Today’s Topics
•
Pre-Darwin Understanding of the Natural World
•
Darwin & Wallace
– Natural
Selection
•
Evidence for Evolution
•
Reception for Evolution
Pre-Darwinian Theories: Biblical &
Classical Interpretations
•
Fixity of Species
–
Created by
God; The Grand Design
–
No Change
•
Young Earth
•
Great Chain of Being
–
Aristotle
–
Linear
–
Simple to
Complex
–
Humans
–
Static /
Non-evolutionary
–
“Grand
Design”
Early Science (1500-1700s)
•
Scientific Revolution
– Heliocentric
“Universe”
• Copernicus
• Galileo
•
European Global Exploration
– Changed Perspective
• Diversity
Scientific Method
•
A way of knowing based on:
– Observation
(Empirical Evidence)
– Generalization
– Verification
(Testing)
– Building on
Previous Developments
•
Contrasts with belief:
– Faith
– Doctrine
Scientific Method (cont’d)
•
Data Collection
– Systematic
– Explicit
– Often
Quantitative
•
Hypotheses
•
Theory
– Theory NOT
“fact” or “truth”
– Constantly
evaluated & refined
– Evolution is a
theory, but has stood the test of time and repeated tests and refinements
John Ray (1627-1705)
•
English Minister
•
Species Concept
– Reproductive
Criteria
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Precursor of Taxonomy
•
Creation and Fixity of Species
Carolus Linneaus (1707-1778)
•
Swedish Naturalist
•
Systema Naturae (1735)
– Classification
System of Plants & Animals
– Taxonomy
– Binomial
Nomenclature
– Static
Comte de Buffon (1707-1788)
•
French Naturalist
•
Natural History (1749)
– Change in
Species
– Ancestral Forms
– Environment /
Adaptation
Erasmus Darwin (1731-1802)
•
Grandfather of Charles Darwin
•
Physician & Naturalist
•
Zoonomia
– Evolutionary
Change
Jean Baptiste Lamarck
(1744-1829)
•
Tried to Explain Evolution
•
Interaction with Environment
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Inheritance of Acquired Characteristics
–
Acquire
characters during life
–
Pass on to
offspring
Lamarck’s View of Evolution
Georges Cuvier (1769-1832)
•
Father of Zoology, Paleontology, Comparative
•
Concept of Extinction
•
But…Fixity of Species
•
Catastrophism
– Fossils
– Multiple
Creation Events
Charles Lyell (1797-1875)
•
Scottish Geologist
•
Founder of modern geology
–
Principles of Geology
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Uniformitarianism
•
Dynamic Earth
•
Old Earth
– “Geologic Time”
T.R. Malthus (1766-1834)
•
English Economist & Demographer
•
“Struggle for Existence”
– Exponential
population growth & limited resources
•
An Essay on the Principle of Population
Charles Darwin (1809-1882)
•
Studied medicine & theology
– Edinburgh
University (but dropped out)
– Cambridge (Christ
College)
•
Voyage on HMS Beagle (1831-1836)
Voyage of the HMS Beagle
•
5-year voyage around world (1831-1836)
-biological & environmental
variation
Galapagos Island Fauna
•
Fauna similar to that on mainland (South America)
•
But…
– No land mammals
– Those birds
& reptiles present have more variation within groups
•
Finches & Tortoises
Adaptive Radiation
•
Rapid Expansion and Diversification (Typically Involving
Speciation) of Organisms When Entering New Environments
– Fill Vacant
Niches
– May Have Limited
Competition
•
Finches (Geospiza spp.)
