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E.6.1. Describe the social organization of honey bee colonies and one other non-human
example.
Social Organization of Honey Bee Colonies
Social Behaviour: two or more animals interacting with each other
Honey bee colonies are an extreme example of sociability where honey bees live in a very
complex colony of up to 60 000 members. Living as a “super organism that lives or dies
together,” not one bee can survive without the others. Honey bees nest above ground in a hive
with wax combs consisting of individual compartments where they serve two functions:
 Storing the honey
 Rearing their young
Within this environment, there are three social castes of honey bees, each with different, but
necessary tasks. These include:
Caste
Gender
-
Queen
Fertile Female
-
Workers
Infertile Female
-
Drones
Fertile Male
(from an unfertilized
egg)
Tasks
as the only fertile female, lay
eggs and reproduce
controls the hive with
pheromone secretions, which
inhibit ovarian development in
females
jobs: searching and collecting
for nectar and pollen, making
wax and honey, and feeding and
protecting the young larvae, and
guarding the hive
all jobs needed to maintain the
function of the colony = carried
out by the workers
mate with the queen or virgin
females destined to become
future queens, and successfully
reproduce and spread the genes
of the colonies to new ones
Furthermore, honey bees have an intricate system of communication. These include:
1. To identify source for nectar and water to the rest of the hive – a chemical
secretion from the tip of the abdomen is released. Some honey bees are even
assigned to scout out nectar and the location is then told to the rest of the workers
by a waggle dance to indicate the direction and distance of location
2. When in danger – another chemical is secreted from the mouth area and is then
spread to the rest of the colony
Social Organization in Chimpanzees
Ethologist: a scientist who studies behaviour in the wild (i.e. Jane Goodall)
Community: - the highest order of the chimpanzee society
- 40-60 members
Party: - a smaller group within the community
- up to 5 members (i.e. all male, a family unit, or a nursery unit or other combination of
individuals)
- the makeup depends on the food supply (more food = larger groups)
Hierarchy: social organization of chimpanzees
Male
Female
- highest ranking male is usually aged 20-26
- power determined by age (older ones are
- power determined by physical fitness and
more powerful than the young)
fighting ability
- females may migrate to other communities
- dominant over females
- responsibilities:
- stays in the same community in which they
- parental care
were born, resulting in strong social
- providing food, warmth and protection to
bonds
the young
- cooperative behaviours needed for:
- teaching the young
- keeping out intruders
- hunting
- sharing food
Facial expressions and vocalizations are used for communications
Social organization of Lions
Pride: a group or family of lions
Coalition: a group of 4-5 male lions that replace the male lions in a pride to mate with
the females and protect the offspring. Lions live in prides of about 1-4 males and 15
lionesses.
Males
- leave the pride between 3-4 years of age
to form their own coalition.
- the coalition try to take over another pride
but the lions that belong to that particular
pride fight back.
- In case of defeat, lions never return back to
the pride.
- have an average life expectancy of about 2-4
years.
- protect cubs and females from other male
lions.
Females
- stay with their own pride as their early
generations
- protect their cubs (under two years old) from
the new males who take over pride.
- Hunt food for themselves as well as their
cubs.
- a life expectancy higher than the male
References
 Shelburne, D. (n.d.). African Lion Social Organization -- David Shelburne. Biology
Davidson. Retrieved November 25, 2009, from http://www.bio.davidson.edu/people/vec
ase/Behavior/Spring2004/shelburne/organization.html
E.6.2 Outline how natural selection may act at the level of a colony in the case of social
organisms.
Natural Selection
• Natural selection is the theory of evolution proposed by Darwin based on the principle of “the
survival of the fittest.”
• Individuals who possess the favored phenotype to adapt to their environment will survive and
reproduce, passing their genes on to the next generation.
• These alleles accumulate in the gene pool of a species over generations increasing their allele
frequency.
Natural Selection in a Colony

In a honey bee population, the behavior of the worker bees should not be maintained
through natural selection because they do not reproduce. Therefore, the alleles that cause their
behaviour should be eliminated from the gene pool.
o However, this is not the case, as in social organisms natural selection acts on the
colony as a whole.

The genes selected are used for social organization, not just reproductive success.

For the honey bees, genes that control the behaviour of workers are selected including
genes for finding nectar, making wax and taking care of the young.

