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Biology 441 Lecture 2: 9/10/07. Last time: Course mechanics, What is animal behavior?, Why study animal behavior? This time: History and Review of Evolution (& things I forgot to say) Next time: Proximate and Ultimate causes of behavior. Introduction to Ethology: Historical Perspectives. - PowerPoint PPT Presentation
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Biology 441Lecture 2: 9/10/07
Last time: Course mechanics, What is animal behavior?, Why study animal behavior?
This time: History and Review of Evolution (& things I forgot to say)
Next time: Proximate and Ultimate causes of behavior
Introduction to Ethology: Historical Perspectives When did the study of animal behavior emerge?
Introduction to Ethology: Historical Perspectives When did the study of animal behavior emerge?
As far back as recorded history!!! (cave paintings; petroglyphs)
Animals were sources of FOOD and FEAR
Introduction to Ethology: Historical Perspectives Aristotle (384-322 B.C.)
First written records of mutualism, tool use, and brood parasitism
Introduction to Ethology: Historical Perspectives Three advances
1. New Detailed biological knowledge : studies in inheritance and genetics; Human anatomy: structure of nervous system and brain (Helmhotz 1850)
Introduction to Ethology: Historical Perspectives Three advances
1. New Detailed biological knowledge 2. The Origin of Species 1859
Natural selection Sexual selection
Introduction to Ethology: Historical Perspectives Three advances
1. New Detailed biological knowledge 2. Darwin: The Origin of Species 1859 3. Development of a comparative method
Introduction to Ethology: Historical Perspectives Darwin’s contributions: 3 other books
1. Variation of animals and plants under domestication Argues that artificial selection can act on behavior as
well as morphology
Introduction to Ethology: Historical Perspectives Darwin’s contributions
1. Variation of animals and plants under domestication 2. Expression of the emotions in man and animals
Principle of servicable habits Antithesis
Introduction to Ethology: Historical Perspectives Darwin’s contributions
1. Variation of animals and plants under domestication 2. Expression of the emotions in man and animals 3. The descent of man
Similarity between human and primate expressions Similar states of mind?
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes’Animal Intelligence
“mental continuity”
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes’Animal Intelligence
“mental continuity” ANTHROPOMORPHISM
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes C. Lloyd Morgan
Law of Parsimony
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes C. Lloyd Morgan
Law of Parsimony“in no way may we interpret an action as an outcome
of the exercise of a higher faculty if it can be attributed as the outcome of one that stands on a lower physical scale”
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes Conway Lloyd Morgan James Watson & B.F. Skinner (“Skinner Box”)
Strictly objective view of behavior All behavior can be explained by stimuli/response
mechanisms & reinforcement Ignored any higher mental processes, motivation, hormones, etc.
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes Conway Lloyd Morgan James Watson & B.F. Skinner (“Skinner Box”)
Behaviorism Considered sterile and divorced from reality
Introduction to Ethology: Historical Perspectives The Comparative Method
George Romanes Conway Lloyd Morgan James Watson & B.F. Skinner (“Skinner Box”)
Behaviorism Considered sterile and divorced from reality
“Give me a dozen healthy infants, well-formed, and my own specified World to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select—doctor, lawyer, artist, merchant-chief and yes, even beggar-man and thief…”
Introduction to Ethology: Historical Perspectives Birth of Ethology (early 1900s)
Extensive observation of animals in their natural environments
Introduction to Ethology: Historical Perspectives Birth of Ethology (early 1900s)
Observation of natural behavior: First creation of ETHOGRAMS
Recognition of species-specific patterns Questions as to how these patterns arise; what is the
adaptive significance?
Introduction to Ethology: Historical Perspectives Birth of Ethology
Observation of natural behavior: ETHOGRAMS Recognition of species specific patterns 1940’s Konrad Lorenz & Niko Tinbergen (Fathers of
Ethology)
Introduction to Ethology: Historical Perspectives Lorenz
Pioneered studies of genetically programmed behavior (instinct)
Concept of imprinting
Introduction to Ethology: Historical Perspectives Tinbergen
Field biology Developed Ethology’s 4 areas of inquiry
Introduction to Ethology
Aims and Methods of Ethology: 4 Areas Causation
Introduction to Ethology
Aims and Methods of Ethology: 4 Goals Causation Development
Introduction to Ethology
Aims and Methods of Ethology: 4 Goals Causation Development Function
Introduction to Ethology
Aims and Methods of Ethology: 4 Goals Causation Development Function Evolution
(Tinbergen 1963)
Evolution: the Basics
What is Evolution?
