PCB 4674: Exam 2
Study online at https://quizlet.com/_7c6ekn
1. Migration (gene flow): ________________ reduces differentiation among populations
2. Gene flow: Movement of alleles into or out of a population due to the migration of individuals to or from the
population
3. genetic drift: One individual migrating into a population per generation is enough to prevent
______________ __________ between two populations despite population size
4. Homogenization: A trend toward uniformity, a consequence of gene flow
5. Clines: Gradual shift in gene frequencies between neighboring populations; natural selection steepens and
migration smooths out; consequence of gene flow
6. speciation: Disruption of gene flow is usually a requirement for ______________________
7. intermediate equilibrium: When migration counteracts natural selection, a(n) __________________
_________________ is reached between the two processes
8. Breeding behavior: __________________ _________________ and population structure can reduce
effective population size
9. Nonrandom mating: __________________ ____________ distorts Hardy-Weinburg equilibrium but
does not itself change allele frequencies
10. Inbreeding: ______________________ usually reduces the fitness of offspring and numerous mechanisms
have evolved to prevent it
11. Polyandry: Population structure with one female and several males
12. Polygyny: Population structure with one male and several females
13. Unequal fecundity: Population structure where there is a difference between individuals ability to produce
an abundance of offspring or new growth
14. Unequal mating success: Population structure where there is a difference between the ability of
individuals to successfully mate
15. Effective population size: The average number of individuals in a population that contribute genes
equally to the next generation. Usually smaller than the actual population size due to not all individuals reproducing
creating a skewed sex ratio
Ne = (4NmNf)/(Nm + Nf)
16. Nonrandom mating: Occurs when organisms are more or less likely to mate with others of their
genotypes than by chance, *the probability of an individual mating is determined by both the properties of the individual
and the genotype of the potential mate*; Mating among individuals on the basis of their phenotypic similarities or
differences, rather than mating on a random basis
1/8
, PCB 4674: Exam 2
Study online at https://quizlet.com/_7c6ekn
17. F: The inbreeding coefficient; a measure of population subdivision and the propensity to genetic drift
18. Inbreeding coefficient (F): Refers to the probability that the two alleles at any locus in an individual
will be identical because of common descent; ranges from 0 (random mating, H-W equilibrium) to 0.5 (selfing, which
results in all homozygotes)
19. Heterozygosity (as it relates to F): HF = H0(1-F)
Relates inbreeding to the number of heterozygotes
20. heterozygotes: Inbreeding reduces the number of ___________________ in a population
21. Genetic drift: _____________________ ______________ mimics the effects of long-term inbreeding be-
cause it increases the probability of identity by descent
22. large population: A ____________ ______________ can mimic the effects of inbreeding since alleles can
be identical by descent even if there is random mating in small populations
23. 3 ways to reduce effective population size: Mating system, population subdivision, and
interbreeding
24. phenotypic variation; genetic variation: Inbreeding temporarily increases
_________________ __________________. But over the long term decreases the _________________
________________ by reducing population size (making genetic drift stronger)
25. Deleterious recessives: Alleles that cause a decrease in fitness and are exposed more frequently in
homozygotes
26. Inbreeding depression: The negative reproductive consequences for a population associated with
having a high frequency of homozygous individuals possessing harmful recessive alleles; Occurs when individuals with
similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to
survive and reproduce
27. Mate choice: A form of avoiding inbreeding depression; Determined by a number of factors, including
genetic qualities, overall health, and potential parenting skills of prospective mates; Animals can detect close relatives
and choose not to breed with them
28. Dispersal: A form of avoiding inbreeding depression; Key mechanism to move gametes away from parent
organism; Includes the movement of the organisms as well
29. Self-incompatibility: A form of avoiding inbreeding depression; The ability of a seed plant to reject its own
pollen and sometimes the pollen of closely related individuals to prevent selfing
30. Dioecy: A form of avoiding inbreeding depression; Organisms are separated into two sexes to avoid selfing
2/8