– 13 Species on
Islands
– 1 Mainland
Species
Darwin’s Post-Voyage Years
•
Species not fixed
– Each population
had a representative type but was not a distinct creation
– Island species
showed origin with local modification
•
Fossils as remnants of extinct life forms
•
All living organisms came from a common ancestor
•
Processes of today same as occurred in past
•
These processes take lots of time
Natural Selection
•
First used in 1842
– Borrowed from
“selection” from animal breeding
•
Evidence from animal breeding
•
Influenced by Lyell & Malthus
– “Struggle for
existence”—competition for limited resources
– “Survival of the
fittest”—more offspring born than can survive
Evolution by Natural Selection
•
Populations Increase Faster Than Food Supply
•
Variation & Heritability of Variation
•
Some Variation More Advantageous—Organisms with Advantageous
Variation Favored:
– Survival
– Reproductive
Success
• Able to mate
• More offspring
• Advantageous traits more common in next generation
• Disadvantageous traits often disappear
Alfred Russel Wallace
(1823-1913)
•
Biologist working in SE Asia
•
1855 publication on evolution
•
1858 paper on “natural selection” sent to Darwin
Evolution = Descent
with modification
= Change
through time
Occurs at level of individual but results seen in trait
frequencies within populations (species)
Darwin’s Evidence
Experimental
•
Domesticated Animals
•
Selective Breeding Experiments
Biogeography
•
Natural distribution of plants and animals around world
– Different
environments, different flora & fauna
Paleontology
•
Geological and Paleontological Evidence
– Old age of Earth
– Fossils of
Extinct Animals
•
Fossils of human ancestors almost completely unknown
– Neandertal
fossil first discovered in 1856 (Germany)
Comparative Anatomy
•
Homology
– Similarities
based on descent (e.g., limb bones)
• Common ancestry
•
Analogy
– Similarities in
unrelated organisms based on similar adaptations (e.g., eyes or wings)
•
Vestigial Structures
– Retentions with
no function (e.g., pelvic bones in whales)
Homologous Traits
-Similar structures, often different
functions
Analogous Traits
-Similar
functions, different structures
Vestigial Structures
Embryology
•
Similarities in embryos with differences in adult life
•
Some retention of ancestral characters lost later in development
– e.g., tail in
ape & human embryos
Darwin’s Problems
•
Trait inheritance
– But proposed
that offspring inherited traits from both parents
•
Variation
– Maintenance
– Origin
Publication & Reception
On the Origin of Species (1859)
-“Much
light will be thrown on the origin of man and his history.”
Thomas Henry Huxley
•
Darwin’s “Bulldog”
•
Debate with Wilberforce
•
Helped win scientific support for evolution
– gradual, NOT revolutionary
•
Today, Evolution NOT controversial in scientific community
Darwin: Burial at Westminster Abbey
Current Evidence for Natural Selection
Industrial Melanism
•
Peppered Moths (Biston betularia)
Industrial Melanism
•
Peppered Moths Near Manchester, England
•
Two Variants of Moth
– Light Color
– Dark Color
– Controlled by 1
Gene
•
Change in Frequencies of Moths over Time
– Environmental
Change
– Natural
Selection
•
Experimental Studies Have Confirmed
Natural Selection in Action
•
Daphne Major Island
– Small
Island—Possible to Band All Birds
– ~1 Hour Walk
Around Perimeter
– Isolated
• No Immigration
• No Emigration
– Enough Birds for
Statistical Analyses
Results
•
Beak Size Heritable & Correlated With Food Items
•
Foods Require Different Energy To Break
•
Drought
–
Selective
Agent
–
More Fit
Birds Survive
–
Beak Form
Frequency Changes in Next Generation
–
Change in
Population Through Time (Evolution) by Natural Selection
Implications of Study
•
Long-Term: Documents Change in Population Through Time
–
Helps Bridge
Gap Between Macroevolution and Microevolution
•
Extremely Detailed
–
Rainfall
–
Food
Abundance
–
Food
Mechanics
–
Bird
Measurements
–
Bird Banding
–
DNA (Blood)
More Evidence…
•
Antibiotic-Resistant Strains of Bacteria
– e.g.,
Tuberculosis
Some Current Beliefs on Evolution in the
US
Evolutionary Beliefs in the US
-from 1997 Gallup poll
Percentage of
people who answered “Yes” to question: Did human beings develop from earlier
species of animals?
Great Britain: 77% Israel: 57%
Germany: 73% Russia: 41%
New Zealand: 66%
Poland: 35%
Italy: 65% United States: 35%
Norway: 65%
Philippines: 61%
Ireland: 60%
Teaching of Evolution in Public Schools
in US
•
Scopes Trial
–
John Scopes,
Tennessee High School Teacher
–
Convicted of
Teaching Evolution—Violation of Butler Act of 1925 (in Tennessee)
–
Reached
Tennessee Supreme Court, Which Upheld Ruling
–
Teaching
Evolution in Tennessee Illegal Until 1967
•
Kansas 1999 Decision; Recently Overturned
•
Current Debates: Creation Science / Intelligent Design