So it is the worker genes in the queen that keep the colony functioning while the workers
look after the survival of their own genes.
Zainab Al-Abd, Rabia Soni, Clarize Virtusio
Ms. Jackson
SBI4U7
November 24, 2009
E.6.3 Discuss the evolution of altruistic behavior using two non-human
examples.
ALTRUISTIC BEHAVIOR:
Performer behavior that benefits recipient relatives at the cost of the performer
-
Altruistic behaviour is often dependant on inclusive fitness refers to an organism's
classical fitness (how many of its own offspring it produces and supports) plus the
number of equivalents of its own offspring it can add to the population by supporting
others (Queller et al., 2002)
KIN SELECTION AND INCLUSIVE FITNESS:
- Fitness of any allele includes the fitness of identical alleles in organisms who are related.
- In terms of alleles, multiples of that allele in the next generation is success. Whether this
success comes from the organism itself or a relative is of no importance. (Queller et al.,
2002)
Hamilton's Rule:
If the benefit of the individual multiplied by the degree of relatedness to the donor is
greater than the cost to the donor, the behavior will be spread by natural selection.
rB – C > 0
 Animals are more likely to perform altruistic acts that benefit those who they are
closely related to. (Hamilton’s Rule)
EVOLUTION OF ALTRUISTIC BEHAVIOR IN NON-HUMANS:
According to Richard Dawkins, author of The Selfish Gene, altruism is actually selfishness by a
gene. (Fehr, 2005)
Example: The Silver-Backed Jackal also known as Canis mesomelas (Zabel, 2008).
1. The young males 'altruistically' assist their parents in creating family rather than
starting their own families if and when territory is not available
2. Increases helper's inclusive fitness from an allele perspective, more of them passed
off into the next generation either from themselves or from relatives are equal
amounts of success.
3. Parents (recipient) provide food and grooming whereas performer (donor) gains
parenting skills. (Zabel, 2008)
Another example:
Elephants risk their lives to save their offspring. Their offspring contains ½ of their mother’s
genes
Why do mothers protect their offspring? This is because for every altruistic behavior they are
doing which is protecting their offspring, they increase their fitness.
o Cost = risk of performing the altruistic behaviour
o Benefit= increased fitness form performing the behaviour
→ So, if the mother elephant dies in the altruistic act the cost was = 1.0
→ But if two of her offspring (2 x ½ her genes) are protected in the process then, the risk was
justified. (Click4Biology)
Reciprocal Altruism: assistance to non-familial organisms at a cost to the performer. This is
done with the assurance that the act will be reciprocated should the need occur.
Side blotched lizards are an ideal example. There are three different throat
coloured lizards including: orange, yellow and blue. The orange coloured lizards
tend to demonstrate extreme signs of aggression and are known to steal the territory
of other lizards, while the yellow throated lizards will sneak in to the territories of
other lizards and mate with females or males of the other lizards.
Blue throated males form partnerships in order to defend their territory. In most
cases, the orange throated wizards will defeat the blue throated lizards, which will in
turn defeat the yellow throated lizards. However, the yellow throated lizards tend
to avoid confrontation with the orange throated lizards and will generally sneak in
and breed with the orange throated females. Consequently, the blue throated
lizards often benefit from this mutual relationship as a deficiency in orange throated
lizards will allow them to reproduce more offspring. However, when there are
excess orange throated lizards, one of the blue throated lizards may spend a great
deal of time defending his territory whereas another blue throated lizard will have a
great deal of time to reproduce. During this situation, the relationship between the
lizards is altruistic as it does not benefit all of the blue throated lizards. This
behavior, exhibited by the lizards, is in some instances mutualistic and at other times,
altruistic.
Works Cited
Click4Biology. (n.d.). Click4Biology. Retrieved
http://click4biology.info/c4b/E/E6.htm
November
25,
2009,
from
Fehr, E. (2005). Human Altruism – Proximate Patterns and Evolutionary Origins. Analyse
& Kritik, 1(27), 6-47. Retrieved November 24, 2009, from http://www.analyse-undkritik.net/2005-1/AK_Fehr_Fischbacher_1_2005.pdf
Hamilton's rule. (n.d.). brembs.net: Research on Learning, Memory and Evolution.
Retrieved November 25, 2009, from http://brembs.net/hamilton/
