1. FURTHER STUDIES OF BEHAVIOUR
AHL Option E.6
IB Biology
Miss Werba

2. OPTION E - NEUROBIOLOGY
STIMULUS and RESPONSE
E.2
PERCEPTION of STIMULI
E.3
INNATE and LEARNED BEHAVIOUR
E.4
NTs and SYNAPSES
E.5
THE HUMAN BRAIN
E.6 FURTHER STUDIES IN BEHAVIOUR
J WERBA – IB BIOLOGY 2

3. THINGS TO COVER Social behaviour Natural selection & social behaviour
Altruistic behaviour
Foraging behaviour
Mate selection
Rhythmical behaviour
J WERBA – IB BIOLOGY 3

4. SOCIAL BEHAVIOUR Command term = DESCRIBE
Social behaviour: behaviour directed towards, or taking place between, members of the same species
Examples:
Honey bees
Mole rats
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5. SOCIAL BEHAVIOUR Command term = DESCRIBE
Honey bees
Honey bees live in colonies of 20,000+ individuals
Individuals in the colony interact closely and have set functions and responsibilities.
These are referred to as castes.
Most individuals in the colony are workers and there is one queen.
There are also drones, whose only function is to mate with the queen.
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6. SOCIAL BEHAVIOUR Command term = DESCRIBE
Honey bees
Queen:
There is only one queen in each colony!
Function = to produce eggs
Only leaves the hive to mate and swarm
Controls colony activities through pheromones (scent)
Mates with many males at one time and stores sperm to be used throughout her life
Lays thousands of fertilised eggs in the cells of the honey comb
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7. SOCIAL BEHAVIOUR Command term = DESCRIBE
Honey bees
Workers:
All female
Non-reproductive
Perform a series of roles in order as they mature:
young bee, nurse, builder, guard, honeymaker
Live for ~30 days
Feed the queen and drones
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8. SOCIAL BEHAVIOUR Command term = DESCRIBE
Honey bees
Drones:
All males
Haploid (ie. only have one set of chromosomes)
Their only function is to mate
Mate with the queen in the air and die soon after
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9. SOCIAL BEHAVIOUR Command term = DESCRIBE
Honey bees
When the colony gets too big, the queen will prepare to leave
If this is the case, some of the larvae are fed a high protein diet  they will develop into queens.
Otherwise, they will develop into workers.
The old queen will leave with half the colony and the new queen will emerge.
The drones will follow the new queen. She will be fertilised and store the sperm to be used over the next few years.
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10. E.6.1
regulates activity
Drones
secrete pheromones
fertilise queen
clean hive
Honey bee colony
Worker bees
Queen bee
Young
3-5days
fed special diet
guard hive
Adult
21-40days
forage
Maturing
5-20days
build hive
leave hive
process honey
control Tº
feed larvae
Lays fertilised eggs
fed normal diet

