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biology - genetics > evolution lectures 3/4 > Flashcards

evolution lectures 3/4 Flashcards

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1
Q

What is the defintion of a population?

A
  • localised group of interbreeding and interacting individuals
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2
Q

how many populations make up a species?

A

one to many populations make up a species that can interbreed when they meet

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3
Q

Genetic varibility

A

in most species, individuals are heterozygous at many loci/ places
- typically 2-10% heterozygousy

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4
Q

source of genetic variability

A

new alleles arse by mutations to existing alleles

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5
Q

most mutations that don’t meaningfully affect fitness are called what?

A

neutral alleles

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6
Q

alleles that when mutated harm fitness?

A

harmful alleles

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7
Q

alleles that mutate to help fitness?

A

beneficial alleles

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8
Q

what is gene flow?

A

when alleles from one population are introduced to another population

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9
Q

what is a gene pool?

A

all alleles at all gene loci in all individuals

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10
Q

what are “fixed” alleles?

A

where the whole population is homozygous at locus (plural of loci)

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11
Q

what are polymorphic loci?

A

2 or more alleles in a population,

have the some frequency

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12
Q

microevolution

A

the change in the frequencies of different allele in the gene pool over generations

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13
Q

how to calc allele frequencies

A

allele of interest/ total allele count

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14
Q

what does the Hardy- Weinburg principle describe

A

expected relationships between alleles and genotype frequencies with NO EVOLUTION
- assumes random mating

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15
Q

what are the assumptions of the Hardy Weingburg Principle

A

1) no net mutations
2) random mating
3) no natural selection
4) large (infinite) population size
5) no migration

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16
Q

what do violations of the Hardy-weing burg principle assumptions indicate?

A

evolutionary change

17
Q

what are the three causes of microevolution?

A

natural selection
gene flow
genetic drift

18
Q 
which of :
- natural selection
- gene flow
genetic drift 
result in adaptive evolution/ adaptation?
A

natural selection is the only one that results in adaptations

19
Q

what is gene flow?

A

dispersal of gametes or migration

gene flow can introduce new alleles to a population

20
Q

random genetic drift can lead too_______

A

fixation or extinction of alleles in absence of natural selection

21
Q

what is the rate of drift related to?

A

population size

- rate of drift faster in small populations than large

22
Q

a natural allele at 0.5 is equally likely to____

A

be fixed or go extinct

23
Q

what are genetic bottlenecks?

A
  • breeding population is very small for a period of time

- because of this, genetic drift is very powerful

24
Q

what happens to the diversity of the population during genetic bottlenecks?

A

diversity goes down

- sometimes rare alleles up in frequency because diversity is generally donw

25
Q

how do captive breeding programs manage diversity?

A

by introducing others from different populations

26
Q

what is the founder effect?

A

a special case of genetic bottleneck

  • few individuals of population go form their own
  • when their new population is gornw, some rare alleles from the old population are more frequent in the new one
27
Q

what is polygenic inheritance?

A

phenotype influence by several different genes

28
Q

stabilizing selection

A

the outer most phenotypes are selected against

29
Q

disrupting selection

A

middle/ intermediate phenotypes selected against

30
Q

sexual selection

A
  • competition for mating opprotunites

- results in adaptations that increase mating success

31
Q

is there any down fall to sexual selection?

A

sometimes the adaptations that increase mating sucess can reduce rate of survival

32
Q

intrasexual selection

A

competition within one sex for mating opprotunities

- usually within males

33
Q

intersexual selection

A

one sex choose mate from competing memebers of opposite sex

- usually female choose males

34
Q

preserving allelic variation

A

diploidy hides recessive alleles when they are rare

- dont see the recessive allele even thoght its there, because individual is heterozygous

35
Q

heterozygous advantage: sickle cell amneia

A

recessive
- ss die young
- SS resistance to malaria
malaria absent: SS and Ss similar fitness
malaria present: Ss higher fitness than SS

36
Q

inverse frequency-dependant selection

A

rarity increases relative fitness of a variant

biology - genetics (8 decks)

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