BIOE 20C Lecture Notes - Lecture 3: Sexual Selection, Sampling Error, Allele Frequency

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blacklion940

7 Oct 2018

School

UCSC

Department

Ecology and Evolutionary Biology

Course

BIOE 20C

Professor

Baldo Marinovic

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Document Summary

Gene: region of dna that codes for a specific polypeptide. Locus: the physical location of a specific gene on a chromosome. Explains why allele frequencies don"t change unless evolution is occuring. Frequencies of all alleles in a population add up to 1 (100%) If you know the frequencies of all alleles in a current generation. You can predict frequencies of the next generation. You can then use genotype frequency to calculate allele frequencies. If frequency of allele = 1 then the allele is fixed. If frequency of allele = 0 then the allele is lost. Genetic diversity is the number and relative frequency of alleles in a population. Lack of genetic diversity usually reduces the ability of the population to respond to environmental change. Occurs when one phenotype has higher fitness. Alleles associated with that phenotype will increase in frequency. Alleles associated with mean trait values favored. No change in average trait value over time.

Related Questions

Q1. What are alleles?Different forms of the same gene.Different genes.The different characteristics of an organism.Genes found only in humans.Q2. If you add up the frequency of homozygotes + the frequency of heterozygotes for one gene (i.e. at one locus) in a population, what number do you get?Q3. People who are heterozygous for the sickle-cell allele:Are susceptible to malaria but not sickle-cell anemia.Are susceptible to sickle-cell anemia but not malaria.Are not susceptible to either sickle-cell anemia or malaria.Are susceptible to both sickle-cecell anemia and malaria.Q4. In the case study in this lab, which genotype is represented by "2pq" in the Hardy-Weinberg equation?Homozygous HbAHomozygous HbSHeterozygous HbA/HbSNo specific genotypeQ5. Suppose that, in an isolated village, the proportion of individuals that have sickle-cell anemia is 0.1 (or 1 of every 10 people). What proportion of the population should be sickle-cell carriers, according to Hardy-Weinberg expectations?Q6. When you simulated the elimination of malaria at the beginning of the lab, once the allele frequencies stabilized, what was the frequency of the HbA allele?Q7. When you investigated regional differences, what was the frequency (over many generations) of the HbS allele in the village in the "slightly wet" part of Africa?Q8. What is the number of deaths due to sickle-cell anemia in a region without mosquitoes expected to be?Very lowVery highModerateRelated to the frequency of malaria allelesQ9. As long as there are multiple alleles of a gene in a population, why will the frequencies of the alleles always change over time?Because natural selection changes all allele frequencies in populations over time.Because genetic drift causes random fluctuations of allele frequencies in populations.Because diseases will eliminate some of the alleles, generating fluctuations in their frequencies.Because allele frequencies fluctuate before the alleles eventually become fixed.Q10. Imagine a huge population with a gene that has ten functionally equivalent, neutral alleles. A small but genetically representative group of individuals from the big population is transported to an island, forming a small population. Which of the statements below best describes what will likely happen over time, and why?Because natural selection doesn't act on neutral alleles, the frequencies in the two populations should remain the same over time.Genetic drift will cause one allele to first become fixed in the island population, and later to become fixed in the original, large population.Genetic drift will result in the allele frequencies of the two populations diverging over time, with alleles being lost sooner in the island population.The allele frequencies of the two populations will change similarly due to a combination of genetic drift natural selection.

indigosnake469

I need this in 15 min!Please help!!!1

A gene in a population of sexually reproducing organisms with the following genotype frequencies is at Hardy-Weinberg Equilibrium: BB 100, Bb 800, bb 100

A) true B)false C) can not be determined

Which of the following evolutionary forces would be the best explanation for the genotype frequencies in the population in the above question?

A) genetic drift B) there are no evolutionary forces acting on this gene population C)assortive mating D) Overdominance E)Directional selection

If a population is at Hardy-Weinberg equilibrium, which of the following allele frequencies would yield the smallest number of heterozygotes? A)

A=0.25, B=0.75 B) A=0.75, B=0.25

C)A=0.50, B=0.50

D)A=0.10, B=0.90

Fixation occurs when one allele becomes the only allele for a gene in a population, meaning that all other alleles for that gene have been lost. True or false

azurepug898

In 1908 Hardy and Weinberg published papers showing that the binomial or multinomial could be applied in genetics to predict the frequencies of genotypes when allele frequencies where known. The formal algebraic proof of this Hardy-Weinberg Equilibrium Law assumes that there is no mutation in the population. This assumption is necessary, because a. organisms reproduce sexually and litter or family sizes vary. b. populations will exhibit random sampling changes in allele frequency. c. populations are not infinite and the Hardy-Weinberg proof is only a very crude approximation when natural selection is acting. d. populations are not closed and reproduce both sexually and asexually so an infinite size population is required to preserve genetic variation. e. allowing alleles to change would alter their frequencies.

amethystcrab894

BIOE 20C Lecture Notes - Lecture 3: Sexual Selection, Sampling Error, Allele Frequency

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