Queller, D.C. & Strassman, J.E. (2002) Quick Guide: Kin Selection. Current Biology, Retrieved
November
24,
2009,
from
http://www.ruf.rice.edu/%7Eevolve/pdf/20002001/CurBio2002_12_R832.pdf
Zabel, C. (2008, Fall). Reproductive Behavior of the Red Fox. US Forest Services, 1, 10-43.
Retrieved
November
25,
2009,
from
http://www.fs.fed.us/psw/publications/zabel/zabel_thesis.pdf
Prakash Amarasooriya & Jonathan Cheung
SBI4U7
Ms. Jackson
November 24, 2009
Option E Presentation – E.6.4 Foraging Behaviour
All info with * beside it  info is not from click4biology, but from another source
E.6.4 Outline two examples of how foraging behaviour optimises food intake,
including bluegill fish foraging for Daphnia.
Foraging  finding food (necessary for survival and reproduction). What about optimal foraging strategies?
*One area cannot hold too many predators at once, since pop’ns of prey would decrease too quickly (bad for predators)
Natural selection favours strategies that minimise the costs of the search and maximise the benefits.
1. Cost = energy used to pursue, capture and consume the food.
2. Benefit = energy from the individual food item.
Foraging Theory  animal will search for food that will maximise the energy obtained
 Example 1: Bluegill Sunfish (Lepomis macrochirus) and their prey, Daphnia (water fleas)
*O’Brien, Slade, & Vinyard (1976)  if given a choice, fish would seek largest prey
*Found that the fish preferred larger prey (more food and energy), but if catching such large prey required swimming
longer distances, would find it more profitable to catch several smaller prey instead
*Kolar & Wahl (1998)  presented bluegill sunfish with 2 different species of daphnia: D. lumholtzi and D. pulex
*Observations: more D. pulex eaten than D. lumholtzi when offered each separately; only D. pulex eaten when both offered
*Explanation: D. lumholtzi harder to eat (large helmet, long tail) esp. by smaller fish  selection against eating
D. lumholtzi allows fish to eat more prey (D. pulex) in same amount of time (optimization of food intake)
Werner and Hall hypothesized that: Blue gill fish will, if the prey availability is
altered, change their feeding choices to maximise the energy benefits and reduce
costs.
Cost-benefit analysis:
1) energy content of different sized water fleas
2) time and energy required to capture the different size of water
3) how often prey are encountered under different densities of water fleas
Independent variable = different densities of prey with different ratios of
daphnia
Dependent variable = selection of prey during the three different trials
The daphnia were set up at three different densities.
Results:
High density  preferred prey were large daphnia, although some medium and small prey were still selected
Low density  little variation between prey sizes selected
Results show evidence that bluegill sunfish has foraging strategy which allows it to change its hunting behaviour in short
term, according to food supply change.
 Example 2: The Northwestern Crow (Corvus caurinus)  from British Columbia
Optimal Foraging Theory  benefits of feeding behaviour exceed the energy costs
Choice of prey: Whelk (a species of gastropod)
Crows eat whelks by first breaking shell  drop them from a height onto the
rocks below (fun fun fun)  shell breaks: eat… shell intact: drop again…
Flying to drop the shell costs energy & detracts from benefit of the food value.
Researchers dropped whelks form different heights to break their shells.
By recording the height of the drop and the number of times required to drop the shell to break,
they calculated how high the crow needs to fly on average to break the shell and how much energy it must invest.
Results: Optimal height (req’d least total height) for the experimental shell breaking = 5 metres.
Crow observations: maximal foraging strategy with preferred drop height of 5.23 m.
Conclusion: This result has a very close approximation to the predicted 5 m, therefore crows optimised their foraging
behaviour.
 *Example 3: Black-capped chickadee (from northern USA and Canada)
*Krebs et al (1974)  simulated natural setting by putting different #s of mealworms on pine cones for the chickadees.
*The chickadees would fly elsewhere if they did not successfully find enough food after a certain period of time.
*This shows that the birds will not waste time searching fruitlessly for food by moving quickly to another area, increasing
chances for better foraging.
Works Cited
Burrell,
J.
(2008).
Click4Biology:
E6
Further
Studies
of
Behaviour.
Retrieved
from
http://click4biology.info/c4b/E/E6.htm#4
Weem, M. P., Talbot, C., & Mayrhofer, A. (2007). International Baccalaureate Biology (3rd ed.). Victoria, Australia:
IBID Press. p.293.
E.6.5

