Natural selection and sociobiology

Question 1

Give the definition of adaptation

Answer 1

Short term change within a species

Question 2

Give the definition of evolution

Answer 2

Long term change that results in the appearance of a new species. This is macro evolution.

Question 3

Give an example of microevolution

Answer 3

Behavioural adaptations is an example of microevolution. Changes in a species that is visible which helps them to adapt to their environment but doesn’t lead to a whole new species.

Question 4

How do species change over time?

Answer 4

By a process called natural selection. This is the primary mechanism of biological change over time. involves adaptation and evolution.

Question 5

What are the 3 fundamental observable facts natural selection is based on?

Answer 5

• Variation
• Inheritance
• Overproduction

Question 6

How does variation come about within and between species?

Answer 6

• Random mutations

- Random genetic recombination due to mating and non random mate choices.

Question 7

What is inheritance and who discovered the principles of it?

Answer 7

Variation passed from parent to offspring discovered by Gregal Mendall

Question 8

What is overproduction?

Answer 8

There are always more offspring born than can or do survive adulthood.

Overproduction means competition to survive adulthood - some will survive to adulthood, others will not.

Question 9

In terms of the principles of overproduction, what individuals are most likely to survive until adulthood and who won’t?

Answer 9

Those that will survive will happen to have variation in their morphology and behaviour that helps them to survive.

Those that don’t will have maladaptive morphology or behaviour which doesn’t enable them to survive.

The environment naturally selects some variants over others.

Question 10

Give an example of a species that would be less likely to survive due to a maladaptive morphology exacerbated by climate change.

Answer 10

When a hare doesnt change its coat in time for summer it becomes a maladaptive morphology.

Climate change is causing the snow to melt so animals aren’t changing their coats fast enough so there is higher predation which leads to population decline.

Question 11

What two elements are key in understanding adaptation, and evolutionary change over time?

Answer 11

Survival and reproduction

Question 12

What is meant by ‘fitness’?

Answer 12

The ability to live and reproduce.

High fitness = high reproductive success.

Low fitness = low reproductive success.

Question 13

Describe what is meant by natural selection

Answer 13

Those traits possessed by individuals that survive longer and have high reproductive success, will be passed to future generations at higher rates.

The environment naturally selects some variations (some individuals) over others to survive and reproduce.

The population, over time, becomes better and better adapted to their local environment.

Question 14

How does natural selection link to adaptation/evolution?

Answer 14

The differential survival and reproductive success in each parental generation (natural selection) LEADS TO a change in the frequency of traits from one generation to the next (adaptation/evolution)

Question 15

What traits will appear in increased frequency in future generations?

Answer 15

Traits that are well suited to the environment that give individuals an advantage in survival and reproductive success.

Question 16

What traits will appear in decreased frequency in future generations?

Answer 16

Traits that are not well suited to the environment that puts an individual at a disadvantage in survival and reproductive success.

Question 17

Give an example of natural selection producing adaptation

Answer 17

high proportion of rattlesnakes in the southern us that dont rattle anymore due to high population of wild hogs which predate on the rattle snakes because of their sound.

Small amount of rattle snakes that lack the muscles to rattle so they don’t get predated on, survive and reproduce which has lead to a high frequency of rattle snakes to also lack those muscles.

Question 18

How does the the rattlesnake example in the previous answer illustrate natural selection and evolution?

Answer 18

1. Evolution operates on the population - no individuals ever lost its rattle and individuals do not evolve.
2. Natural selection operates on the individual where individuals survive and reproduce or they do not.
3. Variation had to be present in the population in the first place through genetics.
4. No such thing as an absolutely better variant as it depends on the environment.

Question 19

What is ‘soiobiology’?

Answer 19

Sociobiology applies evolutionary principles, specifically natural selection, to behaviour.

How behaviour might be naturally selected/adapted.

Sociobiology looks at how behavioural variations give individuals an advantage in survival and reproduction.

Question 20

Why was the topic of sociobiology controversial when it first surfaced?

Answer 20

When the topic first came out it was very controversial because it was taking away the concept of free will. Someone would do something bad but say it was outside of their control because it was genetic.

Overtime because of that backlash sociobiology was explained as how behavioural adaptations give individuals an advantage

Question 21

What are the 3 main ideas behind sociobiology?

Answer 21

1. Kin selection
2. Reciprocal altruism
3. Parental investment

Question 22

How did sociobiology come about?

Answer 22

altruism was observed in non-human primates and so sociobiology looked at how altruism could have evolved.

Question 23

What is the biological definition of altruism?

Answer 23

Behaviour that potentially improves survival and reproductive success of recipient while potentially endangering the actor.

Behaviour that benefits the recipient at a cost to the actor.

