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Lecture

BIOA02H3 Lecture Notes - Eusociality, Endocrine System, Inclusive Fitness


Department
Biological Sciences
Course Code
BIOA02H3
Professor
Mary Olaveson

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Biology Chapter 53
Ethology: The study of animal behaviour from an evolutionary perspective
Proximate Mechanisms: the hormonal, neuronal, and anatomical mechanisms of a behaviour
Ultimate Mechanisms: The selection process that shaped its evolution
Stereotypic Behaviour: An unlearned trait (usually species specific) where individuals of a
species performs exactly the same way
Genes do NOT produce behaviour; rather, the product of genes (i.e. enzymes) affects behaviour by
setting forth a series of genetic environment interaction which allows for the appropriate proximate
mechanism that allow for certain behaviours to occur
Deprivation Experiments: A type of experiment where a young animal is reared so it is deprived of
all the experiments needed to perform a behaviour being studied. If the
animal picks up the behaviour regardless, then it is stereotypic
Even if a behaviour is not expressed under the deprived state, it may still be genetically influenced.
Some behaviours are only expressed under certain conditions, influenced by a releaser
Also, genetic experiments such as selective breeding, interbreeding, and gene knockout experiments
also help determine the influence of the environment on a behaviour
Releaser: An object, event, or condition required to elicit a behaviour
I.e. a squirrel brought up in a deprived environment may be thought as not possessing the knowledge or
experience to find nuts and bury them, however when it is actually given a nut, it may perform the act of
biting it and digging a hole to bury it. The nut acts as a releaser.
Critical point: A specific time frame where learning occurs in an organism’s
development
Imprinting: A type of learning where an organism learns a set of stimuli during a
limited critical period. I.e. the recognition of offspring by their parents
and parents by their offspring
The critical period for imprinting may be determined by a brief developmental or hormonal state. I.e. if a
female goat does not nuzzle and lick her newborn within 10 minutes of birth, she will not recognize it as
her offspring. During this time, the goat has high levels of oxytocin in her
Some behaviours are learned through complex interactions between genetics and the environment.
Without either one, the behaviour will not be develop (i.e. a birds song)
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Other behaviours are influenced by the endocrine system, and are expressed in response to a certain
hormones being released
Habitat: The environment that an organism chooses to live
The cues that many organisms use to select their habitat are dependent on whether or not it is a good
predictor of conditions suitable for future survival and reproduction
However, some organisms use visual cues to determine where to live; i.e. whether or not other
individuals of the same species are present
In extreme cases, very social organisms such as honeybees actually vote for where they should live
Territory: A part of a habitat that an animal or set of animals exclusively use; not allowing
other individuals of the same species or different species from entering
Cost-Benefit Approach: An approach that assumes that an animal has limited amount of energy to
devote to its activities. Animals cannot long perform activities where the total
cost is greater than the sum of its benefits
The components of the ‘costs’ of a particular behaviour are:
1. Energetic Cost: the difference between energy that the animal would have
expended had it rested and the energy expended in performing
the behaviour
2. Risk Cost: the increased chance of being killed performing a task,
compared with resting
3. Opportunity Cost: the sum of the benefits the animal forfeits by not performing all
other tasks during that time interval
Foraging Theory: a theory that states that the primary benefits of foraging are the nutritional
value of food obtained (its energy, vitamins, and minerals). The costs of foraging
are similar to those of territorial defence: energy expended, time lost for other
activities that could improve fitness, and the increased risk of death/injury
The choosing of a mating partner may be based on the inherent qualities of the potential mate, or the
resources it controls (food, nest sites etc) or the combination of both
Males and females differ in the way they chose their sexual partner (males typically fight for females,
and seldom reject any female where it’s the opposite for females)
This is because of the costs of producing sperm and egg. For males, sperm is very cheap and easy to
produce therefore they can increase their reproductive success by mating with numbers of females.
Eggs on the other hand are much larger and more expensive therefore to maximize their reproductive
success they are very picky about their mate
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