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Exam 20: Mechanisms of Evolution

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Question 81

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The survivorship of individuals from four different populations of a beetle species has been assayed and is presented in the table.TT, TC, and CC represent genotypes at a locus that is important in survival. Assuming that genotypes at this locus have no other effects on fitness, would we expect variation to be maintained by selection in any of the populations? Why? What would be the expected outcomes in the populations in the absence of any other evolutionary processes?

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Because the heterozygotes have the highe...

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Question 82

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Diversifying selection is operating on size in a species of barnacles.This means that _______ have the highest fitness and that the variation should _______ over time if size is heritable and if no other forces are operating.

A) only the largest; increase
B) only the largest; decrease
C) only the smallest; increase
D) the largest and the smallest; increase
E) the largest and the smallest; decrease

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Question 83

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Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. Assuming the mutation rate remains the same and mutations accumulate linearly, about how many mutations should there be in strain A after 50 generations?

Suppose that a particular species of flowering plant that lives only one year can produce red, pink, or white blossoms, depending on its genotype: AA, Aa, and aa produce, respectively, red, pink, and white blossoms.Biologists studying a population of this species count 300 red-flowering, 600 pink-flowering, and 800 white-flowering plants.In a census in the same area the following year, biologists find a population with 600 red-flowering, 900 pink-flowering, and 1,000 white-flowering plants.Which color has the highest fitness?

If the effective rate of reproduction of an asexual lineage is 6 per year, what would be the effective rate of reproduction of a lineage that was identical to the asexual lineage in every way, except that it was sexual?

A population of ocotillo plants has four alleles at the Dopa locus, with allelic frequencies of 0.38, 0.32, 0.19, and 0.11, and the genotype frequencies are roughly consistent with the Hardy-Weinberg equilibrium.This is a description of the genetic _______ of the population.

In a population of 800 wolves, 320 are CC and 360 are Cc for a locus with two alleles.Which statement is true?

According to its scientific definition, a theory is

Deviations from Hardy-Weinberg

In the northern regions of its range, a species of bird experiences selection for increased size.Farther south, it experiences selection for decreased size.Given some migration across its range, the most likely result is

Yeast cells are sequenced periodically to examine them for new mutations.The table shows the results. What is the approximate mutation rate per generation for strain A?

Suppose individual robins with longer beaks have somewhat more offspring than those with shorter beaks and this has led to increases in beak length over time.We can say that beak size is associated with the _______ of the robin and that there is _______ selection operating on beak size.

Following is a list of loci of a mustard plant and the frequencies of their most common allele, at different points along geographic distances from a minefield. In which is there evidence of a cline?

The numbers of fledged young from female robins of different sizes were assayed and are presented in the table. Assume that body size is at least partially heritable.Assuming that all other fitness aspects (survival, etc.) are independent of size, this population is most likely experiencing ______ selection, and the population should _______ in size over many generations.

Male earwigs that are DD at a locus have greater success in mating than those that are Dd or dd.Which statement is correct?

If a population is monomorphic for an allele at one locus, the population is _______ for that allele, and the frequency of the allele is _______.

Three different alleles (b1, b2, and b3) at the b locus exist in a hypothetical population of juniper trees.If the frequency of b1 is 0.4, what can be said about the frequency of b3?

A sparrow population currently eats seeds that are mostly of medium size.Which condition will most likely lead to more diversifying selection?

A1 and A2 are different forms of the same gene.These are thus different

The frequency of an allele in a population of Drosophila melanogaster changes haphazardly over time, sometimes going up and sometimes going down.In this population, 17 percent had the allele in 1998 and 30 percent had it in 2016.Biologists found no effect of this allele (versus the other alleles in the population) on any phenotypic trait.What is the best explanation for this pattern?