Natural Slection and Fitness

Question 1

Why is it difficult to find evidence for the evolution of behaviour?

Answer 1

Cannot go back in time but comparisons can be made of animals alive today
Helpful when species are closely related so differences are slight and the changes are easier to reconstruct
Can be difficult as behaviours may be found in one population but not in another (cultural transmission, Japanese macaques)

Question 2

Name and describe an example of 2 closely related species in which behaviour can be seen to be different

Answer 2

Colobus monkeys
Red colobus and black and white colobus
both live in E.Africa with overlapping ranges
diet consists of foliage
Red Colobus - lives in wet forests, eats flowers, shoots, fruits and leaves, has 40+ in a troop and has a range of around 1km squared
B&W colobus - lives in dry forests, eats mature leaves of few species, has less than 10 in a troop and has a much smaller range

Question 3

What is the difference between homologous and analogous?

Answer 3

Homologous - derived from a common ancestor (wings of birds, limbs of humans, fins of fish)
Analogous - Solution to a common problem (wings of birds and insects - no common structure)

Question 4

Why have behaviours evolved through time?

Answer 4

Natural selection

• individuals within a species differ from each other (show variation)
• Variation, to some extent, is inherited
• Species individuals produce more offspring that can ever survive

Question 5

How does natural selection favour beneficial behaviours?

Answer 5

Favours foraging behaviours that maximise the amount of energy gained
Favours behaviours that maximise the reproductive success (finding mates with superior qualities)

Question 6

What conditions must change to drive evolutionary change?

Answer 6

Environment must change

Difference must be inheritied

Question 7

What 2 aspects determine wither a trait will be successful or not?
Give an example of this

Answer 7

Costs to the animal
Benefit to the animal
Incubation - benefits - keeps eggs warm, maximises hatching success, increased reproductive success
- costs - no time to forage, immobility of incubating bird

Question 8

Define the term reproductive value and who coined the term

Answer 8

Ronald Fisher 1930
fitness value varies with an individuals age
depends on the ability to reproduce and the ability to survive

Question 9

Name and describe the terms associated with reproductive cycles

Answer 9

Semelparity - single reproductive episode before death

Iterparous - multiple reproductive cycles over a lifetime

Question 10

What is the driving force in life?

Answer 10

Maximising fitness - ensuring the passing on of genetic material from one generation to the next

Question 11

What is inclusive fitness?

Answer 11

Can be maximised at the expense of individual fitness
parents often sacrifice themselves for offspring
important as it explains behaviours impossible to account for

Question 12

What is eusociality?

Answer 12

Different animals have different jobs to do. There is a division of labour. Some castes may be sterile
Animal generations overlap. different generations in the hive or nest
Animals cooperate to care for young

Question 13

What are the 2 ways a behaviour can affect an individuals fitness?

Answer 13

Directly enhacing or inhibiting

Indirectly precluding another behaviour

Question 14

In what ways can fitness be measured?

Answer 14

attempt to specify costs and benefits

measure changes in reproductive output associated

Question 15

What are the 4 aspects that contribute to the variation in fitness of a species?

Answer 15

Ability to survive to reproductive age
success in mating
number of young produced
offspring survival to reproduction

Question 16

Give an example of genetic behaviours and an example of learned behaviour (cultural transmission)

Answer 16

genetic - cricket song (Shaw, 1996) same genus different species different song when bred the hybrid has an intermediate song
leaned - sweet potato washing in Japanese macaques and termite fishing in chimps

Question 17

Give examples of how the benefit of a behaviour outweighs the cost

Answer 17

infanticide in lions

migration in birds

Question 18

Examples of altruism?

Answer 18

killdeer bird
groove-billed ani
meerkats

Question 19

What is altruistic behaviour?

Answer 19

Any behaviour that decreases an individuals fitness but increases the fitness of another individual

Question 20

What is Hamilton’s rule?

Answer 20

rB>C
r = coefficient of relatedness
B= benefit = average number of extra offspring recipient produces
C= How many fewer offspring altruist has as a result
If rB>C natural selection favours altruism

Question 21

What are the temporal and spatial scale?

Answer 21

Temporal: Species can appear fixed at human lifetime scale
Spatial: Species can appear distinct but when compared around the world can be seen to change

Question 22

Describe a study that debates the seemingly altruistic behaviours of meerkats

Answer 22

Tatalovic - 2010
Uses four models of analysing meerkat behaviour to better understand if it is beneficial to the individual or to the group
Found that despite appearing that being a sentinal for the group may be more dangerous that these meerkats were often predated upon least due to the loud noises and position of the meerkats. The behaviour though must have been evolved to fit an altruistic purpose though in that the meerkat puts itself in danger to warn the other members of the group to danger.