Sickle-cell trait in humans is a classic example of _____. directional selection: a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction; disruptive selection: (or diversifying selection) a mode of natural selection in which extreme values for a trait are favored over intermediate values; stabilizing selection: a type of natural selection in … The different colored snails have the opportunity to interact and breed across the British landscape. Example: Giraffes with the longest necks are able to reach more leaves to each. In the grassy fields, the light-banded snails escape bird predators. After suitable Like directional selection, disruptive selection can be influenced by human interaction. disruptive selection: ... An example of negative frequency-dependent selection can also be seen in the interaction between the human immune system and various infectious microbes such as pathogenic bacteria or viruses. Selective pressures will work in the advantage of the longer neck giraffes and therefore the distribution of the trait within the population will shift towards the longer neck trait. It just favors extreme over normal. There does not appear to be a good example of disruptive selection in human evolution. Figure%: The effect of directional selection on trait distribution Disruptive Selection In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. eration. In stabilizing, the normal trait is favored. In disruptive selection, the normal curve hits extremes and bypasses levels of a trait in the middle. C) disruptive selection. It is the rarest form of selection. The other type of selections wouldnt make any sense to me. In directional, one extreme is favored over the other. Additionally, what are examples of directional selection? Disruptive selection appears to be the rarest form of natural selection and, indeed, there are few well-documented cases of it. Human birth weight is a classic example of the results of: a) genetic drift. An example of directional selection is fossil records that show that the size of the black bears in Europe decreased during interglacial periods of the ice ages, but increased during each glacial period. The occurrence of large or small beak sizes among seed crackers in the absence of medium-sized beaks is an example of A) directional selection B) stabilizing selection C) disruptive selection D) none of the above. d) disruptive selection. The result is a bimodal, or two-peaked, curve in which the … It can be influence by humans. In the darker forest, the dark snails survive and the light-banded snails are eaten. Despite its rarity, however, disruptive selection may be very important for the emergence of species. Key Terms. And this isnt sexual selection . e) stabilizing selection. British land snails are an example of disruptive selection. In this way, human activity resulted in directional selection. Disruptive selection occurs when extreme values of a trait succeed over intermediate values of the same trait, in a given population. I dont believe the definition for disruptive selection favors two or more extremes. Disruptive Selection. b) divergent selection c) directional selection. stabilizing selection.
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