Evolutionary Change 5

Question 1

Pleitropy

Answer 1

Multiple phenotypic effects on an individual gene

Question 2

What is antagonistic pleitropy ?

Answer 2

Where the traits controlled by the single gene have opposite effects on an organisms fitness at different stages of life
Eg. Testosterone - increased fitness in early life, then prostrate disorders later on

Question 3

What are the three types of selection ?

Answer 3

1. Negative
2. Positive
3. Balancing

Question 4

What is negative selection ?

Answer 4

Removing all harmful mutations from a population
Line dips below the original phenotype line

Question 5

What is positive selection ?

Answer 5

Increasing the frequency of beneficial mutations that enhance survival or reproduction
Line is to the right of original phenotype line

Question 6

What is balancing selection ?

Answer 6

Maintains genetic diversity by keeping multiple alleles in the population
Line is flat below original phenotype line

Question 7

What is phenotypic plasticity ?

Answer 7

The ability of a single genotype to produce different phenotypes depending on the environment

Question 8

Describe some constraints upon evolutionary change

Answer 8

1. Insufficient genetic variation exists in the gene pool
2. No selection pressure operating
3. Sufficient selection pressure, BUT there exist constraints upon changing the ‘blue print’ of an organism

Question 9

What is a blue print constraint ?

Answer 9

Where the basic structural or developmental “design” of an organism limits how it can evolve
Eg. Arachnid body size, they have to molt their exoskeleton, but if they were large, their bodies would collapse under the weight of their molt

Question 10

What is the red queen hypothesis ?

Answer 10

It means that species must keep evolving just to maintain their current fitness level and survive relative to others in their ecosystem
“It takes all the running you can do, to stay in the same place”