Social Behavior

1
Social Behavior
2
Animals that live in groups are called SOCIAL
ANIMALS
When members of the group interact, they are
showing SOCIAL BEHAVIOR
3
Adaptive value of social behavior?

• Coherence, cooperation and division of labor
  (specialization) within the group increases the
  chance of survival and reproductive success by

1. Better defense against predators (cooperation)
4
2. Sharing the work of rearing young
(specialization)
Production of an ant hill for reproduction and
raising offspring requires cooperation between
all ants in the colony
Worker honey bees feed and care for young of the
colony
5
3. Food-finding (cooperation or specialization)
6
The degree of social interaction differs among
different species of animals
Naked Mole Rat
Some species form loose groups with limited
social interaction (ex. lemmings).
Chimpanzees
Termite mound
Other species form groups that are highly
organized.
Honey Bees
7
Social behavior in Honey Bees is highly organized

• The Caste system is when a society has distinct
  groups in the population that are designed for a
  particular role.

Termites, ants and honey bees have a caste system
which results in great efficiency in food
collection, reproduction and child rearing.
The Summer of June - A Story of a Honey Bee.
8
The social organization of honey bee colonies
Bee basics
Collects pollen and nectar Converts pollen into
honey Secretes wax and builds comb Feeds and
looks after larvae Guards the hive
Mates with virgin females
Lays eggs Produces a pheromone to control
activities of workers
9
The queen is the largest bee in the colony and is
the only sexually developed female in the hive.
A two-day-old larva is selected by the workers to
be reared as the queen. She emerges from her cell
11 days later to mate in flight with about 18
drone (male) bees. She receives several million
sperm cells which last her entire life span of
nearly two years.
She begins laying eggs about 10 days after
mating. A productive queen can lay 3,000 eggs in
a single day. 
10
Drones are stout male bees that have large eyes
and no stingers. Drones do not collect food or
pollen from flowers. They lead a life of leisure,
doing no work while being fed by the workers.
Their sole purpose is to mate with a queen,
thereby transferring the genetic traits of their
mother. They die upon mating, or are expelled
from the hive as winter approaches.  
11
Bees fanning
Gathering nectar
Workers, the smallest bees in the colony, are
sexually undeveloped females. The life span of a
worker bee is about 28 to 35 days. Workers that
are reared in September and October, however, can
live through the winter.
Workers feed the queen and larvae, guard the hive
entrance and help to keep the hive cool by
fanning their wings. Worker bees also collect
nectar to make honey and produce the wax comb.
12
Communication is important in a social group!!
Worker honey bees communicate by performing
dances. The dance performed indicates the
direction and distance of a good food source.
Waggle Dance
Round Dance
video
13
The Round Dance
The Figure Eight or Waggle dance
Indicates a food source less than 90m away
Indicates a food source more than 90m away with
direction
14
Waggle dance

• Two components of the waggle dance
• Straight run which indicates the direction of
  the food according to the angle of the waggle run
  on the vertical surface. If the bee waggles
  directly up the surface, then the food source is
  directly toward the sun. If the bee waggles
  directly down the surface, then the food source
  is directly away from the sun. If the food source
  was located 90 degrees to the right of the sun,
  the bee would waggle 90 degrees to the right.
• the speed at which the dance is repeated
  indicates how far away the food is

Bee Dance on You tube
15
Naked Mole Rats have an Organized Social Structure
Watch the video The Trials of Life Living
together and/or the You Tube videos listed below
and describe the social organization of mole rats
Link to Living Together
Animal Sex Naked Mole Rats Mantis
http//www.youtube.com/watch?v_C6a4ZTWDXk
Living Life Naked http//www.youtube.com/watch?
vNS7EGTJh7QUfeaturerelated Naked Mole Rats
by Oregon Zoo http//www.youtube.com/watch?vCvey7
1Feu0Efeaturerelated
16
Naked Mole Rat
Naked mole rats in East Africa live in burrow
systems, in communities with different castes.
One dominant female rat acts like a queen bee.
She is the only one to reproduce.
Frequent Workers dig tunnels and gather food.
Infrequent Workers occasionally help with heavy
tasks. They are larger than frequent workers.
Non-workers live in the central nests caring for
the queen and the young. They defend the colony
if necessary
17
Why have a social hierarchy?(adaptive value)

• It decreases the amount of individual aggression
  associated with feeding, mate selection and
  breeding-site selection.
• It ensures that resources are distributed so that
  the fittest survive.

18
Altruistic Behavior
Any animal behavior that is harmful to the animal
that displays it but helpful to another animal.
A behavior that reduces an animals individual
fitness but increases the fitness of the
recipient of the behavior.
Example A worker bee that dies while defending
the colony from an invading wasp
Example A worker bee that feeds the queen bees
larvae
Parental care is not considered altruism because
the survival of the DNA of the parent is being
aided.
19
What is the adaptive value of altruism?
Behaviors evolved because they have a
reproductive advantage
Natural selection is the process in which some
organisms live and reproduce and others die
before reproducing. Some individuals survive and
reproduce because they are better suited to
environment and their genes are perpetuated in
the gene pool.
What is the reproductive benefit of altruism?
2 theories
Kin Selection
Reciprocal Altruism
20
Alarm Calling in Belding's Ground Squirrels

• These calls make the animal
• more noticeable to predators.
• Adult and one-year-old female Belding's ground
  squirrels are much more likely to give alarm
  calls than males (who disperse away from their
  kin), and female squirrels with nearby kin are
  more likely to give alarm calls than those
  without living kin nearby. In addition, the
  chance that females will give alarm calls
  increases with age.

21
Vampire Bats

• 33 of young bats under 2 years old fail to get
  blood on any particular evening

There is a chronic threat of starvation among
vampire bats since they can only survive 3 days
without a meal
Successful bats will regurgitate part of their
blood meal for group members that were not
successful
22
An example of Interspecies altruism!
Read the article Biological Altruism first
published Tue 3 Jun, 2003 and explain how
altruism may have evolved in honey bees and
vampire bats.  
23
Kin Selection
Individuals help relatives because they share
genes. By helping relatives individuals are
helping perpetuate copies of their genes.
Naked Mole Rat
The non-reproductive individuals may sacrifice
their own lives to protect the queen because they
share genes.
24
Reciprocal Altruism
An apparently altruistic behavior performed with
the understanding that the recipient will
reciprocate at some future date.
Exchanging altruistic favors in such a way that
each individual has a better chance of survival
from cooperating than it would from failing to
cooperate.