L3 Genetic constraints on adaptation

Question 1

Why is a lack of genetic variation a problem?

Answer 1

More variance is a greater tolerance to change

Question 2

Why is higher tolerance to change through variation important?

Answer 2

Means a species can extend their range when conditions change, less tolerance with low genetic variation

Question 3

Why is genetic variation low in the tropics?

Answer 3

Narrow ranges, so likely to be inbreeding, so genetic variation is decreased.

Question 4

How do drosophila illustrate low genetic variation in the tropics?

Answer 4

Very species diverse, across a board range. The species in the tropics show a much lower tolerance to temperature change

Question 5

How could a species overcome the inbreeding depression that comes from having a narrow range?

Answer 5

could move out of their ranges to find other populations and acquire greater genetic diversity

Question 6

How can a species survive in new environments they aren’t adapted to?

Answer 6

Mutations
Phenotypic plasticity
Transposable elements

Question 7

How do mutations facilitate survival in a new environment?

Answer 7

Beneficial mutations can arise and spread through a population

Question 8

What are some examples of adaptation via mutation?

Answer 8

Mosquitos and insecticide, an allele mates which gives resistance to the insecticide, changes the shape of an enzyme so the insecticide isn’t metabolised
Field crickets that are parasitised, parasites find the cricket by song. Mutation arose to produce non signing males, and so were able to avoid the parasite

Question 9

When is is mutation bad?

Answer 9

As mutations accumulate, the mean viability of an individual decreases. Individuals with high mutation rate are less fit. The majority of mutations are harmful. Isn’t available immediately to the whole population

Question 10

What is phenotypic plasticity?

Answer 10

An individual with a genotype that van exhibit multiple phenotype depending on the environment, allowing for flexibility and variance, and may allow persistence in a new environment long enough for selection to take place.

Question 11

How does phenotypic plasticity work in a population?

Answer 11

Only one genotype, so every individual has the ability to adapt to conditions, means that there is nothing for selection to act on

Question 12

How might phenotypic plasticity constrain adaptation?

Answer 12

as exhibited in butterflies, artificial pressures on the species can’t change the reactions it has to the environment, and the genotype is buffered from selection. Will constrain adaptation if the environment fluctuates severely and the individual is unable to adapt

Question 13

What are transposable elements?

Answer 13

Sequences of DNA that jump from one location in the genome to another. May be highly involved in adaptability

Question 14

How may transposable elements be involved in adaptability?

Answer 14

If environment changes, may jump to another location on the genome, the changes occurring may make the individual more adaptable. May preadapt populations

Question 15

Why are invasive species the best to study when looking at adaptability?

Answer 15

A small number of individuals spread into a new environment, and exist in a genetic bottle neck as the gene pool is so small. - chance of success is low, so are good to study as are display efficient adaptability

Question 16

Why do scientists this transposable elements must be important?

Answer 16

Make up a significant part of the genome, so must have a beneficial function

Question 17

What are fitness landscapes?

Answer 17

A useful tool for visualising adaptive peals , a cross section will represent different fitness peaks. A species will one driven up the nearest peak by selection

Question 18

How does drift move species across a fitness landscape?

Answer 18

Doesn’t have much substantial effect

Question 19

Why is adaptability not as simple as a single trait change?

Answer 19

Most traits are related, may be a physiological trade off between investing in one trait over another, some genes may be in linkage disequilibrium, so changes could affect multiple traits

Question 20

What did grant and grants study into Galapagos finches show?

Answer 20

Draught led to larger, harder seeds, so bird bill size adapted to handle the tougher food. However, selection was acting in the opposite direction for bill length - the two traits were correlated so as one increased, so did the other, and it take longer to reach peak fitness.

Question 21

Why are correlated traits important for evolutionary ecology?

Answer 21

Important to figure out how traits influence each other because it is how species will evolve - may allow us to predict how individuals will behave and survive in a changing environment, and can forecast how biodiversity will look in the next decades.