ANSC446 Exam 2 Questions with 100% Correct
Answers
Natural selection
process by which favorable heritable traits become more common in successive generations of a
population
relative fitness
relative ability of different genotypes to pass on their alleles to future generations
homozygote lethal
phenotype results in early death
- glued in drosophila melanogaster
heterozygote advantage/over dominance
both homozygotes have selective disadvantage over heterozygous genotype
- rodent warfarin resistance
-sickle cell anemia
-Major histocompatibility complex
heterozygote disadvantage/underdominance
both homozygotes have selective advantage over heterozygous advantage
- Rh factor
Fishers fundamental theorem of natural selection
, the rate of increase in fitness of any organism at any time is equal to its genetic variance in
fitness at that time
Selection coefficient
measures
the amount of selection against a
homozygote
The level of dominance
when
multiplied by s measures the amount
of selection against the heterozygote
Purifying selection
focus is on
reduction in frequency of detrimental
allele A2. Allele that is lethal has s=1,
fitness of 0. Detrimental alleles, s may
be from 0 to 1, fitness from 1 to 0
Adaptive or positive Darwinian
selection:
focus is on increase in
frequency of beneficial allele A1
Answers
Natural selection
process by which favorable heritable traits become more common in successive generations of a
population
relative fitness
relative ability of different genotypes to pass on their alleles to future generations
homozygote lethal
phenotype results in early death
- glued in drosophila melanogaster
heterozygote advantage/over dominance
both homozygotes have selective disadvantage over heterozygous genotype
- rodent warfarin resistance
-sickle cell anemia
-Major histocompatibility complex
heterozygote disadvantage/underdominance
both homozygotes have selective advantage over heterozygous advantage
- Rh factor
Fishers fundamental theorem of natural selection
, the rate of increase in fitness of any organism at any time is equal to its genetic variance in
fitness at that time
Selection coefficient
measures
the amount of selection against a
homozygote
The level of dominance
when
multiplied by s measures the amount
of selection against the heterozygote
Purifying selection
focus is on
reduction in frequency of detrimental
allele A2. Allele that is lethal has s=1,
fitness of 0. Detrimental alleles, s may
be from 0 to 1, fitness from 1 to 0
Adaptive or positive Darwinian
selection:
focus is on increase in
frequency of beneficial allele A1
