final - post midterm again

Question 1

What is a real world example of directional selection?

Answer 1

Warfarin resistance in mice - resistance evolved rapidly following exposure but declined rapidly after exposure because the resistant allele was not beneficial otherwise - cost of adaptation

Question 2

Insecticide resistance is often based on ___ mutations of ___ ___. Resistance is usually ___

Answer 2

single mutations of large effect
dominant

Question 3

Real example of heterozygote advantage?

Answer 3

sickle cell anemia

Question 4

Define antagonistic selection

Answer 4

A source of selection opposes another source of selection on a trait

Question 5

Two causes of antagonistic selection

Answer 5

Temporal fluctuation - fluctuating environments favour diff genotypes across generations

Spatial fluctuation - different genotypes are best adapted to diff microhabitats

Question 6

Antagonistic and soft selection can lead to ____

Answer 6

multiple niche polymorphism - superior fitness of different genotypes to different portions of an environment - seedcrackers

Question 7

Multiple niche polymorphisms are more likely to occur if each individual only experiences ___ environment

Answer 7

one

Question 8

Define soft and hard selection

Answer 8

Soft - occurs when the survivors of an environment is determined by competition for a limiting factor - the RELATIVELY superior genotype has a higher survival rate

Hard - survival depends on absolute fitness not competitor density

Question 9

What is inverse frequency dependent selection?

Answer 9

the rarer the phenotype , the greater the fitness

Question 10

Why have most organisms evolved a 1:1 sex ratio?

Answer 10

it is an evolutionary stable strategy - selection favors individuals who produce the minority sex - increases the amount of individuals that can actually reproduce- effective population size

Question 11

What is positive frequency dependent selection + examples?

Answer 11

the more common a phenotype the greater the fitness- muellerian mimicry - two species mimicking eachother - increased fitness

Question 12

What is mutation selection balance?

Answer 12

Advantageous alleles should go to fixation but bad alleles can persist in population byu recurrent mutation or gene flow from another population

Question 13

How do selection and drift interact?

Answer 13

drift doesn’t affect a population if selection is strong compared to pop size - but drift and selection can act on the same trait in the same way to move the population to a different adapted peak - a peak shift

Question 14

What is the breeders equation?

Answer 14

R = h^2s where R is response, h2 is heritability and s is selection

Question 15

What is the selection differential?

Answer 15

Difference between mean character in a population before and after seleciton

Question 16

What is correlated selection?

Answer 16

some combinations of traits are favorable - garter snakes - better to be spotted and run away or striped and stand ground but not the other combinations

Question 17

What are the main components of phenotypic variation?

Answer 17

Vg - genetic variance]
Ve - environmental variance

Question 18

Difference between broad and narrow scale heritability - which do we use in the breeders equation?

Answer 18

broad - estimate of variance with a genetic basis - does not reflect amount transmitted between generations

narrow - estimate of variance with an additive genetic basis - does reflect amount transmitted between generations

Question 19

What is one method to estimate heritability? Possible considerations?

Answer 19

parent offspring regression - the slope = h2 if h2 = 0 then there is no variation as there is likely only one possibility
looked at example in beak shape in finches - must be heritable

Question 20

Does a resemblance between parent and offpsirng mean the trait is heritable?

Answer 20

Not always, could be independently determined due to environment

Question 21

Two common issues with parent offspring regressions?

Answer 21

Maternal effects - parents provide more to offspring than genes
Environment - parent and offspring often share environments - environmental factors

Question 22

What is a better way to estimate heritability?

Answer 22

The animal model - needs phenotypic data and pedigree to give heritability

Question 23

What can genetic correlations be due to?

Answer 23

pleiotropy
Linkage diseq

Question 24

If a trait exhibits a genetic correlation with trait 2, then evolution will depend on ______ acting on trait 1 and its _____ with trait 2

Answer 24

the strength of selection and association

Question 25

six causes of linkage diseq?

Answer 25

non random mating
new mutations
union of two populations
low populations
drift
selection

Question 26

What is life history?

Answer 26

age specific probabilities or survival and reproduction

Question 27

Five traits that affect life history?

Answer 27

lifespan
offspring number
offspring size
generation time
breeding events

Question 28

Semelparity vs iteroparity?

