Evolution – Exam 2 – Study Guide & Revision Notes
genetic drift - ANS ✔✔reduces genetic variation
results from random sampling
faster rate in a small pop (alleles become fixed)
genetic bottleneck - ANS ✔✔cause genetic drift by drastically reducing population size
rare alleles are likely to be lost
ie elephant seals
founder effect - ANS ✔✔a type of genetic drift
random sampling
founding a new population with very few individuals
new population can differ greatly from source pop
ex. organism moving from mainland to island (random allele)
i.e. Huntington diesease brought to SA from Europe
fitness - ANS ✔✔the reproductive success of an individual with a particular phenotype
components: survival to reproductive age, mating success, fecundity
related to NS--not random
compared to other individuals in pop
relative fitness - ANS ✔✔fitness of a genotype standardized by comparison to other genotypes
a specific genotype fitness divided by average fitness of pop
, average excess of fitness - ANS ✔✔difference between average fitness of individuals with allele
vs population average
measure of how much more fitness a trait confers
natural selection vs genetic drift - ANS ✔✔drift is weaker/NS stronger in large popilations
small advantages in fitness can lead to large changes over long term
adaptation - ANS ✔✔a feature that enhances the fitness of a biological entity that possesses it
relative to those that dont
"anything that enhances fitness"
negative selection - ANS ✔✔alleles that lowers fitness
positive selection - ANS ✔✔alleles that increase fitness
additive allele - ANS ✔✔yields twice the phenotypic effect when two copiers are present at a
give locus than occurs when only one copy is present
not influenced by the presence of other alleles (no dominance)
reach fixation in population
directional selection - ANS ✔✔one form is more favored than the other then shift to one
direction or another
variance = same
mean = will go up or down depending
what determines whether an allele becomes fixed in a population? - ANS ✔✔dominance
initial allele frequency
genetic drift - ANS ✔✔reduces genetic variation
results from random sampling
faster rate in a small pop (alleles become fixed)
genetic bottleneck - ANS ✔✔cause genetic drift by drastically reducing population size
rare alleles are likely to be lost
ie elephant seals
founder effect - ANS ✔✔a type of genetic drift
random sampling
founding a new population with very few individuals
new population can differ greatly from source pop
ex. organism moving from mainland to island (random allele)
i.e. Huntington diesease brought to SA from Europe
fitness - ANS ✔✔the reproductive success of an individual with a particular phenotype
components: survival to reproductive age, mating success, fecundity
related to NS--not random
compared to other individuals in pop
relative fitness - ANS ✔✔fitness of a genotype standardized by comparison to other genotypes
a specific genotype fitness divided by average fitness of pop
, average excess of fitness - ANS ✔✔difference between average fitness of individuals with allele
vs population average
measure of how much more fitness a trait confers
natural selection vs genetic drift - ANS ✔✔drift is weaker/NS stronger in large popilations
small advantages in fitness can lead to large changes over long term
adaptation - ANS ✔✔a feature that enhances the fitness of a biological entity that possesses it
relative to those that dont
"anything that enhances fitness"
negative selection - ANS ✔✔alleles that lowers fitness
positive selection - ANS ✔✔alleles that increase fitness
additive allele - ANS ✔✔yields twice the phenotypic effect when two copiers are present at a
give locus than occurs when only one copy is present
not influenced by the presence of other alleles (no dominance)
reach fixation in population
directional selection - ANS ✔✔one form is more favored than the other then shift to one
direction or another
variance = same
mean = will go up or down depending
what determines whether an allele becomes fixed in a population? - ANS ✔✔dominance
initial allele frequency
