Kermode bears are white bears that are found in the rainforest on Princess Royal and Gribbell islands along the coast of British Columbia. This subspecies of black bears is known as the Spirit Bear. Its white fur is the result of a single nucleotide replacement in the melanocortin-1 (Mc1r) receptor portion of the gene that leads to the production of adenine instead of guanine. The white fur allele (W) is a recessive allele unique to this subspecies. Dr. Kermit Ritland and his colleagues found that approximately out of a total population of 73 bears on Princess Royal and Gribbell Islands 48 were white (WW). Of the black bears (BB and BW), 12 were homozygous and 13 were heterozygous. The percentage of white bears on the mainland drops off drastically with distance from those islands.
Assuming complete dominance, estimate the observed allele frequencies (maintain 3 significant digits for all calculations) (1pt)?
q =
p =
Thus, for a randomly mating population at equilibrium, the Hardy-Weinberg theorem gives us the genotype frequencies expected for Kermode bears (1pt).
The expected frequency of BB genotypes =
The expected frequency of BW genotypes =
The expected frequency of WW genotypes =
If there is a population of 37 bears on Princess Royal Island, how many would you expect to be black (1pt)?
How many would you expect to be white (1pt)?
You can use the Chi-square statistic to test whether the observed numbers of your BB,
BW, and WW genotypes (your categories) differ from your expected proportions morethan you would expect due to chance. The Chi-square statistic is a probability distributionthat we can use to estimate the probability (âp-valueâ) of finding differences in observedand expected values. If the observed values are very different from the expected values(resulting in a large Chi-square value), we would say there is a low probability (p<0.01)of that difference occurring due to chance alone. This outcome would suggest somemechanism of evolution (drift, natural selection, etc.) is pushing allele frequencies out ofHardy-Weinberg equilibrium. Use the Chi-square calculator to test for differences in your observed numbers of the three genotypes and the expected frequencies on Princess RoyalIsland (using the âfraction expectedâ option) at:https://graphpad.com/quickcalcs/chisquared1.cfm.
Are the observed numbers and expected frequencies significantly different? What doesthis mean is happening to white bears on Princess Royal Island (2pts)?
Kermode bears are white bears that are found in the rainforest on Princess Royal and Gribbell islands along the coast of British Columbia. This subspecies of black bears is known as the Spirit Bear. Its white fur is the result of a single nucleotide replacement in the melanocortin-1 (Mc1r) receptor portion of the gene that leads to the production of adenine instead of guanine. The white fur allele (W) is a recessive allele unique to this subspecies. Dr. Kermit Ritland and his colleagues found that approximately out of a total population of 73 bears on Princess Royal and Gribbell Islands 48 were white (WW). Of the black bears (BB and BW), 12 were homozygous and 13 were heterozygous. The percentage of white bears on the mainland drops off drastically with distance from those islands.
Assuming complete dominance, estimate the observed allele frequencies (maintain 3 significant digits for all calculations) (1pt)?
q =
p =
Thus, for a randomly mating population at equilibrium, the Hardy-Weinberg theorem gives us the genotype frequencies expected for Kermode bears (1pt).
The expected frequency of BB genotypes =
The expected frequency of BW genotypes =
The expected frequency of WW genotypes =
If there is a population of 37 bears on Princess Royal Island, how many would you expect to be black (1pt)?
How many would you expect to be white (1pt)?
You can use the Chi-square statistic to test whether the observed numbers of your BB,
BW, and WW genotypes (your categories) differ from your expected proportions morethan you would expect due to chance. The Chi-square statistic is a probability distributionthat we can use to estimate the probability (âp-valueâ) of finding differences in observedand expected values. If the observed values are very different from the expected values(resulting in a large Chi-square value), we would say there is a low probability (p<0.01)of that difference occurring due to chance alone. This outcome would suggest somemechanism of evolution (drift, natural selection, etc.) is pushing allele frequencies out ofHardy-Weinberg equilibrium. Use the Chi-square calculator to test for differences in your observed numbers of the three genotypes and the expected frequencies on Princess RoyalIsland (using the âfraction expectedâ option) at:https://graphpad.com/quickcalcs/chisquared1.cfm.
Are the observed numbers and expected frequencies significantly different? What doesthis mean is happening to white bears on Princess Royal Island (2pts)?
