Midterm 1 Flashcards by Andres Nunez

What is evolution?

Change in allele frequencies over generations

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What are the four forces of evolution?

Natural selection, new mutants, migration, and genetic drift

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What is natural selection?

Individuals surviving or reproducing better than others because of their alleles and resulting phenotypes

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How do we know there was no migration that caused tusklessness in the female elephants?

There were no recorded migrations i think??? Idk

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Why can we rule out new mutations being the result of the increase in tusklessness?

After one elephant generation, the increase that was observed is literally impossible to have happened because of tusklessness being recessive

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What did the computer simulation for the elephants do and what did it determine?

Simulated the pre-Civil war populations and tested almost every reproduction possibility, found that the tusklessness at BEST hits 25% which did not match irl

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How did they find the genes responsible for tusklessness?

Sequenced the genome of tuskless elephants and compared it to tucked elephants and looked to see where the major differences are

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What was the name of the gene was controls tuskelssness in elephants?

AMELX

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What is fitness?

How good a genotype is in an environment

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How do you calculate the selection coefficient, s?

1-fitness

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Are all mutations equally likely?

No, some genes have a higher mutation rate than others

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Why don’t super viruses evolve?

you can’t be super virulent and transmissible because killing your host before you spread is not optimal

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Does the ability to infect different types of hosts increase or decrease fitness?

INCREASE

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Why do bats and rats have so many damn viruses?

They’re super diverse species that allowed the viruses to slowly adapt to that diversity

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What is epistasis?

Swapping mutations

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What is pleiotropy?

One allele/mutation that affects SEVERAL things simultaneously

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What are vestigial structures?

Structures that an animals ancestors once used but no longer have a use now so they’ve become irrelevant like whale legs

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What theory does fossil geography matching up with currently similar species support?

Evolution duh

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Do you remember the snail example? Describe it

Snails have striped shells, those with the most obvious shells were eaten by birds

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What is the fitness equation?

W bar = lxmx
w bar is fitness
Lx is survivorship
Mx is mating

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Is fitness a parameter or statistic?

Parameter

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What is a midparent measurement?

The measurement in question (ex. Beak length) is averaged between to the two parents

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Do you remember the finch drought example? Describe it

Drought fucked up a ton of finches and only left 90 survivors, an extreme bottle neck event

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What would a midoffspring midparent graph with a slop of 0 represent?

The trait in question is caused by the environment, no correlation to genetics

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What would a midoffspring midparent graph with a slope of 1 represent?

ALL due to genetics

Why wasn’t there a big change in mean phenotype?

1. The survivors were mostly of that size anyways 2. Their beaks could eat the seeds available

How can you calculate the mutation rate?

Count how many changes there are in phenotype

Are mutations usually deleterious or beneficial? You know it im just making a card

Deleterious obviously

Do different organisms have different mutation rates?

Yup

What happened when you let mutations accumulate without the effects of survival of the fittest?

They fucking DROP but it recovers once survival of the fittest is allowed again

What was the classical school of thought on variation?

Variation is low and harmful

What is the balance schools belief on variation?

variation is beneficial and there should be TONS

What is the HW equilibrium and what model is it used as?

P^2+2pq+q^2=1, null model

What is the Wahlund effect?

Reduction in observed heterozygosity compared to expected due to population structure, caused by selective pressure

What’s the equation of reduced heterozygosity? What is it quantified as?

FI = (HE-HO)/HE, E being expected and O being observed, quantified by the inbreeding constant

What happens to alleles after a while?

Allele fixation

What’s a good example of species bottlenecking?

Cheetah’s, their effective population is very small

The smaller the population, the ___ heterogeneity

What is effective population size?

Ne, the number of individuals in a theoretical population having the same magnitude of genetic drift as the actual population

What’s the equation of effective population size?

He = (4NmNf)/(Nm+Nf) or 1/Ne = 1/t SIGMA 1/Nt

As populations increase, polymorphism ____

Increases

What is the equation of mutation effects on alleles?

Peq=v/u+v, qeq = u/u+v A->a rate = u, a->A rate = v

What is the equation of allele changes considering migration?

P’ = (1-m)p+mp* P’ - p frequency in migration origin P - p frequency in migration destination Q’ - q frequency in migration origin Q - q frequency in migration destination M - migration rate

What are the equations of fitness for all 3 genotypes? (AA, Aa, aa)

MAALAA MAaLAa MaaLaa

What is the equation of average fitness?

W bar = wAAp^2 + wAa2pq + waaq^2

What does particulate inheritance go against?

Blending inheritance

With more loci affecting a gene, there are ____ intermediates

What’s the breeder’s equation?

R = h^2 S H^2 = heritable variation (narrow sense) S = Selection R = response to selection

What is the possible range of h^2?

0 to 1

What is the equation of h^2 BROAD sense?

VG/VP or VG/VG+VE

What are the 3 components of VG?

VA, VD, VI, additive dominant Epistatic effects on alleles, VA IS MOST IMPORTANT

What is the equation of h^2 NARROW SENSE

VA/VP

Are broad sense and narrow sense equal?

Yup

What is the h^2 really measuring?

genetic variation / phenotypic variation

What is the slope of a midparent offspring regression?

H^2Normal, if the slope is 0 that means theres no heritability

What are the two components of VP?

VG + VEnvironment

What do gene environment correlations do to h2?

Inflate estimates of h2 in wild populations

What is a selection differential?

Difference between means of t bar and t*, t* is after selection is applied

What is a selection gradient?

Slope comparing relative fitness and a trait

What do additive gene graphs look like?

A positive slope, +0.5 per A allele

What do dominant gene graphs look like?

0 at aa, +1 at Aa and AA

In sexually reproducing species, parents transmit ___ not ___

Alleles not genotypes

What is VG?

The average affect of an allele on offspring phenotype

What would the differential and gradient graph look like if selection was stronger?

Farther for differential, steeper for gradient

What would the differential and gradient graphs look like with weaker selection?

Closer for differential, less steep for gradient

Why is relative fitness measured?

It scales fitness based on average survival

What is another word for R, response to selection?

Evolution

What is a QTL?

Quantitative trait loci

What’s a manhattan plot used for?

Finding QTLs

How can you tell if a graph describes selection versus heritability?

Heritability compares parents and children, selection discusses fitness

How can you tell if a QTL affects a trait?

Different alleles of that QTL affect that trait and cause a change

More markers leads to ___ resolution

Higher

What does LOD mean?

log of the odds

Can QTLs that affect different traits be coinherited?

Absolutely

What is directional selection?

Large or small trait values

What is stabilizing selection?

Intermediate trait values

What is disruptive selection?

Extreme trait values

What is the only thing that causes adaptation?

Selection

How do you demonstrate a trait is an adaptation?

Experiment with the isolated trait

What makes a good test for the adaptive hypotheses?

Good controls, randomization, sufficiently large sample sizes

What is the comparative method?

Comparing traits between different groups (ex. Bigger bat groups have bigger balls cus of sperm competition) requires a phylogenetic tree as well

What are things that constrain evolution?

Trade offs of resources

Do you need to know the underlying genes to demonstrate that a trait is an adaptation?

NOPE

What’s the equation for s, the selection coefficient?

1-w=s

Are marker loci used to find the QTL or is the QTL used to find the marker loci?

Marker to find QTL