1. E6- Further Studies of BehaviourPp

2. Social Organization of the Honey Bee
Live together in groups of – individuals
There are three castes(i.e. there is division of labour):
Queen: fertile female
Lays eggs that hatch into larvae- if larvae are fed a special diet, royal jelly (more protein), they will develop into queens
Produce pheromones to regulate activities of the workers
Drones: fertile males
Workers: sterile females
Most bees are workers
infertile females

3. Bee Society
Drones only role is to mate with queen, which can lay 1500 eggs a day.
Drones are only tolerated during the spring and summer when the queen mates, and are driven out at other times.
Worker bees gather food, feed the queen, guard the colony, produce pheromones to help co-ordinate activities, feed larvae, secrete wax to build the hive and clean the colony.
Workers change duties as they age, about half life span spent on indoor duties, then rest of time outside foraging
When a new queen is needed, she hatches and takes her first flight, during which she is inseminated by several drones. She will then ‘swarm’ with members of the old hive and go establish a new hive.
honey bee biology

4. Social Organization of the Naked Mole Rat
Social structures are unusual for mammals:
Naked moles live in colonies underground
Only the queen will reproduce with a few males
Other females are workers- tunnelers, defenders, or food gathers
If queen dies the larger female workers will fight until it is clear who the new queen will be
The sterility of the workers is not genetic but maintained by the queen, possible using pheromones.

5. How Natural Selection act at the level of the colony in the case of social organisms:
Natural selection may act at the colony level rather than the individual level
Members of the colony work for the benefit of the colony & not for themselves
Co-operation of individuals ensures survival of the colony
The more efficient is the co-operation, the more likely the colony is to survive
Example, in naked mole rats:
In the case of food shortage a worker could feed the queen but starve herself
The queen and the worker are closely related so this behavior is likely to spread because the queen is likely to survive and pass on the genes that caused the workers behavior to the next generation.

6. Altruistic Behaviour

7. Altruistic Behaviour - Animation

8. Altruistic Behavior
Altruism- behavior which benefits others and involves risk or cost to the individual displaying the behaviour
(Note: IB does not consider parental care to be an example of altruism).
Example 1: Worker bee
Worker bees dies defending colony against attacking wasp- never reproduces only looks after the colony
Example 2: Vervet monkeys
monkeys give alarm calls when predator approaches
alarm calls attract attention of predator and others monkeys have more time to escape
closer the genetic relationship the less altruism involved
benefits increase over time through survival of genes shared with recipient
behaviour might lead to an advantage for the individual displaying behaviour in the future

9. Altruistic Behavior Cont…
Example 3: Vampire bats
Form social groups, colonies, of unrelated individuals
they feed on fresh blood from animals such as pig, cattle
if bats go without food for two days they can die of starvation.
If one bat doesn’t feed, another one which has fed will regurgitate food and share. This is done regardless of whether the bats are related or not.
A bat that has been fed in this way will give food another time
Why? “You help me now, and I’ll help you later”.
This is called reciprocal altruism

10. Explain the role of natural selection in the development of behaviour patterns
innate behaviour patterns are inherited
animals show variation in their behaviour
behaviour patterns are adapted to the environment
those animals with adaptive behaviour more likely to survive
animals which survive leave more offspring than those less adapted leading to change in allele frequency
population (species) starts to show more adaptive behaviour
thus the population has evolved

11. Evolution of Altruistic Behaviour
organism expends time & energy in caring for other unrelated members of the same species
such animals put themselves at risk or disadvantage for the good of other members of the species, such actions increase another individual’s number of offspring at cost to one’s own reproduction
close kin share alleles
the adaptive significance of altruism is to increase frequency of alleles shared in common by members of the species
altruism provides genetic advantages in kin by promoting survival and reproduction within species
altruistic behaviour towards non-relatives may allow selection of alleles responsible for the behaviour to be perpetuated
some argue no true altruism as organism benefits either directly or indirectly in the future - reciprocal altruism ?

12. Foraging Behavior
‘foraging’ refers to the processes of searching for, obtaining, and then consuming food.
food is generally rarely distributed uniformly, and when located, different sources may be of different qualities
consequently, foraging animals need to optimise the return on their investment of time and energy in obtaining food
natural selection will favour strategies that minimise the costs of the search and maximise the benefits
foraging Theory suggests that the food choice of the animal will maximise the energy obtained

13. Bluegill sunfish foraging for Daphnia
Bluegill fish and Daphnia
Fish will choose largest prey when given a choice.
In nature they choose the prey that appears the largest
When prey is abundant they choose the largest, when prey is scarce they choose one that may be smaller but is closer so appears larger.
More profitable to catch the closer than larger fish

14. Bluegill sunfish foraging Animation

15. In bluegill sunfish, Prey selection behaviour is related to prey density

16. Foraging by the honey bee

17. Foraging by the honey bee
Foraging for nectar and pollen is the chief duty of worker bees at a later stage in their working life.
First, individual worker bee surveys for feeding sites & report back to the main body of workers in the hive.
Through waggle dance, worker honey bee communicates the location of new food sources to the other workers in the colony
the waggle dance optimises food intake by the hive community

18. Mate Selection and Exaggerated Traits
in animal species that reproduce sexually, the quality of the mate may be critical to reproductive success
animals seldom mate indiscriminately – various mechanisms ensure some selectivity in the sexual process
sexual selection is the struggle between individuals of one sex (usually males) for the possession of access to individuals of the opposite sex.
the outcome for a loser of this struggle is few or no offspring
victory in the struggle may depend on the use made of special features of structure or behaviour which are genetic
the long-term outcome has been the evolution of exaggerated traits that draw attention to a potential mate and markedly increase the possibility of reproductive success.

19. Mate Selection and Exaggerated Traits:
Females choose their mates:
Ones with best genes
Ones with ornaments (easier for predators) must have good genes to survive
Males need to attract mate:
Must have something that grabs her attention
Males may fight for dominance:
Dominant male reproduces
Both males may get harmed during the fight

20. Rhythmical variations in activity in animals
rhythmical behaviour patterns are common in animals
they including daily (circadian) & annual rhythms
these patterns have adaptive value, – aiding survival of the organisms concerned
circadian rhythms; animals are active for only a part of the 24-hour cycle
annual rhythms; animals produce young ones in a season favourable for rearing and feeding

21. Rhythmical Variations
Daily or yearly changes in activity
Hummingbirds- slow down metabolism at night in order to save energy and egg-laying in spring
Value of Rhythmical Variations:
Coral- Mass spawning at same time for males and females- best chance of reproduction
Deer- fertile period is in November so babies are born in spring
Roe deer- fertile in summer when healthy and the embryo “floats” in the uterus and has little growth until December when it attached and has normal growth

22. Revision Questions
Describe the social organization of honey bee colonies.
Outline how natural selection may act at the level of the colony in the case of social organisms.
Discuss the evolution of altruistic behaviour using two non-human examples.
Outline two examples of how foraging behaviour optimizes food intake
Using two named examples, outline a rhythmical behaviour pattern with an adaptive value.
Explain how mate selection can lead to exaggerated traits