Lombard, Jazmine A comprehensive introduction to selection (important process in evolution). University Publications, Delhi, India. ISBN 9788132336921
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Abstract
In the context of evolution, certain traits or alleles of genes segregating within a population may be subject to selection. Under selection, individuals with advantageous or “adaptive” traits tend to be more successful reproductively than their peers—meaning they contribute more offspring to the succeeding generation than others do. When these traits have a genetic basis, selection can increase the prevalence of those traits, because offspring will inherit those traits from their parents. When selection is intense and persistent, adaptive traits become universal to the population or species, which may then be said to have evolved. Whether or not selection takes place depends on the conditions in which the individuals of a species find themselves. Adults, juveniles, embryos, and even eggs and sperm may undergo selection. Factors fostering selection include limits on resources (nourishment, habitat space, mates) and the existence of threats (predators, disease, adverse weather). Biologists often refer to such factors as selective pressures. Natural selection is the most familiar type of selection by name. The breeding of dogs, cows and horses, however, represents "artificial selection". Subcategories of natural selection are also sometimes distinguished. These include sexual selection, ecological selection, stabilizing selection, disruptive selection and directional selection (more on these below). Selection occurs only when the individuals of a population are diverse in their characteristics or more specifically when the traits of individuals differ with respect to how well they equip them to survive or exploit a particular pressure. In the absence of individual variation, or when variations are selectively neutral, selection does not occur. Meanwhile, selection does not guarantee that advantageous traits or alleles will become prevalent within a population. Through genetic drift, such traits may become less common or disappear. In the face of selection even a so-called deleterious allele may become universal to the members of a species. This is a risk primarily in the case of populations "weak" selection (e.g an infectious disease with only a low mortality rate) or small population.
| Item Type: | Book |
|---|---|
| Subjects: | Q Science > QH Natural history |
| Depositing User: | Esam @ Hisham Muhammad |
| Date Deposited: | 12 Feb 2023 06:48 |
| Last Modified: | 12 Feb 2023 06:48 |
| URI: | http://odlsystem2.utm.my/id/eprint/3986 |
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