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Biol 214: Genes, Ecology, and Evolution > Final > Flashcards

Final Flashcards

1
Q

population

A

-a freely interbreeding group of individuals living together in time and space

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2
Q

gene pool

A

sum of genetic info present in a population

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3
Q

phenotype

A

a morphological, physiological, biochemical, or behavioral characteristics of an individual organism

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4
Q

genotype

A

the underlying make up of phenotypes

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5
Q

locus

A

a site on a chromosome (or the gene that occupies the site)

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6
Q

gene

A
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7
Q

allele

A

an alternate form/ version of a particular gene/ locus

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8
Q

allele (gene) frequency

A

the relative proportion of a particular allele @ a single locus in a population (b/w 0-1)

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9
Q

genotype frequency

A
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10
Q

mutually exclusive

A

-dependent events
-both cannot occur (1+6 + 1/6)= 1/3
-1 or 2

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11
Q

how many alleles per locus?

A

2

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12
Q

Hardy-Weinberg Law

A

1.) frequency of alleles doesn’t change from generation to generation (frequency doesn’t evolve)
2) offspring genotype frequencies can be predicted from the parent allele frequencies

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13
Q

HW assumption

A

1) no selection
2) no mutation
3) no gene flow or migration
4) no genetic drift (large population)(exchange of genes)
5) random mating

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14
Q

what does any violation of HW mean?

A

evolution

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15
Q

Can HW occur in a gene-by-gene basis?

A

no
total genomic HWE is exceptionally rare

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16
Q

implications of HW principle

A

1) a random mating population w no external forces acting on it will reach the genotype equilibrium
2)any disturbance of the allele frequencies leads to a new equilibrium after random mating
3) amt. of variation is maximized when gene frequencies are intermediate

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17
Q

where can most copies of a rare allele be found?

A

in heterozygotes

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18
Q

4 primary uses of HW principle

A

1) compute genotype frequencies from generation to generation, even w selection
2) serves as a null model in tests for natural selection, nonrandom mating, etc, by comparing observed to expected genotype frequencies
3) forensic and disease analysis
4) expected heterozygosity- provides a useful means of summarizing the molecular genetic diversity in natural populations

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19
Q

2 ways to quantify genetic diversity in population

A

polymorphism- proportion of loci w more than 1 allele in pop

heterozygosity- proportion of heterozygotes in a pop. at a SINGLE locus
OR
proportion of loci heterozygous in an individual genome

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20
Q

what does a true null hypothesis mean?

A

-we are in HWE
-would expect sample of this size to show this much departure (or more) from expectations less than 5% of time

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21
Q

Allozymes

A

enzymes used as molecular markers to assess different alleles (show high heterozygosity)

previously thought that pop wouldnt be variable because 2 allele would grant “best” fitness

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22
Q

what causes genotype frequency differences?

A

the randomness due to punnet squares

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23
Q

migration (gene flow)

A

cause allele frequencies of population to change
- powerful mechanism for small pop. really quickly
-leads to gene flow which tends to homogenize allele frequencies (populations) -> stops process of speciation.

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24
Q

inbreeding

A

-direct violation of hw because violates random mating due to consanguineous relationships
-causes deficit of heterozygote
-selfing is most extreme form of inbreeding

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25
Q

F coeffcient

A

-inbreeding coefficient (quantify heterozygosity)
-quantify amount of homozygosity in pop.
1= completely inbred
0= no inbreeding
as it increases, fitness decreases
-heterozygote advantage decreases (because hetz decrease)

26
Q

inbreeding depression

A

exposure of rare and/pr deleterious alleles increase

27
Q

directional NS

A

-average phenotype moves in 1 direction
-changes average value of trait (increases or decreases)
-variance gets a little smaller
-ex: colored moths

28
Q

stabilizing selection

A

-favor intermediates (more fit)
-heterozygote advantage

29
Q

disruptive (diversifying) selection

A

-heterozygote disadvantage
-intermediates are LESS fit than extremes

30
Q

sexual selection

A

selection that arises from differential reproductive success due to VARIATION in MATING SUCCESS

31
Q

Bateman Gradient

A

-describes a selection gradient for mating success
-the steeper it is, the greater the strength of sexual selection
-variability and reproductive success greater in males because females invest more
-females: reaches an asymptote

32
Q

what did Bateman’s experiment conclude about sexual selection?