Study online at https://quizlet.com/_7c6ekn
1. Migration (gene flow): ________________ reduces differentiation among populations
2. Gene flow: Movement of alleles into or out of a population due to the migration of individuals to or from the
population
3. genetic drift: One individual migrating into a population per generation is enough to prevent
______________ __________ between two populations despite population size
4. Homogenization: A trend toward uniformity, a consequence of gene flow
5. Clines: Gradual shift in gene frequencies between neighboring populations; natural selection steepens and
migration smooths out; consequence of gene flow
6. speciation: Disruption of gene flow is usually a requirement for ______________________
7. intermediate equilibrium: When migration counteracts natural selection, a(n) __________________
_________________ is reached between the two processes
8. Breeding behavior: __________________ _________________ and population structure can reduce
effective population size
9. Nonrandom mating: __________________ ____________ distorts Hardy-Weinburg equilibrium but
does not itself change allele frequencies
10. Inbreeding: ______________________ usually reduces the fitness of offspring and numerous mechanisms
have evolved to prevent it
11. Polyandry: Population structure with one female and several males
12. Polygyny: Population structure with one male and several females
13. Unequal fecundity: Population structure where there is a difference between individuals ability to produce
an abundance of offspring or new growth
14. Unequal mating success: Population structure where there is a difference between the ability of
individuals to successfully mate
15. Effective population size: The average number of individuals in a population that contribute genes
equally to the next generation. Usually smaller than the actual population size due to not all individuals reproducing
creating a skewed sex ratio
Ne = (4NmNf)/(Nm + Nf)
16. Nonrandom mating: Occurs when organisms are more or less likely to mate with others of their
genotypes than by chance, *the probability of an individual mating is determined by both the properties of the individual
and the genotype of the potential mate*; Mating among individuals on the basis of their phenotypic similarities or
differences, rather than mating on a random basis
1/8
, PCB 4674: Exam 2
Study online at https://quizlet.com/_7c6ekn
17. F: The inbreeding coefficient; a measure of population subdivision and the propensity to genetic drift
18. Inbreeding coefficient (F): Refers to the probability that the two alleles at any locus in an individual
will be identical because of common descent; ranges from 0 (random mating, H-W equilibrium) to 0.5 (selfing, which
results in all homozygotes)
19. Heterozygosity (as it relates to F): HF = H0(1-F)
Relates inbreeding to the number of heterozygotes
20. heterozygotes: Inbreeding reduces the number of ___________________ in a population
21. Genetic drift: _____________________ ______________ mimics the effects of long-term inbreeding be-
cause it increases the probability of identity by descent
22. large population: A ____________ ______________ can mimic the effects of inbreeding since alleles can
be identical by descent even if there is random mating in small populations
23. 3 ways to reduce effective population size: Mating system, population subdivision, and
interbreeding
24. phenotypic variation; genetic variation: Inbreeding temporarily increases
_________________ __________________. But over the long term decreases the _________________
________________ by reducing population size (making genetic drift stronger)
25. Deleterious recessives: Alleles that cause a decrease in fitness and are exposed more frequently in
homozygotes
26. Inbreeding depression: The negative reproductive consequences for a population associated with
having a high frequency of homozygous individuals possessing harmful recessive alleles; Occurs when individuals with
similar genotypes - typically relatives - breed with each other and produce offspring that have an impaired ability to
survive and reproduce
27. Mate choice: A form of avoiding inbreeding depression; Determined by a number of factors, including
genetic qualities, overall health, and potential parenting skills of prospective mates; Animals can detect close relatives
and choose not to breed with them
28. Dispersal: A form of avoiding inbreeding depression; Key mechanism to move gametes away from parent
organism; Includes the movement of the organisms as well
29. Self-incompatibility: A form of avoiding inbreeding depression; The ability of a seed plant to reject its own
pollen and sometimes the pollen of closely related individuals to prevent selfing
30. Dioecy: A form of avoiding inbreeding depression; Organisms are separated into two sexes to avoid selfing
2/8
