Exam I Flashcards
Ethology
the scientific study of animal behavior, especially in the natural context
Tibergen
father of modern ethology
Tibergen’s four questions
approach the study of behavior by asking four questions
- Function - how does the animal’s behavior impact its chances of survival and reproduction
- Causation - what are the stimuli that elicit the behavior and how have the physiological models been modified by experience
- Development - how does the behavior change with age and what are the critical periods?
- Evolutionary History - how does the behavior compare with similar behaviors in related species? how might this behavior have arisen through evolution
John Baptiste Lamark
studied fossils, plants, invertebrates
concluded: transmutation of species (species change over time)
Principles:
( 1 ) Use and disuse (used organs grow stronger, disused ones grow weaker)
( 2 ) inheritance of acquired traits (offspring display traits acquired by parents during lifetime)
Charles Darwin
father of modern biology
Theory of Natural Selection
first described a biological mechanism to explain speciation and the adaption of traits
first to use a comparative phylogenetic method to study behavior
Alfred Wallace - similar ideas
Gregor Mendel
physical traits passed from parent to offspring through genes
Thomas Hunt Morgan
studied flies, found that genes were located on chromosomes
von Frisch
FOCUS: COOPERATIVE BEHAVIOR AND GROUP LIVING
honey bees dance to communicate foraging site distance/direction
Tinbergen
BEHAVIOR IN THE NATURAL WORLD
instinct and learning
sign stimuli: stimulus releases action pattern; input activates a motor program
ex: sticklebacks attack anything red during mating season (color red released attack response)
ex: red herring
Lorenz
INSTINCTIVE BEHAVIOR AND FIXED SEQUENCES
instinctive behavior, fixed sequences
imprinting and critical periods
Lorenz found that geese follow the first moving object they see, during a 12-17 hour critical period after hatching.
imprinting: suggests that attachment is innate and programmed genetically
critical period: within 32 hours, it’s unlikely any attachment will ever develop
in order to understand the mechanisms of animal behavior, it was necessary to observe their full range of behaviors in their natural context
Herring gull
red spot on parent’s bill –> chick hatches –> parents feed on fish –> chick pecks red spot –> parent regurgitates food
Stickleback fish
attack anything red during mating season (color red released attack response)
used when other male sticklebacks that were competing for nesting territory
many false alarms but also relatively few failures to drive off competing male sticklebacks
Stickleback fish
sign stimulus: red
attack anything red during mating season (color red released attack response)
used when other male sticklebacks that were competing for nesting territory
many false alarms but also relatively few failures to drive off competing male sticklebacks
Tinbergin’s 4 questions, red herring
chick pecks on red bill
- Function
allows chick to get fed –> chick can survive and grow, eventually produce its own young - Causation
eyes detect yellow bill with red spot –> visual system perceives signal, motor system sends commands to muscles –> muscles move chick to peck red spot
WHAT ASPECTS TRIGGER RESPONSE? beak shape, spot orientation, color, etc.
head shape, size and color do not matter
cues: (1) color of spot, (2) contrast between spot and bill
- Development
chick performs behavior shortly after hatching, does it before seeing it –> innate - Evolutionary History
laughing gull: chick opens bill and closes it around parent, parent regurgitates to baby
shared trait suggest behavior was present in a common ancestor but red spot evolved after species diverged
Additional lesson from birds
Chick changes behavior after experiencing parent’s response, Behavior can be modified by experience
Example of a behavior resulting from the combination of an instinct to stimulate parent’s bill and learning how to elicit the feeding
sign stimulus
sensory cue that triggers the behavior
(red spot on bill)
ex: Red herring
Sign stimulus for chick = red spot on bright billSign stimulus for parent gull = chick’s pecking on bill
social releaser
sign stimulus that is emitted and received by the members of the same species
super-normal stimulus
an exaggerated sign stimulus
(GIANT red spot on bright bill)
ex: Oystercatchers were willing to roll huge eggs into their nests to incubate
ex:
Black oystercatchers
respond more strongly to super-normal stimuli
Oystercatchers were willing to roll huge eggs into their nests to incubate
Cuckoo Chick
Cuckoo chick and reed warbler
Parasitic cuckoo chick is preferentially fed by host parent because it is larger, begs more and more loudly for food that the host species chicks
Fixed action pattern (FAP)
(FAP) a stereotyped motor response that may be initiated by an environmental stimulus
Chick’s FAP = pecking parent’s bill
Parent’s FAP = regurgitating fish
Sign stimulus –> FAP
Sign stimulus: red spot on bill
FAP: peck
Sign stimulus: peck
FAP: regurgitate fish
Greylag goose
if an egg becomes displaced from the nest, the greylag rolls it back to the nest with its beak
sight of missing egg = sign stimulus
elicits FAP: egg retrieval
Greylag goose
