Midterm 2 Content

Question 1

epistasis

Answer 1

the effect of an allele at one locus depends on the allele at a second locus

Question 2

additive allele

Answer 2

can very predictably see the outcome on the phenotype. twice the phenotypic effect when two copies are present, compared to only when one is present.

Question 3

continuous phenotypes

Answer 3

multiple genes can be involved and impacted by environmental factors

Question 4

heritability

Answer 4

proportion of total phenotypic variance that is attributable to genetic variation among individuals

Question 5

broad sense heritability

Answer 5

measures relative importance of genetic and environmental effects on trait expression

Question 6

narrow sense heritability

Answer 6

proportion of phenotypic variance of a trait attributable to the additive effects of alleles

Question 7

Genome wide association analysis (GWAS)

Answer 7

method for identifying genes associated with a phenotype

Question 8

fitness function

Answer 8

function that relates the phenotypic value for a trait to the average fitness of individuals with that trait value

Question 9

stabilizing selection

Answer 9

narrows width of distribution

Question 10

directional selection

Answer 10

favors one extreme

Question 11

disruptive selection

Answer 11

favors both extremes

Question 12

S= strength of selection

Answer 12

difference between all members in population and mean of individuals that reproduce

Question 13

Breeder’s equation: calculating response to selection

Answer 13

R=h^2S

Question 14

Components of breeder’s equation

Answer 14

R= response to selection
h^2= narrow sense heritability
S= selection differential

Question 15

phenotypic plasticity

Answer 15

ability of individual genotypes to produce different phenotypes when exposed to different environmental conditions

Question 16

reaction norm

Answer 16

range of phenotypes expressed by a genotype along an environmental gradient

Question 17

heritability misconceptions 2

Answer 17

high heritability does not imply determinism

Question 18

heritability misconceptions 3

Answer 18

heritabilities are not constant

Question 19

heritability misconceptions 4

Answer 19

high heritability does not imply genes of large effect

Question 20

heritability misconceptions 5

Answer 20

is a population parameter, so depends on population specific factors

Question 21

speciation

Answer 21

evolution of reproductive isolation within an ancestral species, resulting in two or more descendant species

Question 22

crytpic species

Answer 22

can’t tell difference morphologically

Question 23

Ring species: Ensatinas species

Answer 23

gene flow in hybrid zones and species that are next to each other

Question 24

morphological species concept

Answer 24

group of organisms that look similar to each other and are distinct from other groups of organisms

Question 25

phylogenetic species concept

Answer 25

group of organisms that share a pattern of ancestry and descent and form a single branch on TOL

Question 26

biological species concept

Answer 26

group of organisms that are reproductively isolated from other species. also can interbreed and form fertile offspring

Question 27

allopatry

Answer 27

geographic barriers. species become geographically isolated and no longer able to exchange genetic information

Question 28

types of allopatry: vicariance

Answer 28

geographic barrier divides a population

Question 29

types of allopatry: dispersal

Answer 29

individuals from one population colonize another region

Question 30

sympatry

Answer 30

speciation occurs when populations are in the same geographic area

Question 31

speciation by allopatry example

Answer 31

Cervus canadensis and Cervus elaphus

Question 32

reproductive barriers: before mating

Answer 32

closely related species don't naturally mate due to ecological or phenological barries

Question 33

reproductive barrier: post mating, before fertilization

Answer 33

closely related species can mate, but matings fail to give rise to fertilized eggs

Question 34

reproductive barrier: postzygotic

Answer 34

Bateson-Dobzhansky-Muller incompatibilites - molecular incompatibilites that arise when the genomes of two species are combined in hybrid offspring

Question 35

reinforcement

Answer 35

the evolution of stronger prezygotic isolation because of selection against low fitness hybrids

Question 36

sexual reproduction

Answer 36

reproduction where gametes (haploid cells) combine to form a diploid zygote

Question 37

sex

Answer 37

classification based on differences in gamete size

Question 38

male

Answer 38

smaller, more motile gametes

Question 39

female

Answer 39

larger, more sessile gametes

Question 40

asexual reproduction

Answer 40

cloning

Question 41

isogamy

Answer 41

sexual reproduction by the fusion of similar gametes (mating types)

Question 42

anisogamy

Answer 42

sexual reproduction by the fusion of dissimilar gametes

Question 43

sequential hermaphrodites

Answer 43

start life as 1 sex, over time transitions to other sex

Question 44

simultaneous hermaphrodites

Answer 44

express both sex cells

Question 45

monomorphism

Answer 45

m/f have similar characteristics, so not able to distinguish phenotypically

Question 46

Fisher Muller effect

Answer 46

sex through recombination eliminates competition among beneficial mutations that have arisen in different ethnic backgrounds

Question 47

ruby in the rubbish effect

Answer 47

can't separate deleterious from beneficial mutations

Question 48

red queen hypothesis

Answer 48

species must constantly adapt and evolve to survive against evolving competing species

Question 49

Muller's ratchet

Answer 49

can't remove deleterious mutations once they occur

Question 50

How do asexual species persist?

Answer 50

prokaryotes exchange genetic material with each other through HGT

Question 51

Arrhenotoky: haploi-diploid sex determination

Answer 51

aphids develop into sexually reproducing

Question 52

qualitative vs quantitative

Answer 52

qual: simple, mendelian, small effect on environment, discrete, blood group quant: complex, polygenic, large effect on environment, continuous, weight/ height

Question 53

QTL

Answer 53

chromosome region containing at least 1 gene that contributes to variation in quantitative trait

Question 54

When does sex have stronger selection?

Answer 54

Look for greater variance in reproductive success

Question 55

clonal interference

Answer 55

multiple beneficial mutations arise in individuals but compete with each other rather than combining

Question 56

monomorphism

Answer 56

males and females look identically the same

Question 57

sexual dimorphism

Answer 57

males and females show distinct physical differences