chapter 13 - processes of evolution

Question 1

what is evolution?

Answer 1

genetic/phenotypic change in populations from generation to generation

Question 2

what is Darwin’s theory of selection?

Answer 2

variation among individuals in a population affect their chance of survival and reproduction - natural selection produces evolutionary change

Question 3

what is artificial selection?

Answer 3

selective breeding of plants/animals by humans

ex. dog breeds

Question 4

natural selection vs non-selective (neutral) hypothesis using deer example:

Answer 4

natural selection: deer killed by cars differ in some heritable trait(s) relative to deer not killed by cars
neutral selection: the presence of many deer and many cars result in some deer being killed by cars

Question 5

members of a population must have _____ genetic variation to evolve

Answer 5

heritable

Question 6

genotype vs phenotype

Answer 6

genotype: genetic makeup
phenotype: physical expression of genes

Question 7

when do populations evolve?

Answer 7

when organisms with different genotypes survive and reproduce at different rates

Question 8

do individuals evolve?

Answer 8

no - populations do

Question 9

define a population

Answer 9

a group of the same species that live and breed in a particular geographic area
members become adapted to where they live

Question 10

define adaptation

Answer 10

processes by which useful traits evolve

Question 11

define a gene pool

Answer 11

the sum of all copies of all alleles at all loci in a population
the source of genetic variation

Question 12

define fitness

Answer 12

the reproductive contribution of a phenotype to next generations relative to other phenotypes
essentially: how many viable offspring does the inheritance of this phenotype produce?

Question 13

what are the 3 ways natural selection can act on quantitative variation?

Answer 13

stabilizing, directional, and disruptive selection

Question 14

define stabilizing selection

Answer 14

maintaining the average phenotype

Question 15

define directional selection

Answer 15

selection that favors traits that vary in 1 direction

Question 16

define disruptive selection

Answer 16

selection that favors phenotypes at both extremes away from the mean

Question 17

define sexual selection

Answer 17

acts on characters that determine reproductive success

favors traits that increase chances of reproduction

Question 18

what are the two types of sexual selection? define them:

Answer 18

inTRAsexual: traits like bright colors, long horns, etc. that improve one’s chances of mating compared to other members of the same sex
inTERsexual: traits that are considered more attractive to the opposite sex

Question 19

define allele frequency - what is the equation?

Answer 19

the proportion of an allele in a gene pool
p = (# copies of an allele in a population) / (sum of alleles in the population)
p + q = 1

Question 20

polymorphic vs monomorphic

Answer 20

poly: if a locus as 2 alleles, A and a, that can result in 3 genotypes: AA, Aa, and aa
mono: if a locus only has 1 allele - is a “fixed” allele

Question 21

define hardy-weinberg equilibrium

Answer 21

a model population in which allele and genotype frequencies do not change

Question 22

define genetic structure

Answer 22

the frequency of different alleles at each locus and the frequency of genotypes in a Mendelian population

Question 23

what are the assumptions/conditions required to meet hardy-weinberg equilibrium? (5 conditions)

Answer 23

random mating, infinite population size, no gene flow (migration of genes in and out of the population), no mutation, no natural selection

Question 24

what is the H-W genotype frequency equation?

Answer 24

p^2 + 2pq + q^2 = 1

where p = 1 allele and q = another allele

Question 25

what is the H-W model used for?

Answer 25

measuring deviation from the model & mechanisms of evolution within a population

Question 26

define nonrandom mating

Answer 26

occurs when sexual reproduction is biased in some way

self fertilization is a common form of nonrandom mating

Question 27

mutation as an evolutionary force?

Answer 27

mutation creates new alleles and is the source of genetic variation

Question 28

define genetic drift

Answer 28

random variation in allele frequencies

Question 29

how does population size affect genetic drift?

Answer 29

inversely related
small population = large change by genetic drift
large population = small change by genetic drift

Question 30

what is bottlenecking?

Answer 30

a temporary decrease in population size

much of genetic variation is lost due to bottlenecking

Question 31

what is the founder effect?

Answer 31

the reduced genetic diversity which results when a population is descended from a small number of colonizing ancestors
descendent generations exhibit higher frequencies of alleles present in founder individuals

Question 32

what is a neutral allele?

Answer 32

an allele that doesn’t affect fitness

Question 33

what kind of alleles are subject to natural selection?

Answer 33

alleles that influence individual fitness (survival and reproduction)

Question 34

define positive selection

Answer 34

natural selection increases the frequency of an allele that increases individual fitness

Question 35

define balancing selection

Answer 35

natural selection maintains intermediate frequencies of alleles at the locus because heterozygotes are favored

Question 36

how do rare beneficial dominant vs recessive alleles affect positive selection?

Answer 36

dominant: alleles increase rapidly with positive selection, but change is fast when common
recessive: alleles increase slowly with positive selection, but change is fast when common