DEMONSTRATES FIXED ACTION PATTERN
if an egg becomes displaced from the nest, the greylag rolls it back to the nest with its beak
sight of missing egg = sign stimulus
elicits FAP: egg retrieval
If the egg is removed from the goose during the performance of egg-rolling, the bird often continues with the behavior, pulling its head back as if an imaginary egg is still being maneuvered by the underside of its beak.[4] The greylag will also attempt to retrieve other egg-shaped objects, such as a golf ball, door knob, or even a model egg too large to have possibly been laid by the goose itself
Chain of reactions
sequences of sign stimuli and FAPs between individuals
ex: mating rituals
ex: stickleback fish
male sees female (ss)
performs zig-zag dance (fap)
female watches male dance (ss)
female displays swollen belly (fap)
male sees swollen belly (ss)
male leads female to nest and prods her into lay egging station (fap) –> female lays eggs
Homology
the evolution of traits that differ but still have similar basic structure due to common ancestral origin
ex: vertebrate limb
Analogy
evolution of similar traits due to similar environmental pressures rather than common ancestor
ex: flying mammals – sugar gliders and flying squirrels
(Natural selection independently adapted both lineages for similar lifestyles: leaping from treetops (hence, the gliding “wings”) and foraging at night (hence, the big eyes)
ex: eye organization (vertebrate and cephaloid)
Scientific Method
- Observe and describe (qualitative stage, what and why)
- Hypothesis (forming an educated guess)
- Prediction (IF…THEN)
- Test Experiment (quantitative stage)
- Drawing conclusions
Scientific Method (A/B)
- OBSERVE Variables A and B are changing
- HYPOTHESIZE Changes in variable A are resulting in changes in variable B
- PREDICT If A increases, then B will increase
- TEST Measure B, increase A, measure B again
- Drawing conclusions
Independent, Dependent Variables
Independent: what you manipulate
Dependent variable: change caused, dependent on independent variable
If I add fertilizer to plant W and none to V, then W will grow faster.
fertilizer: independent variable
growth rate: dependent variable
Null hypothesis
no effect of manipulation
Drawing conclusions based on
magnitude of difference
variability of values
sample size
p-value
Statistical tests of differences between groups give a P-value
P value: likelihood that the observed difference is due to chance
convention = P<0.05
After conclusions drawn
Repeat and continue getting same results
Repeated by different scientists
Establish a consensus that is widely accepted
Theory
a scheme that offers a broad, fundamental explanation of many observations
based on all tested hypotheses
deals with HOW or WHY something happened, not just an idea
Law
empirical statement that summarizes known relationships
states THAT something happened
Francis Bacon
inductive reasoning
- Begin with observations of nature
- Goal is to find true statements about how nature works
- If nature conflicts with the idea, then the idea must be changed or abandoned
Science is a process
theories are based on consensus built among scientists
continuous refinement of understanding rather than definitive proof
don’t assume absolute knowledge, there will always be uncertainty
2 types of experiments
- Planned experiment
- IV manipulated by scientist, DV is measured - Natural experiment
- IV occurs naturally, DV measured
Tephritid experiment
fly mimicking spider
Wing markings and wave display likely mimic jumping spider displays and reduce predation by jumping spiders
Finches (natural)
drought
- Drought resulted in many large, hard seeds, few small soft seeds
- Smaller beaks cannot crack large seeds
- Birds with deeper beaks more likely to survive and reproduce
- Deeper beaks become more common in the populatio
Effect on beak depth in offspring of surviving medium ground finch
Mean beak size eventually returned to original
–> Natural selection favors beak characteristics that allow exploitation of available food type
Kroodsma paper
psuedoreplication
using inferential statistics to test treatment effects with data from experiments where treatments are not replicated or replicates are not statistically independent
If we test the difference in birds’ responses to song A and song B, can we generalize the results to all songs from category A and category B?
Evidence for natural selection
- Domesticated animals change through natural selection
- species change over time, many descendants from single ancestor are possible, selection leads to evolution
- Existence of fossils
- show organisms similar but not same as previous species
- Species change through time
- extinction
- law of succession: fossil species in a given area are replaced by a similar living species
- transitional forms: some fossils show intermediate characteristics between living taxa
- vestigial structures: - Molecular homology
- closely related animals contain similar DNA sequences
- By analyzing the protein structure of complex molecules, relatedness of animals can be estimated
Similarities for natural/artificial selection
Differences for it
variation in populations
some of the variation is heritable
different variants produce different numbers of offspring
difference: agents of selection