Three types of natural selection Classify each description according to the type
ID: 45207 • Letter: T
Question
Three types of natural selection Classify each description according to the type of natural selection it describes. Natural selection selects two occurs when population is Natural selection favors Natural selection favors or more extreme phenotypes adapting to a changing extreme phenotypes over the intermediate phenotypes over over any intermediate environment intermediate phenotypes the extreme phenotypes phenotypes The distribution curve shifts in Improves adaptation of the Promotes distinct phenotypes the direction of a single population to constant aspects within a population extreme phenotype of the environment Stabilizing selection Directional selection Disruptive selection Initial Distribution Initia nitia Distribution E Distribution Banding Pattern Clutch Size Body Size After Time After After Time Time Banding Pattern Clutch Size Body Size After More Time After After More Time More Time Clutch Size Banding PatternExplanation / Answer
Disruptive- Natural selection selects two or more extreme phenotypes over any intermediate phenotypes.
When selective pressures select against the two extremes of a trait, the population experiences stabilizing selection. For example, plant height might be acted on by stabilizing selection. A plant that is too short may not be able to compete with other plants for sunlight. However, extremely tall plants may be more susceptible to wind damage. Combined, these two selection pressures select to maintain plants of medium height. The number of plants of medium height will increase while the numbers of short and tall plants will decrease.
In directional selection, one extreme of the trait distribution experiences selection against it. The result is that the population's trait distribution shifts toward the other extreme. In the case of such selection, the mean of the population graph shifts. Using the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed. As a result, the distribution of neck length shifted to favor individuals with long necks.
In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. The result is a bimodal, or two-peaked, curve in which the two extremes of the curve create their own smaller curves. For example, imagine a plant of extremely variable height that is pollinated by three different pollinators, one that was attracted to short plants, another that preferred plants of medium height and a third that visited only the tallest plants. If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants. Such a population, in which multiple distinct forms or morphs exist is said to be polymorphic.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.