WEEK 1 – Jan 8 and 9 2014 Studying animal behavior – questions, foundations and methods Part 2 – Foundations of ethology
Raghav Rajan Bio 335 – Animal Behavior Jan 9th 2014 9th January 2014
Bio 335 - Animal behavior - Week 1 - Lecture 2
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Always a case of cause-effect
Proximate mechanisms
What causes the behavior? How does it change over development? Can be answered but in the lab (not natural settings
BEHAVIOR What are the effects on survival, reproductive success? Can be answered in various ways – sometimes practically difficult How did it evolve? Difficult to answer, but we can compare across livingspecies and guess 9th January 2014
Bio 335 - Animal behavior - Week 1 - Lecture 2
Ultimate mechanisms
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Foundations of ethology ●
Natural selection –
Any trait that provides a reproductive advantage would be favoured
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Individual learning
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Cultural transmission
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Natural selection example - Singing behavior of Hawaiian male crickets
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Produces sound by moving smooth scraper on one wing over the serrated file on the other wing Females do not mate with non-singing males
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Natural selection - Singing behavior of Hawaiian male crickets
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But singing also attracts parasites – fly that lays eggs on singing cricket Ultimately leads to death of cricket
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Natural selection - Singing behavior of Hawaiian male crickets ●
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Flies most prevalent on Kauai island – about 30% crickets parasitized With time, Zuk and colleagues heard fewer singing crickets Number of crickets did not change!! Flatwing males that don't make sound – maybe the position of the file changed Flatwing males hardly ever parasitized – should favor survival But, do they mate?? Bio 335 - Animal behavior - Week 1 - Lecture 2
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Natural selection - Singing behavior of Hawaiian male crickets ●
Zuk and colleagues hypothesized that these crickets may stay near singing males and get opportunities to mate
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How to test it?
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Flatwing males were more attracted to these songs
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Maybe they manage to mate by staying close to singing crickets
Songs of normal male crickets
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Foundations of ethology ●
Natural selection –
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Any trait that provides a reproductive advantage would be favoured
Individual learning –
Ability to learn can change the frequency of behaviors during a lifetime
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Natural selection may work on the ability to learn
Cultural transmission
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Individual learning example – hypothetical case of a female bird mating
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Female bird could keep track of mates that produced highest number of offspring Could then change mating pattern accordingly Occurs in the lifetime of an animal, but natural selection can also select for the ability to learn
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Link between natural selection and learning ●
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9th January 2014
Bio 335 - Animal behavior - Week 1 - Lecture 2
Grasshopper foraging has some learned components It learns to associate various cues with food sources
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Learning to associate cues with various food sources
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Balanced diet (b) and deficient diet (d)
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Odors, colors associated with each
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Either consistent pairing (learning) or random
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Learning cues associated with foraging improved fitness
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Both eventually fed more on balanced diet, but those in learning group were faster Higher growth rate – better fitness
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Foundations of ethology ●
Natural selection –
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Any trait that provides a reproductive advantage would be favoured
Individual learning –
Ability to learn can change the frequency of behaviors during a lifetime
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Natural selection may work on the ability to learn
Cultural transmission –
Animals learn by copying others
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New behaviors can spread through populations quickly
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Can also be transmitted across generations
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Cultural transmission example – foraging in rats
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Rats – scavengers Lots of new foods – which one is good, which one is bad? What is the rat equivalent of zomato?
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Indeed rats can learn food preferences from other rats ●
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Observer rat interacts with demonstrator rat (that has eaten rat chow with cocoa) Observer rat now prefers demonstrators diet
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Cultural transmission goes within and across generations
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Unlike individual learning that lasts only that animal's lifetime
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Foundations of ethology ●
Natural selection –
●
●
Any trait that provides a reproductive advantage would be favoured
Individual learning –
Ability to learn can change the frequency of behaviors during a lifetime
–
Natural selection may work on the ability to learn
Cultural transmission –
Animals learn by copying others
–
New behaviors can spread through populations quickly
–
Can also be transmitted across generations
9th January 2014
Bio 335 - Animal behavior - Week 1 - Lecture 2
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Various approaches to ethology
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Conceptual approach – inclusive fitness of an individual ●
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An individual's total fitness measured by genetic contribution to the next generation Direct – viable offspring it produces Indirect – viable offspring of close genetic relatives
Bio 335 - Animal behavior - Week 1 - Lecture 2
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Theoretical approach – choosing what to eat
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Empirical – experimental or observational studies
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Foundations of ethology ●
Natural selection –
●
●
Any trait that provides a reproductive advantage would be favoured
Individual learning –
Ability to learn can change the frequency of behaviors during a lifetime
–
Natural selection may work on the ability to learn
Cultural transmission –
Animals learn by copying others
–
New behaviors can spread through populations quickly
–
Can also be transmitted across generations
9th January 2014
Bio 335 - Animal behavior - Week 1 - Lecture 2
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Project ●
Pick an animal
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Observe and record in detail the behavior
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Ethograms, behavior transitions, time spent in each behavior, etc. Make hypothesis about one of these behaviors (Tinbergen's four questions) Design experiments Assignments at various stages, end semester report in the form of a journal article – description of behavior, hypothesis, proposed experiments, predictions, discussion
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Description of animal behavior ●
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Ethogram – a pictorial representation or description of all possible behaviors in a particular context Important to observe carefully and record in as unbiased a fashion as possible –
Detailed descriptions
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Descriptions of behavior as is without interpretations
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Break down into simpler individual elements
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Helps to quantify, to compare, etc.
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Serves as a record
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Sample ethogram
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Time-budget analysis ●
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In a given period of time (say 15 min.), what is the proportion of time spent doing each of the behaviors in the ethogram Pie-chart, bar graphs, etc.
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Bio 335 - Animal behavior - Week 1 - Lecture 2
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Sampling strategies ●
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Ad-libidum sampling – record as much info as possible – non-systematic Focal animal sampling – actions of one animal during a predetermined fixed duration (say 1 hour) All occurence sampling – record all occurrences of a particular behavior Instantaneous or scan sampling – look at behaviors of lots of animals at a given time –
You can either record the proportion of behaviors shown by one animal
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Or record the behaviors shown by a large number of animals at a given time and infer above
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Sequence transitions in behavior ●
What behavior follows what behavior and with what probability
