CH 53 POPULATION ECOLOGY
- Behaviour: observable response of organisms to external or internal stimuli.
- Behavioural ecology: study of how behaviour contributes to differential survival and reproduction of organisms.
o Ex. Black-headed gulls pick up broken eggshells of hatched chick and carry away from nest
o White color of empty eggshell attracts attention of predators such as crows that would kill and eat the chicks
or remaining eggs.
- Ethology: study of animal behaviour, addressed questions about both how animals behave (proximal causation) and
why animals behave in particular ways ( ultimate causation)
o Factors that focus on specific genetic and physiological mechanisms of behaviour, i.e. male deer fight with
other males because of change in day length in fall triggers hormonal changes in body proximal causes.
o Factors that focus on adaptive/evolutionary significance of such behaviours, i.e. male deer fight to mate with
females and pass on genes. Ultimate causes.
53.1 Impact of Genetics and Learning on Behaviour
Fixed Action Patterns are Genetically Programmed
- Innate behaviours are those that seem genetically programmed.
- Some behaviour patterns are not in response to environment
o Ex. Female goose notice egg out of nest, she will extend her neck to egg and roll it back into neck improve
fitness since eggs that roll out could get cold and fail to hatch.
- Fixed action pattern (FAP) : a behaviour that once initiated will continue until completed, even if the egg was
removed, goose still rolls nonexistent egg back to nest.
- Sign stimulus: the sign that egg has rolled out stimulus acts on goose CNS
o Any round object elicits egg rolling response.
o Tingbergen’s study of male sticklebacks, males with red belly will attack other males that invade their
territory FAPs and sign stimuli
- Learning: modifications to behaviour based on previous experience.
- Habituation: simplest form of learning, when an organism learns to ignore a repeated stimulus.
- Associative learning: when an association develops between a stimulus and a response
o Classical conditioning: involuntary response comes to be associated positively or negatively with a stimulus
that didn’t originally elicit the response.
o Operant conditioning: an animal’s behaviour is reinforced by a consequence , also called trial-and-error
Cognitive learning involves conscious thought
- Cognitive learning: ability to solve problems with conscious thought and without direct environmental feedback.
o Kohler’s chimpanzee experiment: left chimpanzee in a room with banana hanging from ceiling.
Interaction of Genetics and Learning on Behaviour often imvolves Imprinting
- Many birds learn songs as juveniles, when they hear parents sing.
- Birds genetically programmed to learn the correct song if it is exposed to them.
- Critical period: at this time, many animals develop species specific patterns of behaviour imprinting.
o Ex. Lorenz found young birds imprint on mother during a critical period, usually within a few hours after
hatching, which serves the purpose of mother keeping track of all her offspring.
o Lorenz imprinted greylag geese on himself.
o Newborn shrews imprint on mom’s scent.
53.2 Local Movement and Long-Range Migration Mar/25/11
Local Movement can involve kinesis, Taxis and memory
- Simplest forms of movement are responses to stimuli.
- Kinesis: a movement in response to a stimulus, but one that isn’t directed toward or away from the source of the
o Ex. Woodlice move faster in drier areas and slow down in damp areas to avoid dehydration.
- Taxis: a more directed type of response toward or away from a stimulus
o Cockroaches exhibit negative phototaxis – move away from light.
- Sometimes memory and landmarks may be used to aid in local movements.
o Ex. Tinbergen’s pine cone and wasp experiment.
Migration Involves Long-Range Movement and More complex Spatial Navigation
- Migration: Long range seasonal movement usually movement away from birth area to feed and return to birth area to
- Three mechanisms have been proposed to answer how do migrating animals find their way:
1. Piloting: an animal moves from one familiar landmark to the next
2. Orientation: ability to follow a compass bearing and travel in a straight line
3. Navigation: Ability to adjust or set a compass bearing.
- Starling experiment: juvenile biods continued