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Evolution > MIDTERM 2 > Flashcards

MIDTERM 2 Flashcards

1
Q

genetic locus

A

location of a gene or sequence within a chromosome

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2
Q

alleles

A

forms of a specific gene within a locus

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3
Q

What does the hardy-weinbergn principle states?

A

alleles frequences remain the same from gen to gen

phenotypic frequencies remain the same gen to gen

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4
Q

What circumstances are not considered in the hardy weinbergn princle?

A

large populations

different genotypes that differ in fitness

mutations

random mating

migration is not involved

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5
Q

what are the reasons why the genotypic frequencies do not conform to the weinberg principle?

A

nonrandom mating

or. evolution

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6
Q

what are mechanisms that populations evolve?

A

This cause the change of allelic frequencies.

gene drift

natural selection

migration (gene flow)

mutation

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7
Q

what is pleiotropy

A

a mutation in a gene can cause affect of many phenotypic traits

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8
Q

what is additive?

A

its an allele that yields twice the phenotypic effect when two copies are present

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9
Q

what is a polygenic trait?

A

a trait that influences other loci (influences other parts of a gene)

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10
Q

what is an example of the effects of a polygenic trait

A

interactions between alleles (epistatsis)

environment interactions (phenotypic plasticity)

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11
Q

Quantitative genetics

A

continuous phenotypic traits ex complex traits

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12
Q

how do you know how much a population changes

A

depends on selection differential and heritability

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13
Q

what is a quantitative trait locus?

A

it analysis links traits with genes

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14
Q

Phenotypic Plasticity

A

a single genotype that produces more than one phenotype depending on the environment

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15
Q

Reaction Norm

A

can predict the response in environment using maps.

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16
Q

what is an example of genetic synapomorphy?

A

the change of nucleotide base.
ex, G to T

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17
Q

what is positive selection?

A

allele that is involved in selective pressure evolve quickly therefore shorter distance to coalescence

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18
Q

Introgression

A

is where two species that are closely related to each other and still reproductivly compatabilite can interbred and produce a hybrid

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18
Q

what are synonymous mutations?

A

they are silent mutations that do not alter the amino acid seq of protein.
they are within the coding regions (exons)

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19
Q

why do genes differ in rate of evolution?

A

mutations on exons form slowly evolving genes useful for distantly related species.

mutations on introns form rapid evolving genes useful for closely related lineages

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19
Q

promiscuous

A

proteins capable of carrying out more than one function

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20
Q

what are non-synonymous mutations?

A

alter the amino acid seq of protein. Can affect splicng and regulation of gene expression

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21
Q

what is broad sense heritability?

A

Phenotypic differences are explained by genetic differences among individuals

22
Q

What is narrow sense heritability?

A

phenotypic variences are explained by ADDITIVE genetic variation (cause offspring to look like parents)

23
Q

How do you estimate heritability?

A

The slope indicate narrow sense heritability (additive trait)

24
Q

what does broad sense heritability include?

A

additive effects

dominance effects

Epistatic effects

Maternal/Paternal environment effects

25
Q

What makes a stabilizing selection?

A

when the oppsite sites oppose each other

26
Q

how much the population changes?

A

by selection differential and heritability

27
Q

What happens to the selection differential if the strength of selection is strong?

A

the selection differential (S) will be large and only the biggest individuals reproduce

28
Q

what happens if the selection differential strength is weak?

A

The selection differential (S) is small and only big and medium individuals reproduce

29
Q

how much will a trait evolve using the narrow sense and selection differential (S)?

A

R= h2xS

30
Q

what are the forms that selection on quantitative traits occur

A

directional

stabilizing

disruptive

31
Q

Can selection occur without evolution?

A

yes it can occur without evolution. Selection can occur by the strength of selection and heritability

32
Q

how is the distance of coalescence from a time where strong positive selection occur?

A

The distance back to coalescence will be short because the selection is increased to fixation

33
Q

what is homoplasy in phylogenetic trees?

A

there is a same mutation that occurs at the same base in seperate lineages

34
Q

how does gene differ in rate of evolution?

A

slowly evolving genes are distantly related. (occur on exons, more convervative regions

Rapidly evolving genes are closely related (occurs on non-coding regions, less conservative

35
Q

what are the important points of Darwins study?

A
  • single colonization event and then diverification occurs forming monophyletic groups
36
Q

what is a molecular clock?

A

able to date fossils or events that can tell how long two lineages diverged

37
Q

what is the molecular clock used for?

A

used to estimate the origin of disease and major clades

38
Q

what happens to alleles when subjected to strong selection?

A

they spread quickly through populations

39
Q

what is selective sweep?

A

adaptive allele spreads through population quickly lead to reduced genetic diversity

40
Q

what is genetic hitchhiking?

A

strong selected alleles are found in a population surrounded by the same set of alleles at neighboring locations

41
Q

what selection will leave genetic signatures that can be detected?

A

positive and purifying selection

42
Q

what is the difference between the bacterial genome and eukaryotic genome?

A

Bacterial:
- size dependent on many genes
- Duplication, lateral gene transfer and increase size
- bacteria adapted to host have smaller genome and lose functional genes

Eukaryotic:
- have more noncoding DNA than number of genes
- mobile elements contribute to a large portion of the genome size

43
Q

what are complex adaptations?

A

they are co-expressed traits that experience selection for a common function

44
Q

what are casades?

A

They are regulatory networks that includes multiple genes that are dependent on each other

45
Q

whats happens when a chromosome is duplicated?

A

can make function of a gene work differently

46
Q

what happens to citrate metabolism?

A

a gene duplication insertion occurs causing the rnk promoter to express citT when oxygen present leading to the functioning of the transporter

47
Q

what is the history of venom?

A

Initial Duplication:
Beta-defensins are produced in skin to fight bacterial

Second duplication:
Beta-defensins are expressed in snake pancreas and other organs due to mutation in regulatory element

Third duplication:
evolve into crotamine venom and expressed only in venom glands in snakes

48
Q

what is the evolution of eyes

A

First duplication event:
a G-protein receptor was duplicated and evolved one copy with a hormone called melatonin and the other opsin

Second duplication event:
Opsins evolve to capture photons in animals. After duplications, opsins evolve to t-opsins in cnidarians, protosomes, and deuterostomes

Third duplication event:
produce two other types of opsins: c-opsins and RGR/Go opsins

49
Q

how did crystallins evolve?

A

through gene recuitment.
a mutation causes a whole different function

50
Q

what is constraining evolution?

A

laws of physics

pleiotropy

51
Q

what is antagonistic pleiotropy?

A

negative side affect of genes
ex. giraffe with one cervical vertebrae can cause depressed metabolism and increase cancer rates

52
Q

what is parallel evolution?

A

Independent evolution of similar traits from similar ancestral

53
Q
A

Evolution (3 decks)

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