Lecture 3.4 - IB 150 Evolutionary Mechanisms 3: Natural
Selection Questions With Complete Solutions
3 components of fitness Correct Answers to leave viable
offspring in the next generation, individuals must:
1. be able to survive until reproductive age
2. find and "acquire" a mate
3. successfully reproduce offspring
4 postulates of natural selection Correct Answers 1. pre-existing
phenotype variation in the population
2. variation is heritable (has a genetic basis)
3. differences in reproductive success among individuals
4. reproductive success depends on this phenotypic trait
A trait can only evolve via natural selection, if ... Correct
Answers it enhances the likelihood of alleles associated with
that trait to be passed on
abitioc Correct Answers temperature, moisture, pH, salinity
Adaptations are traits that evolved via natural selection Correct
Answers ∙ heritable trait that increases the fitness of that
individual organism relative to an organism that does not have
that trait = adaptation
∙ in natural selection, adaptations become more frequent
∙ individuals do not evolve
Are the changes to allele frequencies that result in a population
due to natural selection random, or are they predictible? Correct
Answers allele frequencies change in a predictable manner
, biotic Correct Answers interactions with other organisms such
as predation, competition
common misconceptions about fitness Correct Answers ∙ does
not mean physical fitness
deleterious alleles _____ fitness Correct Answers reduce
deleterious alleles can persist in a population by... Correct
Answers ∙ "hiding" in heterozygous carriers at low frequency
∙ if population is small, may be maintained (or even fixed) due to
drift. in VERY small populations, the effects of drift can
outweigh the effect of selection
∙ gene with deleterious allele may be closely linked to an allele
of a different gene that is under strong positive selection, and
increase in abundance by "hitchhiking" along. this is called
"selective sweep."
∙ fitness associated with deleterious trait may change with
environment
Environment poses _____ _______ on genotypes that
correspond to phenotype with higher reproductive success than
other phenotypes under the prevailing environmental conditions,
leading to these genotypes to have a higher likelihood of passing
their alleles on, and these alleles becoming hence more common
in the gene pool of the next generation. Correct Answers
selection pressures
environmental factors that can act as selection pressures can be
Correct Answers abiotic or biotic
Selection Questions With Complete Solutions
3 components of fitness Correct Answers to leave viable
offspring in the next generation, individuals must:
1. be able to survive until reproductive age
2. find and "acquire" a mate
3. successfully reproduce offspring
4 postulates of natural selection Correct Answers 1. pre-existing
phenotype variation in the population
2. variation is heritable (has a genetic basis)
3. differences in reproductive success among individuals
4. reproductive success depends on this phenotypic trait
A trait can only evolve via natural selection, if ... Correct
Answers it enhances the likelihood of alleles associated with
that trait to be passed on
abitioc Correct Answers temperature, moisture, pH, salinity
Adaptations are traits that evolved via natural selection Correct
Answers ∙ heritable trait that increases the fitness of that
individual organism relative to an organism that does not have
that trait = adaptation
∙ in natural selection, adaptations become more frequent
∙ individuals do not evolve
Are the changes to allele frequencies that result in a population
due to natural selection random, or are they predictible? Correct
Answers allele frequencies change in a predictable manner
, biotic Correct Answers interactions with other organisms such
as predation, competition
common misconceptions about fitness Correct Answers ∙ does
not mean physical fitness
deleterious alleles _____ fitness Correct Answers reduce
deleterious alleles can persist in a population by... Correct
Answers ∙ "hiding" in heterozygous carriers at low frequency
∙ if population is small, may be maintained (or even fixed) due to
drift. in VERY small populations, the effects of drift can
outweigh the effect of selection
∙ gene with deleterious allele may be closely linked to an allele
of a different gene that is under strong positive selection, and
increase in abundance by "hitchhiking" along. this is called
"selective sweep."
∙ fitness associated with deleterious trait may change with
environment
Environment poses _____ _______ on genotypes that
correspond to phenotype with higher reproductive success than
other phenotypes under the prevailing environmental conditions,
leading to these genotypes to have a higher likelihood of passing
their alleles on, and these alleles becoming hence more common
in the gene pool of the next generation. Correct Answers
selection pressures
environmental factors that can act as selection pressures can be
Correct Answers abiotic or biotic
