2. Introduction to E.6
•Natural selection extended to
societies
•Consider selfish genes as the unit
of natural selection
•Advanced social structures are
based on kin selection
•Consider the game known as
the prisoner’s dilemma
3. The Prisoner’s Dilemma
Sells friend out (betrayal)
A Keeps quiet (cooperation)
Sells friend out
A is jailed for life, B
(betrayal)
Both are jailed for life
gets released
B
Both are jailed for a
(cooperation)
Keeps quiet
B is jailed for life, A
year and remain
gets released
friends :-)
4. Social structure of the eusocial Honeybees
• Honeybees organise themselves into the following
hierarchy
• Queen - Diploid, fertile, lays eggs, female (quite
obviously)
• Workers - Diploid, female, workers
• Drones - Haploid, male, useless except for sex
5. Social organisation of elephants
• The african elephant lives in herds or 10-20 females
• The herd is lead by a matriarch female
• Any calf may suckle on any nursing cow
6. Mathematics behind altruism
• Hamilton’s Law: rB > C
• r = relatedness between the recipient
and the altruist
• e.g. r = 0.5 between a parent
and a child
• B = reproductive benefit(s)
• C = reproductive costs
8. FORAGING BEHAVIOUR
• FOOD is essential (well duh)
• Advantage of foraging: gaining Calories
• Animals tend to optimise foraging
• Such that energy gained > energy spent
• Consider the cost-benefit analysis
9. Small-Mouth Bass
• The bass has two main food sources.
• Minnows - easy to digest, more energy/unit, more
difficult to catch
• Crayfish - more difficult to digest, less energy/unit,
easy to catch
11. Male Selection leads to Exaggerated Traits
•Consider the peacock
•Peacocks long tail = exaggerated so female picks = more
offspring but too much isn’t good = extreme = attract predator.
12. Rhythmical Behaviour Patterns
• Animals often show behaviour which appears rhythmic
• Daily patterns are regulated by biological clocks or external
environmental clues
13. Rhythmical Behaviour Patterns - Magicicada
• Some species emerges every 17 years,
Others every 13 years or 7 years
• Life is spent underground as a nymph,
with a few days after emergence as an
adult to breed
• Advantageous because of predator’s
inability to coordinate their own cyclic
behaviour to a prime number
14. Rhythmical Behaviour Patterns - Fiddler Crab
• Their courtship is based on the phases of the moon
• The lunar cycle determines the best tidal periods for the release
of crab eggs
• Advantageous because the crab eggs need the tide to be
transferred to the open ocean, where crab larvae thrive
17. 1. Describe a drone.
A drone is a haploid male honeybee that does
nothing but have sex with the queen bee.
18. 2. Give an example of altruistic behaviour that was
not discussed.
19. 3. In high prey density conditions, what size of
Daphnias do bluegill fish prefer?
20. 3. In high prey density conditions, what size of
Daphnias do bluegill fish prefer?
Large
21. 4. Identify one problem with altruistic
behaviour over evolutionary time.
22. 4. Identify one problem with altruistic
behaviour over evolutionary time.
The behaviour may linger on while its benefits may
no longer be there (e.g. dolphins helping whales,
our own tendency to donate to places like Africa)
23. 5. How is it that peacocks are able to survive
to lay eggs even with a tail that obviously
exposes them to predators?
24. 5. How is it that peacocks are able to survive
and lay eggs even with a tail that may expose
them to predators?
Lame joke
alert... only
peahens lay
eggs
