What is true about traits and adaptations? Select all the true sentences.
Answers
Answer:
Explanation:
Positive natural selection, or the tendency of beneficial traits to increase in prevalence (frequency) in a population, is the driving force behind adaptive evolution. For a trait to undergo positive selection, it must have two characteristics. First, the trait must be beneficial; in other words, it must increase the organism's probability of surviving and reproducing. Second, the trait must be heritable so that it can be passed to an organism's offspring. Beneficial traits are extremely varied and may include anything from protective coloration, to the ability to utilize a new food source, to a change in size or shape that might be useful in a particular environment. If a trait results in more offspring who share the trait, then that trait is more likely to become common in the population than a trait that arises randomly. At the molecular level, selection occurs when a particular DNA variant becomes more common because of its effect on the organisms that carry it.
Charles Darwin and Alfred Wallace (1858) famously proposed that positive selection could explain the many marvelous adaptations that suit organisms to their environments and lifestyles, and this simple process remains the central explanation for all evolutionary adaptation yet today. Positive selection is by no means the only component of evolution, however. In humans, at least, the great majority of mutations are thought to be selectively neutral, conferring neither benefit nor cost on their bearers (Hellmann et al., 2003). The frequency of some of these neutral genetic variants (alleles) increases simply by chance, and the resulting "genetic drift" is thought to be the most common process in human evolution (Kimura, 1968). Moreover, when selection does occur, it is most often in the form of negative, or purifying, selection, which removes new deleterious mutations as they arise, rather than promoting the spread of new traits (Kreitman, 2000).