Greg Hurst

Question 1

Mutation importance

Answer 1

Large effect mutations are commonly lethal so removed by natural selection
Most selection acts on mutations of small effect
Some large mutations can be important eg endosymbiosis

Question 2

Mutations in microbial genomes

Answer 2

Widespread transfer of whole genes between microbes giving functions eg antibiotic resistance

Question 3

Population genetics

Answer 3

Mathematical model of natural selection 
Genetic basis 
Selection coefficients 
Sex and recombination 
Hardy weinburg

Question 4

Egoist - individual selection

Answer 4

Darwin’s opinion
Selection is to maximise individual survival
More reproduction per individual
Traits of individuals make them better competitors and therefore they survive and reproduce by coincidence this may be for the good of the species

Question 5

Altruist - group selection

Answer 5

For the good of the species so species success is maximised eg lemmings commuting suicide when population become too large
However this may be due to coincidence as lemmings disperse more when population is high and have accidents on the way

Question 6

Altruism

Answer 6

Helping relatives - indirectly helping siblings raise offspring you’re also passing on your genes as you share 50% DNA with your sibling or directly by helping your own offspring
Give now receive later - reciprocity eg monkeys grooming each other

Question 7

3 types of mutation

Answer 7

Neutral
Deleterious
Advantageous

Question 8

How do neutral mutations effect genetic diversity

Answer 8

They don’t effect phenotype and are usually in introns or they can affect the phenotype but giving the same properties to the protein
The frequency may increase or decrease randomly as they are not selected for or against
Genetic drift
Will either be fixed or lost
Genetic drift has a bigger effect in small populations

Question 9

How can something get common

Answer 9

Genetic bottleneck

Founder effect

Question 10

Why hasn’t natural selection led to everyone having the same advantageous genes

Answer 10

Evolutionary lag - as soon as one problem is solved the problem changes
The environment changes to quickly for selection to keep up
Convolution produces cycles eg parasites benefit from a host but the host does not so the host selects against so the parasite mutates again and so the host has to also

Balanced polymorphisms -
segregational variation - when the best phenotype involves two alleles together and so is maintained heterozygote advantage
Environmental variation and genetic diversity - lactose requires lactase in humans in some this doesn’t persist to adulthood
Mutations stick in some species but not others

Frequency dependent selection - some traits are good when rare and less when common eg common features of a species are more easily preyed on whereas rare types can survive

Question 11

Sexual selection

Answer 11

Fitness differences associated with acquisition of mates

Question 12

When does sexual selection occur

Answer 12

Variation in phenotype
Some variation is heritable
Phenotype is associated with ability to secure mates

Next gen will be biased towards individuals with higher ability to secure a mate

Question 13

Two forms of sexual selection

Answer 13

Intersexual - female choice

Intrasexual - Male competition

Question 14

Intrasexual

Answer 14

Within the sex 
Large males 
Armaments 
Guard access to females 
Male - Male competition eg stags have large bodies and armaments 
Sexual dimorphism 

Sperm competition - co operative sperm or cloacal pecking

Question 15

Intersexual

Answer 15

Female choice
Quality
Females may choose based on appearance - arbitrary
Direct benefits - food and territory a nuptial gift
Genetic benefits - if the Male has exaggerated traits eg very long tails shows an ‘honest signal’ in some birds

Question 16

Darwin’s postulates

Answer 16

All life is related in a tree

• species split into two called speciation
• intermediate transitional forms between tax’s must have existed in the past
• some clades have gone extinct

Question 17

Divergent / divergent evolution

Answer 17

When one species splits into two new species due to reproductive isolation and different environments etc

Question 18

Punctuated equilibrium

Answer 18

Some species histories are characterised by long periods of stasis followed by sudden changes into new forms called punctuations

Question 19

Hox genes

Answer 19

Transcription factors that alter the expression of other genes
Development of complex form if they mutate they move around morphological segments of insects

Question 20

Is there a tape of life ?

Answer 20

Blind watchmaker view - evolution has no goal or pathway
External events are opportunities for new dominant lines
Not predictable

Programme of life - we are alone in the universe and evolution can be predicted
Eg biotic interactions such as O2 levels at 2400 Mya was 5%
Plate tectonic movement

Question 21

Copes rule

Answer 21

Body mass continues to increase until mass extinction this reduces predation risk

Question 22

Convergent evolution

Answer 22

If there is a common selection pressure in different taxa the same character is derived independently eg birds and mammals have a 4 chamber heart but not related
Same morphologies but derived independently
Analogues not homologues

Question 23

Petrification

Answer 23

Death in water 
Sedimentation 
Burial and pressure 
Bone structures found 
Sometimes carbon containing structures such as leaf prints