HL-E6 Further Studies of Behavior • Describe the social organization of honey bee colonies and one other non-human example. • 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, including bluegill fish

foraging for Daphnia. • Explain how mate selection can lead to exaggerated traits. • State that animals show rhythmical variations in activity. • Outline two examples illustrating the adaptive value of rhythmical behaviour patterns.

Social organization in animals

• Some animals live in a community which are differentiated for different tasks. In other words there are division of labor and hierarchy.

Honey bee community

• There are 20 000 - 80 000 bees in a colony• There are three different bees

- a reproductive female (the queen), -many thousands of sterile females (workers),-a few hundred fertile males (drones)

Queen bee(2n)

meiosis

Eggs (n)

Haploid development- PARTHENOGENESİS

Drone bee(n) - male

Sperms (n)

mitosis

FERTILIZATION

Zygote (2n)

Queen-female

Worker-female

Workers• Workers survive for about six weeks, and they

undertake a sequence of duties in the colony.

1- First they are nurse bees tending to the growing larvae and building fresh comb cells.

2- Later they become outside workers, surveying for feeding sites, communicating about new food sites to other workers,

3- Guarding the hive entrance, and foraging for water and food.

Drones

• Drones survive for about five weeks. They do not work in the hive, but when a new queen leaves the hive they accompany her, compete to mate with her, and then they die.

Baboons

• They live together. • Individuals are stronglyemotional and highly motivated. • Grooming develops and reinforces social bonds. • Individuals protect themselves by mutual alarm

systems. • Once an individual becomes isolated from the

group, the chances of death are high.

Natural selection

• If baboon individuals are not in the troop they are lost with their genes.

• Individuals who can live with others they survive and their genes are naturally selected.

• Workers bees work for the benefit of other bees only (altruistic tendency).

• Survival of the whole colony and the reproducing members are depend on the workers.

Altruistic behavior

• Altruistic behavior reduces the survival chance of the individual but increases survival chances of the others.

Example: worker bees, kin-directed altruism: self-sacrificing behavior reciprocal altruism: all individuals in the group

aid and support each other (You scratch my back and I’ll scratch yours).

Vampire Bats• They live in social groups, colonies of unrelated individuals.• Nocturnal feeders on fresh blood from animals (horses,

cattle..)• The chance of failing to feed successfully is high.• If a bat fails to feed two consecutive nights usually die.• If a bat returns to colony hungry, the unrelated bats feed it.• A bat that has been fed in this way will give food at another

time. • This is called reciprocal altruism.

Foraging behavior and food intake

• The waggle dance of a worker honey bee is the way it communicates the location of new food sources.

Bluegill sunfish foraging for Daphnia

• When there are more Daphnia bluegill sunfish eat big size daphnia, even though they have to find them.

• When there are less Daphnia they eat small size and big size Daphnia.

Mate selection and behavior traits

• 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.

• Horn of deer• Feathers of peacock• Pheromones• Color changes

Rhythmical variations in activity in animals

• Circadian rhythms (daily)Diurnal, nocturnal, crepuscular (at dusk or

dawn)• Annual rhythms (migration, hibernation,

reproduction)

What is the adaptive value of this behavior pattern?