Exam 2

Question 1

allele frequencies

Answer 1

rates of occurrence of alleles in a population

= number of specific allele/ total # of alleles in population

Question 2

fixed allele

Answer 2

when a population exhibits only one allele

Question 3

fitness

Answer 3

number of offspring that are able to reproduce

Question 4

modern synthesis

Answer 4

ronald fisher’s formed a synthesis between mendelian genetics and darwin’s theory of natural selection

Question 5

positive selection

Answer 5

natural selection that increases the frequency of an allele

Question 6

negative selection

Answer 6

natural selection that decreases the frequency of an allele

Question 7

balancing selection

Answer 7

maintenance of multiple alleles; acts to maintain two or more alleles in a population
ex: heterozygote advantage over homozygotes

Question 8

stabilizing selection

Answer 8

maintains the status quo and acts against extremes ex: birth weight

Question 9

directional selection

Answer 9

leads to a change in the trait over time

ex: artificial selection: competitive element is removed.

Question 10

disruptive selection

Answer 10

operates in favor of extremes and against intermediates

Question 11

migration

Answer 11

the movement of individuals from on population to another resulting in gene flow

Question 12

gene flow

Answer 12

movement of alleles from one population to another

Question 13

genetic drift

Answer 13

random changes in allele frequencies from generation to generation; significant in small populations

Question 14

bottleneck

Answer 14

when an originally large population falls to just a few individuals

Question 15

founder event

Answer 15

a few individuals start a new population

Question 16

SNP

Answer 16

single nucleotide polymorphism; each nucleotide pair is common enough in the population to be present in a random sample of 50 diploid individuals;
eye color associated with this

Question 17

sexual selection

Answer 17

promotes traits that increase an individual’s access to reproductive opportunities

Question 18

intrasexual selection

Answer 18

focuses on interactions between individuals of one sex

Question 19

intersexual selection

Answer 19

focuses on interactions between females and males

Question 20

species

Answer 20

individuals that can exchange genetic material through interbreeding; share alleles with each other

Question 21

gene pool

Answer 21

all alleles present in all individuals in the species

Question 22

Hardy Weinberg Conditions

Answer 22

1. no difference in reproductive success 2. no fluctuation in population 3. no mutations 4. population must be large 5. Individuals must mate at random

Question 23

inbreeding depression

Answer 23

a reduction in the childs fitness caused by the homozygosity of deleterious recessive mutations

Question 24

autosome

Answer 24

non sex chromosome

Question 25

epistasis

Answer 25

multiple genes act in the same pathway to affect a trait

Question 26

linkage mapping

Answer 26

frequency of recombination used as a measure of the physical distance between genes

Question 27

timescale of evolution

Answer 27

1. generation time of organism 2. strength of selection 3. starting frequency of selected allele- T, S,SF

Question 28

reciprocal crosses

Answer 28

male and female are switched genotypes to determine whether the gene is sex linked.
should be no difference in F! generations if not sex linked

Question 29

recombinant frequency

Answer 29

= (# recombinants)/(total # of offspring) x 100

50 or more map units apart= act like on different chromsome

Question 30

greater chance of physical distance

Answer 30

greater chance of crossover

Question 31

relative fitness

Answer 31

= (# of offspring with genotype 1)/(# of offspring of genotype 2)
genotype 2 must be the highest fitness in the population

Question 32

anisogamy

Answer 32

gametes of different sizes
males- make many, small gametes
females- make fewer, larger gametes

Question 33

sexual dimporphism

Answer 33

differences between the sexes in traits often related to attracting and obtaining mates