Answer 28

semelparity - an organism produces all of its offspring in a single event
iteroparity - reproduces across multiple events

Question 29

Two theories behind why we age?

Answer 29

Mutation accumulation with age
antagonistic pleiotropy

both theories rest on the principle of a selective advantage of early reproduciton

Question 30

Explain how mutations accumulate with age?

Answer 30

Selection will more effectively purge bad mutations affecting early life traits - therefore mutations affecting late life traits can accumulate

Question 31

What are offspring quality / quantity trade offs?

Answer 31

You can generally produce many weak offspring or few strong offspring - negative correlation - need to consider parental survival too

Question 32

Four kinds of sexual reproduction?

Answer 32

outcrossing - mating with another genetically distinct individual
self fertilization - union of gametes produced by the same individual
anisogamy - distinct sexes
isogamy - uniting cells are the same size

Question 33

What is sequential hermaphroditism?

Answer 33

some organisms (fish, worms) change sex over lifespan - predicable using life history

Question 34

Two kinds of asexual reproduction ?

Answer 34

Vegetative propagation - production of offspring from somatic tissue
Parthenogeneis - development from an egg to which there has been no contribution of genes - via apomixis where an individual develops from mitotically produced cells (not meiosis)

Question 35

Pros/ cons of asexual reproduction?

Answer 35

its faster, dont need a partner, more reliable and takes less energy BUT there is ZERO genetic diversity which makes the species unable to adapt to change

Question 36

Why is sexual reproduction preferred despite being seemingly less efficient

Answer 36

asexually producing species seem to have evolved from sexually producing ones
- combines new mutations or rare alleles to create potentially more fit genotypes
- can adapt to varying environments and parasites
- can separate beneficial and harmful mutations

Question 37

What is mullers ratchet?

Answer 37

in an asexually reproducing population more fit genotypes can be lost due to drift - offspring will always carry more mutations than their parents - mutations accumulate - leads to less fitness

Question 38

What is the hill robertson effect?

Answer 38

if a mutates to A and b mutates to B and A and B have higher fitness… without recombination A is in diseq with b and vice versa - beneficial alleles can be lost due to LD with bad alleles

Question 39

Two schools of thought on species?

Answer 39

Nominalism - we make species up
Realism - nature is divided into species

Question 40

Define horizontal and vertical species concepts?

Answer 40

horizontal - aim to define species at one point in time]
vertical - aim to define species across time and which individuals belong to which lineages

Question 41

What is the phenetic species concept?

Answer 41

define species based on shared traits - phenotypes - used to be based only on looks to a wiltype but now has statistics involved

Question 42

What is the biological species concept?

Answer 42

species are groups of potentially interbreeding populations which are reproductively isolated from other groups

Question 43

What is reproductive isolation?

Answer 43

lack of gene exchange between species due to biological not geographic factors

Question 44

What are some prezygotic isolating barriers?

Answer 44

ecological isolation - mates do not meet
temporal isolation - diff breeding times
habitat isolation - diff breeding locations
immigrant inviability - immigrants do not survive long enough to breed

behavioural isolation - prevents mating - assortative mating
pollinator isolation in plants

Question 45

What are postmating isolation barriers?

Answer 45

mating occurs but zygotes are not formed
- mechanical isolation - parts dont fit
- copulatory isolation - failure to fertilize because of behaviour / stimulation
- gametic isolation
-immigrant inviability if mating occurs in a foreign habitat

Question 46

What are postzygotic isolation barriers?

Answer 46

hybrid zygotes are formed but have less fitness
- hybrids do not have a niche
- behavioural sterility - less successful at finding mates
- developmental problems bc hybrid
- sterility for real

Question 47

Primary and secondary hybrid zones?

Answer 47

primary - originate as geographic variation in natural selection alters allele frequencies in a continuously distributed population

secondary - formed when two previously allopatric populations that have become genetically different expand and meet and interbreed

Question 48

Three stages to speciation?

Answer 48

population isolation - divergence - reproductive isolation (following secondary contact)

Question 49

Four modes of speciation?

Answer 49

Allopatric speciation - geographic barrier
Peripatric speciation - founder effects
Parapatric speciation - no physical isolation but wide range
Sympatric speciation - genetic differences - no physical isolation

Question 50

What is a homoplasy?

Answer 50

similar characteristics that have not been derived from a common ancestor