Transcript Further Studies of Behaviour - IBDPBiology-Dnl

Pp 499 - 505
Social Organization of the Honey Bee
 Live together in groups of
20 000–80 000 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
Bee Society
 Drones only role is to mate with queen,
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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
Social Organization of the Naked Mole Rat
 Social structures are unusual
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for mammals:
Naked moles live in colonies
underground
Only the queen will reproduce
with a few males
Other females are workerstunnelers, 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.
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.
Altruistic Behaviour
Altruistic Behaviour - Animation
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
Altruistic Behavior Cont…
 Example 3: Vampire bats
 Form social groups, colonies, of
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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
Explain the role of natural selection in the
development of behaviour patterns
 innate behaviour
 animals which survive
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
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
Evolution of Altruistic Behaviour
 organism expends time & energy in caring for
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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 ?
Foraging Behavior
 ‘foraging’ refers to the processes
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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
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
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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
Bluegill sunfish foraging Animation
In bluegill sunfish, Prey selection behaviour is
related to prey density
Foraging by the honey bee
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
Mate Selection and Exaggerated Traits
 in animal species that reproduce sexually,
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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.
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
Rhythmical variations in activity in animals
 rhythmical behaviour
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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
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
Revision Questions
 Describe the social
 Outline two examples of
organization of honey
bee colonies.
 Outline how natural
selection may act at the
level of the colony in the
case of social organisms.
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
 Discuss the evolution of
altruistic behaviour
using two non-human
examples.