POPULATION GENETICS L20

Question 1

evolution

Answer 1

• changes in allele frequency in populations over generations

Question 2

phenotypic variation

Answer 2

• observable differences between individuals
• sometimes either/or – have trait or don’t
• often determined by single gene at single locus

Question 3

genetic variation

Answer 3

• different among individuals in gene or nucleotide sequence

Question 4

sources of genetic variation

Answer 4

• point mutation - new alleles
• changes in chromosome structure
• rapid reproduction
• sexual reproduction

Question 5

population

Answer 5

• group of organisms, potentially sexually inbreeding, of same species living in same area at same time

Question 6

population genetics

Answer 6

• study of genetic variability within populations and the evolutionary forces that act on it
• how genes within populations are changing over generations

Question 7

alleles

Answer 7

• 1 or 2 more alternate versions of a gene

- found on same loci on homologous chromosome

Question 8

gene pool

Answer 8

• all alleles of all genes in a population at any given time

Question 9

fixed allele

Answer 9

• all individuals in a population
• homozygous for same allele
• only 1 allele found at locus for entire population

Question 10

HW equilibrium

Answer 10

• no change in allele frequencies
• explains why dominant alleles are not necessarily more common than recessive
• describes genetics of populations that are not evolving

Question 11

5 conditions required for HW equilibrium

Answer 11

• no mutation
• random mating
• no selection
• very large population (no genetic drift)
• no gene flow

Question 12

somatic alleles

Answer 12

• not passed to offspring

Question 13

morphs

Answer 13

• contrasting phenotypes

Question 14

polymorphic

Answer 14

• populations with 2 or more morphs at detectable frequencies

Question 15

stabilizing selection

Answer 15

• selection for intermediate phenotypes

- common in stable environments

Question 16

directional selection

Answer 16

• selection for 1 phenotypic extreme

- shifts phenotype distribution towards that extreme

Question 17

disruptive selection

Answer 17

• selection for both phenotypic extremes over intermediate state
• occurs when environment is highly variable

Question 18

genetic drift

Answer 18

• random changes in allele frequency
• chance events that alter allele frequencies
• much stronger in small populations

Question 19

bottleneck effect

Answer 19

• size of population drastically reduced
• survival random
• surviving populations have different allergies frequencies from ancestral population

Question 20

founder effect

Answer 20

• small number of individuals colonize a new habitat

- gene pool of new population different from parent population due to small sample size

Question 21

gene flow

Answer 21

• movement of alleles between populations
• effect of migration
• most natural populations have some level of movement by individuals
• reduces differences between population
• changes allele frequencies in both