BIO120H1 Chapter 2: Struggle for Existence Part 2 Summary
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BIO120H1 Full Course Notes
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Evolution of traits are perfected entirely by the trial-and-error of natural selection proposed by. If a feature increases an organism"s ability to survive and pass on its genes, we call the role a function and the feature an adaptation. Some traits may not have a discernable function and these are considered neutral. Some traits may also be considered maladaptive because they reduce fitness. Maladaptive traits are likely to be prominent in a changing environment, where new ecological challenges or opportunities change the fitness consequences of pre-existing characteristics. A good example would be human"s attraction to sweet food high in calories. These maladaptive traits are maintained by tradeoffs and constraints. Critically, natural selection does not act directly upon traits or genes in isolation. Note that nothing in the action of natural selection prevents traits from multitasking. And the adaptive value of the trait will depend on its overall effect on the organism, through all of its functions.
