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biology year 2 > Population and Evolution > Flashcards

Population and Evolution Flashcards

1
Q

define species?

A

a group of similar organisms that can reproduce to give fertile offspring

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2
Q

define population?

A

a group of organisms of same species living in particular area at particular time - have potential to interbreed

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3
Q

define gene pool?

A

complete range of alleles present in population

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4
Q

define allele frequency?

A

how often allele occurs in population

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5
Q

what does the hardy weinberg principle predict?

A

that frequencies of alleles in population wont change from one generation to the next

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6
Q

what is the hardy weinberg principle only true under?

A

HAS to be

  • large population
  • no immigration
  • no emmigration
  • no mutations
  • no natural selection
  • RANDOM mating
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7
Q

what can the hardy weinberg principle be used to calculate?

A

frequency of particular alleles, genotypes and phenotypes within populations

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8
Q

hardy weinberg equation used to predict allele frequency?

A

p + q = 1

p = frequency of one allele - dominant

q = frequency of one allele - recessive

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9
Q

hardy weinberg equation to predict genotype and phenotype frequency?

A

p^2 + 2pq + q^2 = 1

p^2 = frequency of homo dominant

2pq = frequency of hetero genotype

q^2 = frequency of homo recessive

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10
Q

define variation?

A

differences that exist between individuals

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11
Q

variation within a species means…

A

individuals in pop show wide range of diff phenoypes

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12
Q

what causes genetic variation within a species?

A

when same species have same genes but diff alleles

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13
Q

what is the main source of genetic variation?

A

mutations

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14
Q

how can genetic variation be introduced?

A

during MEIOSIS

  • crossing over chromatids
  • independent segregation
  • random fertilisation of gametes
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15
Q

what variation only results in evolution?

A

genetic

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16
Q

define evolution?

A

frequency of allele in population which changes over time

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17
Q

natural selection is one methof by which…

A

evolution occurs

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18
Q

define selection pressure?

A

anything that affects an organisms chance of survival and reproduction

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19
Q

stabilising selection?

A

individuals with alleles for characteristics towards MIDDLE range more likely to survive and reproduce

20
Q

when does stabilising selection occur?

A

when enviro not changing

  • reduces range of phenotypes
21
Q

stabilising selection e.g.

A

RANGE OF FUR LENGTH

  • in stable climate, having fur at extremes reduces chance of surviving and reproduction
  • harder to maintain right body temp
  • those with average fur length more likely to survive, reproduce & pass on alleles
  • proportion of population with average fur length inc
  • range of fur length dec
22
Q

directional selection?

A

individuals with alleles for single EXTREME phenotype more likely to survive and reproduce

23
Q

when directional selection occur?

A

in response to enviro change

24
Q

example of directional selection?

A

cheetahs - speed

25
Q

disruptive selection?

A

individuals with alleles for extreme phenotypes at either end of range are more likely to survive and reproduce.

26
Q

when does disruptive selection occur?

A

when enviro favours more than one phenotype

(CAUSES EVOLUTION)

27
Q

example of disruptive selection?

A

beak sizes

28
Q

define speciation?

A

development of new species from existing species

29
Q

when does speciation occur?

A

when pop of same species = reproductively isolated

  • change in allele freq changes phenotype
  • no longer interbreed = fertile offspring
30
Q

define geographical isolation?

what does it lead to?

A

when a physical barrier divides a population of species, causing some individuals to = separated from main pop

ALLOPATRIC SPECIATION

31
Q

define sympatric speciation?

A

when population becomes reproductively isolated without any physical separation

32
Q

allopatric speciation

A
  1. geographical Isolation
  2. environmental conditions vary between two habitats
  3. different selection pressures
  4. different alleles advantageous
  5. survive, reproduce to = fertile offpsring - pass on advantageous allele
  6. differences accumulating in gene pools - causes change in phentoype frequencies
  7. = reproductively isolated
33
Q

sympatric speciation

A
  1. new selection pressure occurs
  2. populations remain in the same place
  3. become reproductively isolated
  4. both evolve because of selection pressure
  5. can no longer interbreed successfully
34
Q

what is polyploidy?

A

when mutations occur that inc the number of chromosomes

35
Q

why does reproductive isolation occur?

A
  • changes in alleles and phenotytpes
  • in some individuals prevent them from breeding successfully
  • with individuals without these changes
36
Q

what are the 3 main ways reproductive isolation occurs?

A
  • seasonal
  • mechanical
  • behavioural
37
Q

seasonal

A

individuals with same population develop diff flowering / mating seasons

/

become sexually active at diff times of year

38
Q

mechanical

A

changes in genitalia prevent successful mating

39
Q

behavioural

A

group of individuals that develop courtship rituals that arent attractive to main pop

40
Q

what is evolution by natural selection?

A

when diff selection pressures can change allele frequencies in 2 geographically isolated species

41
Q

define genetic drift?

A

when chance, rather than enviro factors dictate which individuals survive, breed and pass on alleles

42
Q

genetic drift

A
  • variation in genotypes of pop
  • by chance, allel for 1 genotype passed on to offspring more often than once
  • number of individuals with allele in
  • changes in allele frequency in 2 isolated pop leads to reproductive isolation and speciation
43
Q

what does evolution by genetic drift have a greater impact on?

A

pop with

  • smaller pop
  • chance has greater influence

in larger pop

  • chance variations in allele frequency even out across whole pop
44
Q

suggest an explanation for the results in the figure?

A
  • mutation produces KDR minus allele
  • DDT use provides selection pressure
  • KDR minus allele in pop inc
  • those with KDR minus survive, reproduce and pass on allele
  • frequency of KDR minus inc in pop
45
Q
A
  • neurones remain depolarised
  • no AP
46
Q
A
  • sodium ion channel protein changes shape
  • DDTs shape no longer complementary

biology year 2 (29 decks)

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