11. SOCIAL BEHAVIOUR Command term = DESCRIBE
Naked mole rats
Mole rats live in underground colonies of up to 80 individuals
They are blind.
Individuals in these colonies also set functions and responsibilities.
There is one queen and a small number of reproductive males.
The queen is the only female who is allowed to mate.
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12. SOCIAL BEHAVIOUR Command term = DESCRIBE
Naked mole rats
Non-reproductive females act altruistically to promote survival of the queen and her offspring.
When the queen dies however, competition between females becomes fierce as the other females compete to take her place
The sterility of the workers is not genetic but maintained by the queen using pheromones.
The burrow itself could not be constructed or defended without social organisation. Either the colony as a whole survives to form new colonies or it doesn’t.
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13. NATURAL SELECTION IN A COLONY Command term = OUTLINE
A colony of individuals with set roles displays emergent properties.
Which means....???
That the whole colony is more than the sum of its parts.
All individuals are closely related genetically.
Advantageous traits in a caste that promote the reproductive fitness of the queen will be selected for.
These genes will be propagated through the species.
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14. ALTRUISTIC BEHAVIOUR Command term = OUTLINE
Altruistic behaviour: behaviour that benefits others and involves risk or cost to the performer.
Altruistic behaviour is the product of natural selection.
Innate behaviours are genetic and therefore subject to natural selection.
Examples:
parenting care by mammals
Ants
Vampire bats
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15. ALTRUISTIC BEHAVIOUR Command term = OUTLINE
Ants
Demonstrate altruism through kin selection, in a similar way to honey bees
They ensure that closely related individuals are promoted, thus ensuring the survival of shared genes
Males are haploid, females are diploid
Therefore all females are 75% genetically similar
By acting altruistically to defend the colony, raise the young or feed the queen, individual workers promote their own genes.
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16. ALTRUISTIC BEHAVIOUR Command term = OUTLINE
Vampire bats
Demonstrate reciprocal altruism
They ensure their own survival and reproductive success by helping another individual.
They need to feed on blood every 24-36hrs or they lose body weight quickly and can die.
They have a blood-sharing system, where unrelated bats share blood with each other.
Individuals who do not reciprocate are expelled from the sharing group and are therefore unlikely to survive should they need blood later.
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17. FORAGING BEHAVIOUR Command term = OUTLINE
Foraging behaviour: behaviour that allows for the collection of food that is available in nature, by gathering, fishing or hunting.
The benefit must exceed the cost.
As long as the benefit of energy outweighs the energy and time expended, the foraging strategy being used will benefit the individual’s reproductive fitness.
Examples:
Bluegill sunfish
Crown of thorns starfish
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18. FORAGING BEHAVIOUR Command term = OUTLINE
Bluegill sunfish
These fish live in ponds where they prey on small invertebrates, including Daphnia.
When food is scarce, the fish will consume all sizes of Daphnia.
When food is abundant, bluegills are more selective with their prey, choosing only larger Daphnia.
Consuming small numbers of large prey takes less energy than large numbers of small prey, so it represents a better benefit:cost ratio.
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19. FORAGING BEHAVIOUR Command term = OUTLINE
Crown of thorns starfish
These starfish live graze on coral polyps, the organisms that build coral reefs.
They will remain in an area for as long as it is beneficial to forage there, and then they move on.
This gives them a high benefit:cost ratio.
They are causing widespread damage to coral reef systems, each individual starfish clearing 6m2 of reef per year.
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20. COURTSHIP BEHAVIOUR Command term = EXPLAIN
Sexual selection or courtship behaviour: behaviour that results in mating and eventual reproduction, involving chemical, visual, or auditory stimuli.
Females often choose their mate
So males need to attract females in order to mate
Males may also need to fight other males to establish dominance
Example:
Peacocks
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21. COURTSHIP BEHAVIOUR Command term = EXPLAIN
Peacocks
The peacock tail is an exaggerated trait to attract females of the species.
They advertise reproductive fitness, but deliver it at a survival cost.
Mate selection can drive speciation between separated populations.
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22. RHYTHMICAL BEHAVIOUR Command term = STATE
Animals show rhythmical variations in activity.
These behaviours are innate, so they are subject to natural selection.
Rhythmical behaviour: behaviour and activities that change rhythmically (over regular time periods – eg. seasons, days, months).
Example:
Seasonal migration patterns of whales
Turtle nesting according to lunar cycles
Bee populations booming during spring
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23. Peacock spiders

24. Sample questions
Q1 (5 min)
Discuss the evolution of altruistic behaviour in a non- human species. [6]
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25. Sample questions
Q2 (8 min)
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26. Sample questions Q2
State the effect of the presence of the helpers on i. mean chick mass. [1] ii. the probability of survival of the breeding females until the next breeding season. [1]
Calculate the percentage decrease in mean egg volume found in the presence of helpers as compared to the parents only. Show your working. [2]
With reference to the data, suggest why the activity of the helper affects the probability of survival of the breeding female until the next breeding season. [2]
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27. Sample questions A1
altruistic behaviour may be harmful to the animal itself but beneficial to other animals;
occurs in social animals;
usually occur in the same species;
need not happen between genetically related animals from one population;
altruistic behaviour often occurs in animals which are genetically closely related;
altruistic behaviour may increase the survival rate of the group and thus the species;
helping close relatives or siblings increases the chances of passing on genes to the next generation;
due to natural selection;
this is called inclusive fitness;
enhancing reproductive success of relatives is called kin selection;
if altruism was a negative trait it would / may have disappeared;
altruistic species do just as well as non-altruistic species belonging to the same order; max
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28. Sample questions A2
i. (mean) chick mass increases in presence of helpers. [1] ii. female survival probability increases in presence of helpers [1]
( )/1300 * 100% = 5.8% (Accept the correct answer if it is not rounded up to 5.8% or if it is rounded up to 6%) [2]
with helper, smaller egg volume; less resources from mother to produce egg/rear young; more resources toward survival of mother [2]
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