Lecture 13 Flashcards
What is behavior?
- a response to a stimulus mediated by the nervous system
What is stimulus?
senses
- external (ex. sight, touch, smell, sound, etc.)
- internal (ex. feeling hunger, fatigue, fear, pain, etc.)
What is the response to stimulus?
- the action of muscles or glands
- fixed (innate) or plastic (changeable)
ex. stimulus is sight: presence of a potential mate. Response is male display behaviour (during breeding season)
What is behavioural ecology?
- the study of behaviour in animals has historically been part of psychology
- behaviour and evolution
- integrates information from genetics, ecology, and other studies to understand the origins of behaviours and how they affect evolutionary fitness
What are the 2 explanations (hypotheses) for probable causes of behaviours?
- Proximate (mechanistic) visible causes : HOW?
- Ultimate causes: WHY? (underlying reasons)
What is the proximate explanation?
- HOW?
- mechanistic explanation
- how is this behaviour triggered?
- how does this behavior happen?
What are 2 visual cues?
- alignment
- cohesion
How do starlings flock & fly together? explain using the visual cues
- alignment - steer towards average heading of neighbours (same direction as others)
- cohesion - move towards average position of neighbours, and avoid overcrowding
What is the ultimate explanation?
- WHY
- evolutionary explanations are often needed to explain why a certain behavior exists
Why do starlings flock?
- flocks may be more efficient at feeding (finding food sources)
- avoiding predators: more eyes to spot predators; an individual in a flock has a bettwe theoretical chance of surviving to breeding age than a solitary individual (increase fitness)
explain why male Australian redback spiders commit suicide by females using proximate and ultimate explanation
proximate cause: male presents his body to jaws of female after mating
ultimate cause: higher fitness achieved for male by prolonged mating (2x) and then feeding the female after sperm transfer completed!
explain innate behavior
- occurs completely the first time it is performed, no learning required
- strong GENETIC component
explain learned behavior
- develops and changes in response to environmental stimuli
- strong EXPERIENTIAL and ENVIRONMENTAL componenet
REVIEW - describing innate behaviours is tricky and controversial
- some psychology researchers describe an “innate fear” of snakes, spiders, bees, in humans. Wild monkeys all exhibit alarm at seeing a snake
BUT
- human babies and captive-raised monkeys who have never seen a snake are not automatically alarmed. What appears to be an innate adaptation for survival, may actually be a learned behavior
What are FAPs?
Fixed Action Patterns
- triggered by a specific stimulus
- always occurs in the same form
- cannot be changed once started
- largely innate (“hard-wired”
Who studied fixed action patters in male sticklebacks in the 1930s?
Niko Tinbergen
explain this observation using proximate and ultimate explanation: breeding male sticklebacks respond aggressively to other male sticklebacks, and red in belly of models
Proximate explanation
- the aggressive response is triggered by the sight of the red belly (fish image without red is ignored)
Ultimate explanation (evolutionary)
- males who respond aggressively to other males are better able to defend their territory from other males. This increases their access to females, allows them to fertilize more eggs, and thus maximizes their reproductive fitness
What is imprinting?
- innate behaviour that is time-limited
- some species have this behaviour after birth that bonds parents and offspring (birds especially). If parents are missing in critical period, other species or even moving objects may become bonded… (genes + environment both important)
behavioural ecologists often study behaviours associated with what lines of questioning?
- obtaining food (optimal foraging behaviour); involves cost-benefit analyses
- oriented movement and navigation
- communication and cooperation (learning)
- mate choice and sexual behaviour (sexual selection)
What are some examples of social & experiential learning and tool use?
- chimpanzee using a “hammer” to crack open betel nuts
- young chimpanzees learning to crack hard nuts with hammerstones
What is a foraging behaviour?
- obtaining food
explain the white pelican group feedings
- group drives fish into shallow water near shore (COOPERATION EXAMPLE)
- group feeding on trapped fish
- individual success!
ex. pack-hunting of large animals by African wild dogs provides more food per dog than individual hunting of smaller animals
explain the foraging alleles in Drosophila melanogaster (two behaviours, proximate cause, ultimate cause)
- fruit-fly larvae exhibit one of two behaviours during feeding
- “ROVERS” move after feeding in a particular location
- “SITTERS” stay in one location to feed
- Proximate cause : experiments show that this feeding behaviour depends on alleles of the foraging (for) gene
- rovers and sitters tend to behave differently when they are foraging because they have different alleles of the ‘for’ gene
- Ultimate cause: the rover allele is dominant and favoured at high population density while the sitter allele reaches high frequency in low-density populations, and these behaviours also continue in adult flies
- offspring of rovers tend to be rovers, and offspring of sitters tend to be sitters
- rover alleles are favoured when population density is high (find new food sources when crowded)
review well!
Do gerbils “weigh” the costs and benefits of foraging?
Hypothesis : Gerbils reconcile the risk of predation and the benefits of extra food availability
Null Hypothesis: Foraging activity is independent of predation and food availability
Experimental Setup:
1. start with 34 gerbils in each 1-hectare desert subplot in the Negev Desert of Israel
- use the density of gerbil tracks in sampling stations as an index of foraging activity in control versus treatment subplots where:
Treatment 1 - No owl flyovers, no extra seeds
Treatment 2 - Owl flyovers, no extra seeds
Treatment 3 - Owl flyovers, extra seeds of varying quantities
Prediction: a certain amount of added seeds will compensate for the decrease in foraging activity due to predation risk
Prediction of Null Hypothesis: gerbil foraging activity will be independent of the presence of owls, extra seeds, or both
Results: blah blah its a graph
Conclusion: gerbils weigh the relative risk of predation and benefits of extra seeds when they forage
