Populations and Evolution Word Stimulants

Question 1

Allele frequency

Answer 1

Number of times an allele occurs in a gene pool

Question 2

Gene pool

Answer 2

Total of all the alleles of all the genes of a population

Question 3

Hardy Weinburg principle purpose

Answer 3

Allele and genotype frequencies in a gene pool of a population remain constant
Generation to generation

Question 4

Hardy Weinburg conditions

Answer 4

Not disturbed by different influences

Only possible in a lab (provides standard)

Question 5

Disturbing influences

Answer 5

Mutation
Genetic drift
Small population size
Gene flare
Non random mating
Selection

Question 6

p + q = 1.0 (100%)

Answer 6

Used to calculate allele frequency
p - frequency of dominant
q - frequency of recessive

Question 7

p^2 + 2pq + q^2 = 1.0 (100%)

Answer 7

AA + 2Aa + aa = 1.0

3 possible genotypes

Question 8

Variation

Answer 8

Differences in characteristics between individuals

Same/different species

Question 9

Continuous Variation

Answer 9

Variations spread over a range of measurements
All intermediates possible between 2 extremes
Eg Height
Distribution curve

Question 10

Discontinuous variation

Answer 10

Distinct categories
Eg blood group
Bar Chart

Question 11

Environmental causes of variation

Answer 11

Nutrients (food, minerals)
Drugs (serious effect on appearance)
Temperature (effects rate of enzyme-controlled reactions)
Physical training (more muscle used, increase in size/power)

Question 12

Genetic causes of variation

Answer 12

Mutations

Meiosis events

Question 13

Meiosis events - variation

Answer 13

Homologous chromosomes (pair, independent assortment - segregate independently > daughter cells)
Sex cells (gametes) vary genetically - chromosome pairings
New parent allele combination in zygote (random mating/fertilisation) - genetically different offspring
Crossing over - recombination of chromosomes

Question 14

Carrying capacity

Answer 14

Resources available enable population to survive in its niche

Question 15

Fundamental niche

Answer 15

Resources available to a species in the absence of competition

Question 16

Realised niche

Answer 16

Resources available to a species in the outcome of competition

Question 17

Natural selection

Answer 17

Mechanism of evolution

Question 18

Natural Selection steps

Answer 18

Individuals vary genetically (characteristics slightly different)
Limited resources
Advantageous alleles/characteristics favoured for - better compete for resources, better adapt, more likely to survive & reproduce (offspring inherit)
Favourable alleles/characteristics accumulate in population
Descendent allele frequency different to ancesteral
Specialisation

Question 19

Competition

Answer 19

Stop over production
Species equilibrium - carrying capacity of niche
Niche sets upper capacity
Realised niche
More intense = greater selection pressure = increases rate of divergence

Question 20

Divergence

Answer 20

Races > subspecies > species

Question 21

Speciation

Answer 21

Formation of new species
Result of natural selection
Outcome of evolution

Question 22

Measuring rate of evolution

Answer 22

Measure change of allele frequency in one population

Question 23

Selection pressure

Answer 23

Change in environment

Stimulates evolution

Question 24

Evolution

Answer 24

Change over time

Change in allele frequency

Question 25

Stabilising selection

Answer 25

Stable environment Low selection pressure Extremes selected against Close to average selected for - more likely to reproduce (pass on alleles) Species change very little - maintains consistency; descendent look like ancestors

Question 26

Directional selection

Answer 26

``` Rapidly changing environment High selection pressure Selection pressure favours individuals with adaptation (pass on alleles) Long term trend = new species New species arise quickly Descendent do not look like ancestors ```

Question 27

Disruptive selection

Answer 27

Variety of selection pressures in an environment Both extremes selected for - co existing of species (polymorphic) Average selected against Two new species form

Question 28

Isolating mechanisms

Answer 28

Divergence of gene pools

Question 29

Deme

Answer 29

Separated components of a single population Encounter and respond to slightly different circumstances of fragmented environment (adapt through natural selection over time > speciation)

Question 30

Allopatric Speciation

Answer 30

Geographical separation (demes isolated) Meeting and mating interrupted (free flow of genes restricted) Demes respond to their environment (selection pressures) Deme allele frequencies change (different to pool genes of other demes) Divergence from original population New species

Question 31

Sympatric speciation

Answer 31

``` Same environment Isolated Cannot interbreed/ not exchanging alleles Free flow of population interrupted Divergence > new species ```