A

stronger in males than females because
1) females have limited eggs
2) males have millions of sperm (fitness only limited by how many females can inseminate)
3)in animals, simply due to size and energy differences between eggs and sperm

33
Q

anisogamy

A

a union between 2 gametes that differ in size/ form

34
Q

the fitness of the sex with a steeper Bateman gradient is more limited by the ________ of mates

A

number

-more mates more fitness
-sex dominates to get more mates
-usually males

35
Q

fitness of sex with shallower Bateman gradient is more limited by the ________ of mates

A

quality

-sex wants offspring of the highest quality. leads to “choice” or “choosiness”

36
Q

what does limiting resources for fitness mean?

A

more mates —-> reproduce more

37
Q

sexual dimorphism

A

2 different morphologies

1) morphology (body size)
2) physiology (hormonal differences)
3) behavior (birdsong, dance, humans)

primary sex traits= gonads
secondary sex traits= everything except sex organs
differences between the sexes that do not DIRECTLY participate in reproduction

38
Q

maladaptive traits

A

-traits that conflict with natural selection
-may increase mating success but also decrease survivorship

ex: big antlers energetically costly to an individual. may slow down animal

39
Q

5 extra mechanisms

A

1) scrambles- whoever gets to mate first
2) endurance rivalry- protect mate by being there
3) contests- fighting
4) post-copulatory- sperm competition & infanticide(reproduce w grieving mother)
5) mate choice- offering of nutrition
4&5 happen after sex`

40
Q

when does speciation occur?

A

when gene flow doesn’t

41
Q

how can new species evolve?

A

1) speciation and evolution
allopatric speciation
sympatric speciation

42
Q

micro vs macro evolution in terms of speciation

A

macro-evolution: cladogenesis, speciation
micro-evolution: anagenesis, population new species w same ancestor

43
Q

allopatric speciation

A

-population is divided into geographically isolated subpopulations

-physical isolation creates an effective barrier to gene flow —> divergence

1) physical barrier isolates 1 population
2) isolated pop diverges by NS and/or drift
3) hybridization

44
Q

sympatric speciation

A

speciation occurs in population that live in same area (ranges of population)

-results in formation of 2 or more descendant species from a single ancestral species

-prezygotic isolation

45
Q

hybridization

A

fusion of 2 species to form a new

46
Q

prezygotic barriers

A

-ecological/habitat (never meet)
-temporal- mate at different times
-behavioral- courtship
-mechanical (gametic:gametes cant fuse)

47
Q

postzygotic barrier

A

-egg and sperm unite, zygote forms, results in HYBRID offspring
-mating between individuals of genetically distinct but closely related populations/species

(reduced hybrid viability, reduced hybrid fertility, hybrid breakdown)

48
Q

what happens when diverged populations come back into contact and there is still the potential to interbreed?

A

1) reinforcement to complete reproductive isolation
2) get complete homogenization or fusion -> 2 diverged species fuse into 1 species
3) maintenance of hybrids within a stable hybrid zone
4) hybridization may lead to formation of new species

49
Q

what does hybridization lead to?

A

less fit intermediates

50
Q

what is reinforcement

A

NS that results in a mechanism to prevent hybridization among individuals of diverged populations that are now in secondary contact

51
Q

migration

A

-the movement of alleles among populations
-lead to gene flow
-PREVENTS EVOLUTIONARY DIVERGE OF POPULATIONS

52
Q

genetic drift

A

alteration of gene frequencies due to change (stochastic) effects
-result of finite population size
-causes loss of heterozygosity by random fixation of alleles

53
Q

founder effect

A

change in allele frequency in newly founded population due to colonization of a few founders

54
Q

larger pop size _______ it will take to dix alleles by genetic drift

A

longer

55
Q

Effective population size (Ne)

A

numeber of individuals in an ideal populationwhere rate of genetic drift is the same as it is in actual population
-THE NUMBER OF BREEDING INDIVIDUALS IN THE POPULATION

56
Q

what happens in populations with skewed sex ratios?

A

effective size falls off rapidly

57
Q

what does drift reduce?

A

genetic variation as result of extinction of alleles

58
Q

small populations lose genetic diversity rapidly, which has 2 consequences

A
  1. populations may lose ability to respond to changing environment
  2. loss of alleles entails increase in homozygosity
59
Q

difference between genetic flow and drift

A

flow: genetic migration, mixing of genes
drift: change in existing allele frequency due to random, reduced genetic diversity due to alleles being lost or fixed

60
Q

Mating systems

A
  1. random (HWE)
  2. inbreeding (bw biological relatives)
  3. assortative (preferential b/w phenotypically similar)
  4. disassortive (pref b/w phenotypically different)

Biol 214: Genes, Ecology, and Evolution (5 decks)

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