2.2b Fitness and Co-evolution

Question 1

What is fitness an indication of?

Answer 1

an individual’s ability to be successful at surviving and reproducing

Question 2

What is fitness a measure of?

Answer 2

the tendency of some organisms to produce more surviving offspring than competing members of the same species.

Question 3

What does fitness refer to?

Answer 3

the contribution made to the gene pool of the next generation by individual genotypes

Question 4

What are the two different terms for fitness?

Answer 4

• absolute
• relative

Question 5

What is absolute fitness

Answer 5

the ratio between the frequency of individuals of a particular genotype after selection, to those before selection

Question 6

What is the equation for absolute fitness?

Answer 6

frequency of a particular genotype after selection / frequency of a particular genotype before selection

Question 7

What do the values of absolute fitness indicate?

Answer 7

• If the absolute fitness is 1, then the frequency
  of that genotype is stable.
• A value greater
  than 1 conveys an increase in the genotype
• a value less than 1 conveys a decrease.

Question 8

What is relative fitness?

Answer 8

the ratio of the number of surviving offspring per individual of a
particular genotype to the number of
surviving offspring per individual of the most
successful genotype

Question 9

What is the equation for relative fitness?

Answer 9

number of surviving offspring per individual of a particular genotype / number of surviving offspring per individual of the most successful genotype

Question 10

What is co-evolution?

Answer 10

the process by which two or more species evolve in response to selection pressures imposed by each other

Question 11

What acts as a selection pressure in co-evolution?

Answer 11

a change in traits of one species acts as a selection pressure on the other species

Question 12

When is co-evolution frequently seen?

Answer 12

in pairs of species that have symbiotic interactions

Question 13

What is symbiosis?

Answer 13

co-evolved intimate relationship between members of two different species

Question 14

What can the impacts of co-evolution be for the individuals involved?

Answer 14

• mutualism (+/+)
• commensalism (+/0)
• parasitism (+/-)

Question 15

What is mutualism?

Answer 15

both organisms in the interaction are interdependent on each other for resources or other services. As both
organisms gain from the relationship, the interaction is (+/+).

Question 16

What is commensalism?

Answer 16

only one of the organisms benefits (+/0)

Question 17

What is parasitism?

Answer 17

the parasite benefits in terms of energy or nutrients and the host is harmed as the result of the loss of these resources (+/-)

Question 18

What is the Red Queen hypothesis?

Answer 18

in a co-evolutionary relationship, change in the traits of one species can act as a selection
pressure on the other species

This means that species in these relationships must adapt to avoid extinction