Explain how mate selection can lead to exaggerated traits.
In animal species that reproduce sexually, the quality of the mate may be critical to reproductive
success.
Therefore, it is common that animals choose their mates specifically and not at
random

Sexual selection:
is the name Charles Darwin gave to the struggle between individuals of one
sex (normally the males) for the possession of access to individuals of the opposite sex
 (outcome for a ‘loser’ in this struggle is few or no offspring)

The winners in the struggle may depend on the usage of a special feature or structure of
behavior  when the succeeding male in the struggle of sexual selection mates with a female,
the special feature/behavior that allowed it to attract the female will be passed down to their
offspring, and this trend will continue over generations

The long term outcome of this passing of the special trait has been the evolution of exaggerated
traits  this exaggerated trait helps draw attention to a potential mate and increases possibility
of reproductive success
Example:

Peacock
Male peacocks are well known for their
magnificent display of feathers (their tail)

Evidently, the feathers have been demonstrated
to be associated with courtship and mate
selection, ability to attract female peacocks
(called peahens)

It has been found that peahens choose their mate
based on the size and shape of the peacocks

tail
according to theory of natural selection
that states in sexual selection: traits such as the
large/colorful tails of the peacocks evolve
because females prefer the highly decorated tails
as well as taking into account the number of
eyespots on the tail which indicates quality of tail

When females choose males with longer tails,
those males will father more offspring than other
males and the trait will become exaggerated in
the species resulting in an excess growth of the
large-tailed population

Originally, tail size and the number of eyespots
may have had a real advantage, but it may now
just be a sign of the best male

As this exaggerated trait becomes dominant among the species, it could also become extreme
because there will be a point where the tails are too big or too colorful
 Consequently, the
exaggerated trait could attract a new predator and therefore, the trait could potentially be
disadvantageous
Exaggerated Tail (feathers w/ lots of eyes) of a Male Peacock
E.6.6: State that animals show rhythmical variations in activity
What is a rhythmical variation?

Rhythmical variation refers to when an animal has a cyclical pattern in psychological changes or
a repetitive lifestyle.
Rhythmical variation is a way in which the animal adapts to its
environment. The animal can also inherit it from the environment it came from. The
rhythmic pattern is described by the frequency of the activity or the amount of time it takes for
an activity to be done.

There is said to be a “biological clock” which controls rhythms of animals. It is an internal
mechanism by which rhythmical variation occurs in absence of environmental stimuli (eg.
putting a hamster in darkness; it will not become used to spinning in darkness right away/ in
humans:
jet lag )
Rhythmical Patterns with brief examples:
Circadian / Diurnal cycles Activities of animals is based on daily cyclical changes in
environment
Most animals have increased activity during the day but nocturnal animals prefer night / activity
of marine organisms based on tide
Annual cyclesYearly cyclical changes
(eg. male and female red deer are generally sexually active during the fall season. When they
mate, the offspring are born during the spring when the most food is available. Thus, mating at
this time means that there is a better chance of survival for the newborns.
Seasonal cycles  Cycles according to season (Winter, Spring, Summer, Autumn)
(eg. bird migrations)
Lunar cycles  Cycles following the orbit of the moon
Reproductive behavior of marine animals can show lunar rhythms. Protozoa Conchopthirius
lamellidens conjugates most freely after full moon.
Tidal cycles  Cycles following the tidal patterns which correlate with the Lunar Orbit
Lunar cycles are directly related to tides. Many marine animals follow tidal rhythms. A sea
anemone, Actinia equine has a tidal rhythm in its expansion and contraction cycle.
E.6.7 Outline two examples illustrating the adaptive value of rhythmical behavior patterns.
Rhythmical behavior:
rhythmic behavior is inherent to biological systems. Rhythms are closely
associated with all forms of life:

The female ovarian cycle (hormonal rhythm)

The cell division cycle

The pollinating and flowering rhythms’
(1) One example of rhythmical behaviour patterns in biological
organisms is the fiddler crab, also called Uca:
-
The courtship behavior of the crab is linked to the new and full moon,
which acts as a conditioned stimulus.
-
The lunar cycle therefore coordinates the courtship displays to the
best tidal periods.
-
Standing at the front of the burrow the male entices in the female with a display of his enlarged claw.
-
Once in the burrow the entrance is sealed and the pair mate.
-
The adaptive value of the behavior is in linking the display to the best display period between tides.
(2) In Cicadas (Eastern US), more specifically, in Magicicada:
-
6 types of species of this.
-
3 emerge every 13 years and 3 emerge every 17 years.
-
They spend most of their lives underground as “herbivorous nymphs” and
emerge only for a few days to breed. After this, they die.
-
The offspring go back underground to continue the cycle.
-
Cycle lengths: prime numbers. Their cycle of reproduction and
emergence makes it difficult for predators to follow this cycle.
-
Though they only emerge for a few days, they emerge in millions. Predators should be able to take
advantage of this, but since their cycles do not match, they cannot do this.
-
Thus, this adaptive value of rhythmic behaviour in the Magicicada proves to be successful.
Consulted: RavenBiology.
This is a really good video that explains rhythmic behavior in depth:
http://videolectures.net/eccs07_goldbeter_orb/