BIO3122 Midterm 2 lectures 7-12 Questions With Complete
Solutions
Anisogamy Correct Answers Refers to a difference in gamete
size in males and females. Eggs large and costly, sperm small
and cheap
consequences of genetic drift Correct Answers - Allele
frequencies fluctuate at random within a population over time
- If only genetic drift is acting on alleles within a population,
one allele at each locus will eventually be fixed (frequency = 1),
all others will be lost (frequency = 0)...just by chance!
- Chance acts on good, bad, and neutral alleles alike
- Key point: drift can lead to the loss of beneficial alleles or the
fixation of deleterious alleles
- And this is occurring across the genome: Drift operates on all
loci in the genome
Consequences of sexual reproduction Correct Answers
anisogamy
- cost of choosing bad mate
- availability of receptive mates
- choice vs competition of mates
- variance in reproductive success
Costs of finding and attracting a mate Correct Answers
Costs of meiosis Correct Answers Asexual individuals pass on
their entire genotype (100% of their alleles) whereas sexually
reproducing individuals only pass on one half of their alleles
, Meiosis also breaks apart favourable allele combinations!
Dispersal Correct Answers The permanent movement of
individuals between breeding populations
- From a pure numbers, standpoint, dispersal can affect
population size (think about the consequences for evolution
based on the processes we've discussed so far)
Movement of individuals away from centers of high population
density or their area of origin.
empirical evidence Correct Answers In asexual populations of
yeast, deleterious mutations often fixed with beneficial
mutations.
In sexual populations, beneficial mutations fixed by selection
while deleterious mutations purged.
Example of consequence of genetic drift Correct Answers Buri
(1956) followed 107 replicate Drosophila populations that each
started with 16 heterozygotes for two alleles that govern eye
colour in a co-dominant fashion
Initial p = 0.5
He randomly selected individuals to breed each generation
Over time, most populations had fixed one allele or the other
Solutions
Anisogamy Correct Answers Refers to a difference in gamete
size in males and females. Eggs large and costly, sperm small
and cheap
consequences of genetic drift Correct Answers - Allele
frequencies fluctuate at random within a population over time
- If only genetic drift is acting on alleles within a population,
one allele at each locus will eventually be fixed (frequency = 1),
all others will be lost (frequency = 0)...just by chance!
- Chance acts on good, bad, and neutral alleles alike
- Key point: drift can lead to the loss of beneficial alleles or the
fixation of deleterious alleles
- And this is occurring across the genome: Drift operates on all
loci in the genome
Consequences of sexual reproduction Correct Answers
anisogamy
- cost of choosing bad mate
- availability of receptive mates
- choice vs competition of mates
- variance in reproductive success
Costs of finding and attracting a mate Correct Answers
Costs of meiosis Correct Answers Asexual individuals pass on
their entire genotype (100% of their alleles) whereas sexually
reproducing individuals only pass on one half of their alleles
, Meiosis also breaks apart favourable allele combinations!
Dispersal Correct Answers The permanent movement of
individuals between breeding populations
- From a pure numbers, standpoint, dispersal can affect
population size (think about the consequences for evolution
based on the processes we've discussed so far)
Movement of individuals away from centers of high population
density or their area of origin.
empirical evidence Correct Answers In asexual populations of
yeast, deleterious mutations often fixed with beneficial
mutations.
In sexual populations, beneficial mutations fixed by selection
while deleterious mutations purged.
Example of consequence of genetic drift Correct Answers Buri
(1956) followed 107 replicate Drosophila populations that each
started with 16 heterozygotes for two alleles that govern eye
colour in a co-dominant fashion
Initial p = 0.5
He randomly selected individuals to breed each generation
Over time, most populations had fixed one allele or the other
