Transcript further studies in behaviour

Further studies of behaviour
HL only
E.6.1 Describe the social
organization of honey bee
colonies and one other nonhuman example
Studies innate in nature
• Automatic responses to stimuli which
are controlled by genes and are
therefore subject to natural selection
• Populations tend to produce more
offspring than the environment can
support
• Variations within populations can be
selected for or against
• INNATE BEHAVIOUR become
optimised over time
The Secret Life of Honeybees
Live above ground trees
Make wax combs –
store honey
Cells storing honey &
rearing young
• Queen
• Workers
• Drones
Lay eggs
Sterile
female
Males for
mating
All female, nonreproductive
Go through series
of roles in order:
young bee, nurse,
builder, guard,
honeymaker
Live for around 30
days
Feed queen and
drones
Drone
Workers
Queen
Produce eggs
Flies only to mate
& swarm
Controls colony
activity by scent
Mates with many
males at one time
& stores sperm
Lays thousands of
eggs
Cuts down on egg
production if food
supplies are
scarce
Haploid males
Only function is to
mate
Mate in the air
and die soon after
Bee organization influenced by diet
• Unfertilized eggs = male no matter
what they eat
• Fertilized eggs + type of food = queen
or worker
• Larvae fed royal jelly first few days
– Then switch to pollen + honey = workers
– Royal jelly continues = new queen
Control with phermones
• Inhibit ovarian
development in
workers
• Workers lick it off
queens body while
eating & pass it to
other workers
Bee communication
• Chemical in tip of abdomen is used to
identify the source of nectar or water
• Some bees scout, find nectar and do
a waggle dance – direction & distance
• Chemical from the mouth identifies
danger to the colony
Social organization - chimps
• Work of Jane
Goodall – ethologist
• Community – highest
order
– 40-60 members
– Party
•
•
•
•
•
Up to 5 members
May be all males
A family unit
Nursery unit
Depends on food
supply
Social hierarchy
• Highest = male, age 20-26
– Dominance determined
• physical features
• Fighting ability
• Females = linked with age
• Males have strong social bonds
– Related to each other
– Stay in same community
– Females may migrate
Roles
• Male bonding leads to cooperative
behaviour
E. 6. 2 Outline how natural
selection may act at the
level of the colony in case of
social organisms
Natural Selection at the colony
level
• It would seem worker bee behaviour would
not be promoted by natural selection
• Natural selection = most well-adapted
worker will survive & reproduce
• However, workers don’t reproduce
• The gene causing the behaviour of the
worker should be eliminated from the
population
Natural Selection – colony level
• Natural selection is acting on the
colony as a whole
• Genes selected for:
– Promote social organization
– Pheromones to control the behaviour of
workers
– Behaviour of finding nectar and making
wax
By chance who
– Taking care of the young gets fed the
royal jelly
Naked Mole Rat: colony living
• Heterocephalus
glaber
• Blind
• Underground
colonies
– One queen
– Small number of
reproductive males
– Others don’t mate
Naked Mole Rats
• Intraspecific competition is fierce and
bloody when the queen dies.
• Other females compete to take her
place
• Social status depends on
reproductive ability
• Non-reproductive individuals act
altruistically to promote the survival
& reproductive fitness of the queen
and her offspring
Natural Selection at the colony level
• A colony of
individuals with set
roles (castes)
displays emergent
properties
• A whole of a
colony is more that
the sum of its parts
E.6.3 Discuss the evolution
of altruistic behaviour using
two non-human examples
Altruistic Behaviour
• Promotes the
reproductive
fitness of another
individual at
considerable cost
to oneself
Honeybee guards sacrifice
their own life for the colony’s
survival.
How has altruism evolved?
