Biology 441 Lecture 2: 9/10/07

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