Exam 2 Flashcards
The fact that the mtDNA of all living humans traces back to a single female ancestor is largelythe result of which evolutionary process?
genetic drift
What is true about bipedalism in early hominids?
Bipedalism evolved before brain size and when the species was in woodlands.
A gene locus has two alleles (A & B). If the three genotypes have the same phenotype:
All genotypes have relative fitness equal to 1.
Low genetic effective population size (Ne) will:
Increase the impact of genetic drift.
- For genetic drift to have a strong impact on change in allele frequency at a gene locus which of the following must be true:
Natural selection must have little impact, gene flow must be low or absent, and the genetic effective population must be small.
The impact of maternal environmental effects on offspring phenotype occurs as a result of:
The provisioning of the egg by the mother.
F(A) vs. Generation graph: negative, exponential decay
The “A” allele is deleterious and has completely recessive effects on fitness.
F(A) vs. Generation graph: reversed S shape
The “A” allele is deleterious with additive effects on fitness.
F(A) vs. Generation graph: S, with a plateau at the top
The “A” allele is beneficial with completely dominant effects on fitness
F(A) vs. Generation graph: S with plateau around the middle
AA > AB > BB
F(A) vs. Generation graph: S, with a plateau at the top
AA > AB = BB
F(A) vs. Generation graph: strong divergence of both alleles
BB > AA > AB
What is correct about the impact of genetic drift and inbreeding on heterozygosity (H), polymorphism (P), and allelic richness (A) in a population:
Genetic drift decreases H, P and A while inbreeding only decreases H.
Dominant alleles usually occur at higher frequencies than do recessive alleles. Beneficial alleles are usually dominant. Dominant alleles are usually beneficial. An allele that confers high fitness will be at high frequency.
All four of these statements are false.
After an experiment, two populations, M and N, have allele frequencies at 1:
This is a product of genetic drift and selection for M
This mating behavior (Storz et al 2001) results in some males fathering many pups and other males failing to form harems and reproduce. This will have which of the following effects:
It will decrease effective population size because of the high variance in male family
size.
Bees and elderflowers…
Negative frequency dependent selection because, fluctuating because high frequency tricksters are known to be deceptive.
What could result in heterozygote deficiency?
Inbreeding or heterozygote disadvantage; also genetic drift
Fst: Species X lives in small, isolated populations; very few individuals move among populations…
Expect FST to be high. These are small population that will be strongly impacted by genetic drift, which results in the loss of alleles and increased fixation and differentiation among populations. There is little gene flow to counteract drift, and the alleles are neutral so natural selection is not occurring.
Species Y lives in small populations, and movement of individuals among populations is common…
Expect FST to be low to low/moderate. While the small populations may be strongly impacted by genetic drift the movement of individuals produces gene flow. Gene flow decreases the chance of fixation and differentiation by homogenizing populations. Gene flow will almost certainly offset most or all impacts of genetic drift.
Species Z lives in large populations, and there is moderate movement of individuals among populations…
Expect FST to be very low. Genetic drift won’t have much impact in these large populations and gene flow will further decrease the chance for fixation and differentiation of populations.
Explain the impact of gene flow and natural selection on the pattern of copper
tolerance at the mine site.
High selection for copper tolerance, but low prevalence because of gene flow.
Explain the impact of gene flow and natural selection on the pattern of copper
tolerance at the 5 mile site.
Gene flow is acting counter to local adaptation.
