetic constitution of a population that, in turn, allows for evolution to occur.
Natural populations seldom live in ideal situations, however, and so they experience various kinds of stress that lead to changes in the gene pool. A classical example of this kind of change was reported by J. B. S. Haldane in 1937. Haldane found that a population of moths gradually became darker in color over time as the trees on which they lived also became darker because of pollution from factories. Moths in the population who carried genes for darker color were better able to survive and reproduce than were their lighter-colored cousins, so the composition of the gene pool changed to relieve stress.
Humans have the ability to make conscious changes in gene pools that no other species has. Sometimes we make those changes in the gene pools of plants or animals to serve our own needs for food or other resource. Hybridization of plants to produce populations that have some desirable quality such as resistance to disease, shorter growing season, or better-tasting fruit. The modern science of genetic engineering is perhaps the most specific and deliberate way of changing in gene pools today.
Humans can also change the gene pool of their own species. For example, individuals with various genetic disorders were at one time doomed to death. Our inability to treat diabetes, sickle-cell anemia, phenylketonuria, and other hereditary conditions meant that the frequency of the genes causing those disorders in the human gene pool was kept under control by natural forces.
Today, many of those same disorders can be treated by medical or genetic techniques. That results in positive benefit for the individuals who are cured, but raises questions about the quality of the human gene pool overall. Instead of having many of those deleterious genes being lost naturally by an individual's death, they are now retained as part of the gene pool. This fact has at times raised questions about the best way in which medical science should deal with genetic disorders.
Agricultural Revolution; Birth Defects; Extinction; Gene Bank; Population Growth
Resources
Books
Patt, D. I., and G. R. Patt. An Introduction to Modern Genetics. Reading, MA: Addison-Wesley, 1976.
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