Kin
selection
Reciprocal
altruism
• Closely related individuals
are promoted thus
ensuring the survival of
shared genes (decrease in
fitness of the altruist)
• Helping another may be
returned in the future,
ensuring the survival of
oneself and thus aiding
reproductive success
Kin Selection
Ant Colonies
Males
are
haploid,
females
are
diploid
Diploid
females
are 75%
similar
genetically
(chromosomes
from males are
not subject to
independent
assortment,
therefore are all
identical)
Animal communication
I am mostly likely
going
to be killed
Kin Selection
• Naked Mole Rats
– Main predator –
snakes
– Snake attack
• Queen sends
workers to attack
snake
• Workers sacrificed
so queen and
young live
Reciprocal Altruism
• “You scratch my
back, I’ll scratch
yours”
Vampire bats
• Hematophages
– Feed on 50% of their body weight every 2436 hours
• Blood-sharing
– Unrelated bats can
share blood
– Typically between
females
– Ensures survival of
own offspring if
needed
one’s
E. 6. 4 Outline two
examples of how foraging
behaviour optimizes food
intake, including bluegill fish
foraging for Daphnia
Foraging – the act of searching for,
chasing, capturing, killing & consuming food
Benefit
• Foraging results in
food; a benefit in
terms of energy
Cost
• Foraging takes energy;
there is a cost in terms of
time and energy
Cost-Benefit Analysis
• As long as the benefit of energy
outweighs the energetic and time
cost expended, the foraging strategy
has a positive impact on the
individual’s reproductive fitness
• If a foraging strategy has an overall
cost, it will harm the individual’s
reproductive fitness – and therefore
have a deleterious effect. It will likely
be lost through natural selection
Optimal foraging
Bluegill
Optimal Foraging
Acanthaster planci
Crown of
Thorns
starfish
Widespread
damage to
coral reef
ecosystems
Eats coral
polyps
Patch
residence
time
E.6. 5 Explain how mate
selection can lead to
exaggerated tails
Mate Selection
Small
Tail
Large
Tail
Healthiest bird
Size Matters
Mate Selection
• Females will select mate based on
exaggerated trait
• Exaggerated trait = advertisement of
reproductive fitness, not adaptation
for survival
• Subject to natural selection bc. they
are physical or behavioural and
genetic in nature
Mate selection
• Competition between males for
mates can be fierce
• Through decent with modification,
these traits become ever more
elaborate and attractive
• Can drive speciation
E.6.6 State that animals
show rhythmical variations
in activity
Rhythmical Behaviour
Seasonal
Changes
Daily
(Circadian)
changes
Monthly (lunar)
changes
• Seasonal phenotypes
• Changes in day length, food
availability, etc
• Strong, indogenous component
• Exogenous cues are important
• Phases of the moon – light intensity
• Tidal rhythms
E.6.7 Outline two examples
illustrating the adaptive
value of rhythemical
behaviour patterns
Rhythmical Behaviour
Once a year, coral release millions of gametes in a
synchronized mass spawning ritual. Exact cues
are unknown (water temperature, lunar cycle,
hours of daylight?)
Lunar cycles
Synchronized nesting – leads to increase chance of
survival of hatchlings
Lunar Cycles
• Lunar cycles control turtle migration
• Mass egg laying at high tide between
last and first quarters of the moon
• Tide is weakest
• Less egg exposure to predators
Seasonal Behaviour
• Remember how photoperiodism
controls flowering in angiosperms?
Well, think up the food chain.
• Seasonal behaviour includes:
–
–
–
–
Waking from hibernation
Reproductive seasons
Migration
Spawning seasons
Climate change impacts
seasonal cycles
• Patterns of behaviour are
innate in nature and thus subject to
natural selection
• Cycles have been optimized through
evolution, with some small variation
within populations
• Climate change has a negative effect
on temperature and coincides with
food or resource availability
Circadian Rhythms
• Internal ‘Body Clocks’
• Influenced by light-dark cycles
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–
–
Genetic in nature
Optimized for 24 hour dark-light cycles
Healthy function of metabolism
Sleeping/feeding patterns
Circadian Rhythm