Evolution: the Basics
What is Evolution? any change in allele (gene) frequencies in a population
over time
Evolution: The Basics
What is Evolution? any change in allele (gene) frequencies in a population
over time
What is a population? A localized group of organisms which belong to the same
species
Evolution: The Basics
What is Evolution? any change in allele (gene) frequencies in a population over
time
What is a population? A localized group of organisms which belong to the same
species
What is a species? A group of populations whose individuals have the potential to
interbreed and produce fertile offspring in nature
Evolution: The Basics
What is Evolution? any change in allele (gene) frequencies in a population
over time
What is an allele?
Evolution: The Basics
What is Evolution? any change in allele (gene) frequencies in a population
over time
What is an allele? A variant of a gene or trait
Evolution: The Basics
Examples of variation in traits Eye color (blue, brown, hazel, green) Timing of shell-removal for black-headed gulls
(45, 50, 60 minutes after hatching etc.)
Evolution: The Basics
If frequency of particular variants of traits changes over time = evolution
Evolution: The Basics
Change happens, therefore Evolution is fact I.e., Species change over time
Evolution: The Basics
Change happens, therefore Evolution is fact I.e., Species change over time
Details of how this change occurs is explained by Darwin’s Theory of Natural Selection
Darwin & Natural Selection
Observation 1 All species have great potential fertility
Observation 2 Populations remain stable
Observation 3 Environmental resources are limited
Darwin & Natural Selection
Observation 1 All species have great potential fertility
Observation 2 Populations remain stable
Observation 3 Environmental resources are limited
Inference 1 struggle for existence
Darwin & Natural Selection
Observation 4 Individual variation exists in populations
Observation 5 This variation is heritable
Darwin & Natural Selection
Observation 4 Individual variation exists in populations
Observation 5 This variation is heritable
Inference 2 Survival in the struggle for existence is not random
Inference 3 This leads to gradual change in populations with the
accumulation of favorable characteristics
Example: Black headed gulls
Assume that black-headed gulls have not always removed eggshells
The 1st eggshell remover appeared (perhaps a genetic mutation altered the birds nervous system)
The egg remover had good nest success The “egg removing gene” was passed on Eggshell removing offspring produced more offspring Now all remove eggshells
Natural Selection
= the differential success in reproduction of variants in a population
Natural Selection
Mechanism of adaptive evolution Chance events produce variation Natural selection favors some variants over others
Natural Selection
Evolutionary fitness Def. The relative contribution an individual makes to the
gene pool of the next generation = Success of an organism in producing progeny
Natural Selection
Limitations (I.e., why we don’t see only ‘perfect’ organisms History (constraints) Adaptations are often compromises Not all evolution is adaptive (e.g., inbreeding or chance) Selection can only edit variations that exist Environmental change
Natural Selection: Types
Sexual Selection Sexual dimorphism
Def. Distinction between the secondary sexual characteristics of males and females
Natural Selection: Types
Sexual Selection Sexual dimorphism
E.g., size, plumage, lion manes, antlers, etc.
Natural Selection: Types
Sexual Selection Usually have no adaptive advantage other than to
attract mates Sometimes conflicts with natural selection
Evolution: The Basics
Evolution is fact Species change over time
Darwin’s theory is the only set of principles that adequately explains these facts
Evolution: The Basics
Evolution is fact Species change over time
Darwin’s theory is the only set of principles that adequately explains these facts Source of confusion: theory vs. hypothesis
In order to become a scientific theory, unifying concepts must have predictions that stand up to thorough and continuous testing by experiment and observation
Natural Selection: Summary
1) Natural selection = differential success in reproduction = adaptation to environment
Natural Selection: Summary
1) Natural selection = differential success in reproduction = adaptation to environment
2) Result of interaction between environment and variability in a population
Natural Selection: Summary
1) Natural selection = differential success in reproduction = adaptation to environment
2) result of interaction between environment and variability in a population
3) Variations arise by chance, but natural selection is not a chance phenomenon Specific criteria for reproductive success
Key Points for Behavior
Behavior has a genetic basis and therefore is subject to selection
Unit of selection is the individual he/she who’s behavior results in the highest
number of surviving offspring has the highest evolutionary fitness