A species of hummingbird feeds on nectar of a particular plant whose flowers form a long, skinny cup. Beak length is a heritable trait that varies among individual hummingbirds. The birds' beaks must be long enough to reach the nectar, but longer beaks are also heavier and make flying more costly in terms of energy. a. Which mode of selection is this hummingbird species experiencing? b. How does this mode of selection affect the mean and standard deviation over time?

A species of hummingbird feeds on nectar of a particular plant whose flowers form a long, skinny cup. Beak length is a heritable trait that varies among individual hummingbirds. The birds' beaks must be long enough to reach the nectar, but longer beaks are also heavier and make flying more costly in terms of energy. a. Which mode of selection is this hummingbird species experiencing? b. How does this mode of selection affect the mean and standard deviation over time?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter19: Population Genetics And Human Evolution

Section: Chapter Questions

Problem 8QP: How Can We Measure Allele Frequencies in Populations? In a population where the females have the...

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In the garden shed belonging to one of this text’s authors, stabilizing selection has occurred over the past 10 years in the house mouse, Mus musculus. Which of the following scenarios is an example of stabilizing selection? (a) Small and medium-sized mice cannot reach the seed shelf in the shed and therefore are at a disadvantage for ﬁnding food, so they do not survive and reproduce as well as large mice do.(b) Small mice cannot reach the seed shelf, and large mice are easily seen by hawks circling above. Medium-sized mice therefore survive and reproduce better than both small and large mice. (c) Small mice can easily cross the yard to the vegetable garden, and large mice can easily reach the seed shelf. Medium-sized mice have trouble with the seed shelf and are seen by hawks in the yard. Small and large mice survive and reproduce much better than medium-sized mice. (d) All of these are examples of stabilizing selection. (e) None of these are examples of stabilizing selection.
When we take, say, 100 individuals of a species of beetle from the wild and place them in a new environment that is not so different that they are unable to thrive but different enough so that they are experiencing a new selective regime, say, a lower temperature, what typically happens? A - Sexual selection causes some larvae to be able to survive in the cooler temperatures and other individuals to be unable to survive because they need warmer temperatures. B - We are unable to measure phenotypic selection, presumably because we do not have much variation among individuals for how they handle temperature. C - The founder event assures us that the new population will be strictly representative of the source population (especially if we took all the 100 from the same location rather that from throughout the range of the species). D - The population evolves to be tolerant of the lower temperature; it can do this because of latent variation already in the 100 founding individuals. E -…
Which statement best summarizes why genetic drift tends to impact small populations more than large populations? A. Small populations have a heterozygote advantage because heterozygotes are more common than homozygotes. B. Small populations have a smaller gene pool, so random changes influence them more. C. Small populations have a relatively large gene pool, so the founder effect stabilizes their alleles.D. Small populations tend to experience directional selection, making one phenotype more common.
Is each of the following examples due to directional, disruptive, balancing, or stabilizing selection? A. Polymorphisms in snail color and banding pattern as described. B. Thick fur among mammals exposed to cold climates C. Birth weight in humans D. Sturdy stems and leaves among plants exposed to windy climates
A farmer performs truncation selection to try to increase the weight of peaches in his orchard. Which statement correctly describes a possible outcome of this selection? a) If peach weight is not heritable, the average weight in the next generation will increase. b) If peach weight is heritable, the average weight in the next generation will increase. c) The average peach weight will decrease due to this inbreeding. If peach weight is heritable, the average weight in the next generation will decrease.
How Can We Measure Allele Frequencies in Populations? In a population where the females have the allelic frequencies A = 0.35 and a = 0.65 and the frequencies for males are A = 0.1 and a = 0.9, how many generations will it take to reach HardyWeinberg equilibrium for both the allelic and the genotypic frequencies? Assume random mating and show the allelic and genotypic frequencies for each generation.
Consider a hypothetical beetle whose back abdomen pattern is determined by two alleles A1 and A2. Beetles that are homozygous for the 'A1' allele have solid coloring, beetles that are heterozygous (A1A2) are spotted, and beetles that are homozygous for the A2 allele are striped. You find a population of 100 of these beetles and count each phenotype (shown below). TRUE or FALSE: this population is in Hardy-Weinberg equilibrium? What is the predicted frequency of spotted beetle? Solid Beetles = 49 Spotted Beetles = 35 Striped Beetles = 16 asap please
A) Explain why we use the concept of Hardy-Weinberg Equilibrium if populations are never stable? B) What do the mathematical results tell us if the allele frequencies do not match our predictions? (In other words, if you have extra spotted fish in a generation, what has happened?)
Consider a set of genotypes with fitnesses: AA = 1.12 Aa = 1.04 aa = 1.0 Where the frequency of the "A" allele is 0.4. A. What is delta p, the change in the allele frequency to the next generation? B. What is the new frequency of the "A" allele after one generation of selection? (Note: provide both values to the nearest 0.0001)
A. What does it mean if an allele is “fixed”? B. Explain one reason why EVEN if an allele is undergoing strong positive selection it may not become fixed in the population.
The protruding tusk on a narwhal is an enlarged tooth with sensory capabilities. Narwhals are related to other whales. The extreme phenotype of the tusk demonstrates which type of selection? A)Convergent B)Stabilizing C)Directional
If a quantitative trait (egg weight in Chinook salmon) has an h2 of 0.20, and you selected for small eggs by breeding only the small egg producing Chinook salmon (mean egg weight 0.2 grams) in a population with a mean egg weight of 0.35 grams, by how much will the next generation mean eggs weight change?