A researcher is interested to test the hypothesis that a 100 base pair stretch of a given gene is under selection
She sequences this gene region in 30 individuals, each of two populations. She finds that within either popula-tion, there are 33 synonymous sites of which 10 are segregating for different alleles in the population. In this same sequence, she observes 29 sites within-populations that possess variable alleles at nonsynonymous sites. In contrast, when she compares substitutions across species, she finds that of the 33 synonymous sites only five show signs of a substitution between species. Only 15 nonsynonymous substitutions were observed between species. This suggests that the gene is:
a. under purifying selection.
b. under nearly neutral selection.
c. under positive selection.
d. under directional selection.
e. This cannot be determined based on the information provided.
B
You might also like to view...
Which of the following statements are true regarding the secondary immune response? Select all correct choices
A. It occurs more slowly than the primary immune response. B. It occurs faster than the primary immune response. C. It produces more antibodies than the primary immune response. D. It produces fewer antibodies than the primary immune response.
Which of these is an advantage of reproduction by seed?
a. New plants can absorb nutrients from parent plants during periods of drought and disease. b. New plants can grow in biomes where water and sunlight are absent. c. New plants can grow in areas without competing with their parents for resources. d. Seeds discourage herbivores from grazing on young plants while they develop and grow.
In a human kidney, what is the function of the nephrons?
a. Forming urine b. Sending urine to the ureter c. Collecting urine d. Signaling the urge to urinate
Cells can be large if they
A. are metabolically very active. B. have metabolically inactive central regions. C. actively pump nutrients into the cell. D. have a very small surface area compared to their volume.