Topic 3 - Fundamentals of Evolution: Natural Selection

Question 1

Observations that lead to natural selection - variation

What is phe variation

Answer 1

There is phenotypic variation

A phenotype is the observable characteristic of the organism. It is the expression of the Genotype

Eg. morphology, behaviour, even products of behaviour (eg nest)

This occurs across organisms

Question 2

Observations that lead to natural selection - hertiability

Answer 2

The phenotypic variation is heritable

Worked out from dog breeders and pigeon fanciers

it can be passed down from parents to offspring

Question 3

Insights of Thomas Malthus

Answer 3

Resources grow linearly

Populations grow exponentially

This will lead to a struggle for existence as individuals compete for resources

Question 4

What is fitness

Answer 4

an individuals ability to survive and replicate

Question 5

Natural selection overview

Answer 5

Phenotypic variation
It is inherited
There is a struggle for existence as individuals compete for resources

some phenotypes will be more successful
Will live longer and reproduce more

Because variation is heritable, there will be more individuals with the successful phenotype in the next generation

Question 6

Selection is acting on phenotypes not genotypes

Answer 6

There can be lots of genetic variation and many different alleles nut there has to be variation in the phenotype to have evolution

If all genotypes have the same color hair, that wont influence fitness of the organisms.

If they all code for different colour hair, this may influence the fitness of the animals (maybe it makes them more or less visible to predators)

Question 7

Alleles

Answer 7

Are the form of a gene

Question 8

Selection is not intentional

Answer 8

It is not choosing the best solution. You might not have designed something this way from the start, evolution works with what is there.

It is a tinkerer, not an architect

Question 9

Adaptations

Answer 9

Are traits that evolved through natural selection

Makes them more or less adapted to their environment and its challenges

Question 10

Lesser/better adapted

Answer 10

Less adapted - you can predict individuals will be less fit

More adapted - the opposite

Question 11

Adaptations are not perfect

Answer 11

They arise from the phenotypic and genetic variation that is present, rather than starting from scratch to build the perfect solution, selection and adaptation work with what is there

Question 12

Adaptation

Answer 12

depends on the physical and social environment the organism finds itself in

Question 13

Generalists/specialists

Answer 13

Adaptation can produce both.

Generalists - more flexible or have more phenotypic plasticity

Specialists - individuals have traits that are more specialized for a particular niche

Neither is better than the other. It depends on the situation and environment.

Question 14

Stabalizing selection

Answer 14

Variation of a characteristic moves closer to the mean

Eg baby size,

too small, cannot thermoregulate. Too big, mum dies

Hence the mean stays the same but the distribution becomes more clustered around it

Question 15

Directional Selection

Answer 15

One specific trait is selected for

eg white mice on white sand. If pop has brown and white fur genes, the white will survive more as it is fitter and camouflaged. Over time, the white phenotype is more common because the brown is less fit

Thus the mean of the group will shift

Question 16

Natural selection

Answer 16

Heritable phenotypes that enhance reproduction and/or survival have increased frequency in later generations.

Results in adaptation
Adapted individuals fit well into their environment
Might be camouflaged or have morphology that helps them to forage or eat