Question 24

What are some altruistic behaviours in humans?

Answer 24

Altruism started to be thought about due to the war. What made people sign up and go to war to fight for a concept they might not feel all that involved in.

Question 25

Give some examples of altruism in primates

Answer 25

• predator alarm calls
• helping another individual fight
• defending a group member from a predator
• feeding/caring for a baby

Question 26

Why is altruism hard to explain in terms of natural selection?

Answer 26

Because natural selection is a behaviour that increases survival and reproductive success which is passed on at a higher rate because the behaviour is favoured by natural selection.

A behaviour that decreases survival and reproductive success of the actor will not be favoured by natural selection so how could the behaviour of altruism be passed on through the principles of natural selection.

Question 27

What was the original theory behind the passing on of altruism?

Answer 27

Originally altruistic behaviour was thought to evolve “for the good of the group” (group selection) by (Wynne-Edwards, 1962).

Question 28

What were the problems with the theory of group selection?

Answer 28

Group selection was defined as natural selection acting on the group rather than the individual.

However, for it to work, groups with altruists would have higher fitness than those without. But altruists may have decreased reproductive success, while selfish individuals would have higher reproductive success.

So altruists would not be passing on their genes.

Group selection was rejected because evolutionary biologists could not see how it would work as natural selection only makes sense if it acts on the individual as each individual is striving to maximise their own reproductive success.

Question 29

What is the answer to how altruism could have evolved?

Answer 29

Through kin selection.

Question 30

What is kin selection based on?

Answer 30

That each individual shares genetic material with their relatives.

This means that even if an individual never reproduces, it is possible to have some of its genes represented in the next generation.

Question 31

What were the new important concepts introduced with kin selection?

Answer 31

Natural selection can operate on genes rather than individuals.

Introduced the concept of ‘inclusive fitness’. Individual fitness + effect on fitness of their relatives.

Question 32

What is some of the evidence for kin selection?

Answer 32

Members of a coalition formation tend to be related and grooming tends to happen between relatives as well as food sharing which is very rare.

Question 33

Does altruism ever occur between non-relatives?

Answer 33

Yes - altruism between non-relatives cannot be explained by kin selection but an alternative explanation for this is reciprocal altruism.

Question 34

Give an example of a study that shows reciprocal altruism

Answer 34

Frans de Waal TED TALK

video from nearly 100 years ago - two factors, fairness and compassion (pillars of morality)

Trained chimpanzees to cooperate. Box is too heavy for one chimp so they must work together to get to the food on top of the box.

One chimp has been fed so is less interested in the task. Chimp which hasn’t been fed must use gestures to keep the partner interested.

The fed chimp still cooperates with the partner although he’s been fed and there is no aggression when the fed chimp takes half the food at the end.

This is because they have an understanding that if they work well together now, the favour will be returned in the future.

Question 35

Give an example of how an individual could benefit from reciprocal altruism

Answer 35

Indiviuduals that participate in reciprocal behaviours are the ones that benefit more because they will be helped in the future. Food sharing is often targeted at those who are less healthy, possibly so if that actor is unhealthy in the future it will be fed by the others in the group in a reciprocal deal.

Question 36

Give the definition of reciprocal altruism and who discovered the principles of it

Answer 36

(Trivers, 1971)

• Helping behaviour between non relatives
• individuals help others to get help in the future when needed
• eventually the benefits to the individual will outweigh the cost

Question 37

When does reciprocal altruism work and not work?

Answer 37

Reciprocal atruism doesn’t work when the individual won’t see the recipient again. However this does work in kin selection.

When this happens and individuals aren’t related there must be sociality, with repeated interactions.

Altruism will normally take place with members of similar fitness, if they are of low fitness then they must have another ability that is worth the support.

Question 38

What is meant by “cheaters” in terms of reciprocal altruism and what is the disadvantage of this behaviour?

Answer 38

Cheaters are those that take help without reciprocating.

However, individuals are soon identified and they will stop receiving aid from others.

‘Cheater’ behaviour doesn’t evolve because their fitness suffers due to being found out. It doesn’t lead to the disappearance of altruism.

Question 39

Does “helping” behaviour ever occur between non-kin without evidence of reciprocal altruism?

Answer 39

Yes, these types of behaviours could also evolve through MUTUALISM.

This is not a tenancy of sociobiology

Question 40

What is mutualism?

Answer 40

This is an interaction between two organisms where each gains a fitness benefit.

This behaviour can look like cooperation but is not considered as altruism as there is no overall cost to the actor in helping.

Question 41

Give an example of mutualism

Answer 41

Two males in a coallition could be seen as mutalistic. Both defeat an alpha meal so both get access to females, or find a new food patch together, they can both feed there.

But no cost to the actor so it is not altruism.