Transcript ENVI 30 Environmental Issues

I.
History of Evolutionary Thought
A.
Before Darwin
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Concept of evolution predates Darwin by >2000 years
(not widely accepted)
Fossils known long before Darwin and recognized as
remains of organisms
Aristotle (384-322 B.C.)
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1.
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2.
Organisms could be arranged on a natural scale of
increasing complexity (scala naturae)
Species fixed and unchanging
Carolus Linnaeus (1707-1778)
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Swedish physician who founded taxonomy
Believed in natural theology (study nature to understand the
Creator)
Developed binomial nomenclature and modern classification
hierarchy
Did not intend system to reflect evolutionary relationships
I.
History of Evolutionary Thought
A.
Before Darwin
3.
James Hutton (1726-1797)
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4.
Gradualism
Jean Baptiste de Lamarck (1744-1829)
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5.
Old earth, adaptation (natural change w/o divine
guidance), evolution
Thomas Malthus (1766-1834)
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6.
Population increase  Competition for survival
Georges Cuvier (1769-1832)
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7.
Paleontology, extinction, catastrophism
Charles Lyell (1797-1875)
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Uniformitarianism
Fig. 22.2
I.
History of Evolutionary Thought
B.
Charles Darwin (1809-1882)
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Went to University of Edinburgh at 16 to study
medicine
Transferred to Cambridge University; changed
major to theology
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Became protégé of botanist
Initial observations for theory of evolution made
on 5-year cruise to prepare navigation charts for
British Navy; naturalist aboard HMS Beagle
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1831-1836
Fig. 22.5
I.
History of Evolutionary Thought
B.
Charles Darwin (1809-1882)
1.
Crucial information for development of theory
a.
Similarities & differences among species in Galapagos
Islands vs. South America
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Suggested divergence from common ancestor
b. Principles of Geology (1830) by Lyell
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Contradicted idea of static, young earth
c. Artificial selection
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Selective breeding in dogs, cattle, wild mustard
Fig. 22.9
I.
History of Evolutionary Thought
B.
Charles Darwin (1809-1882)
1.
Crucial information for development of theory
a.
Similarities & differences among species in Galapagos
Islands vs. South America
•
Suggested divergence from common ancestor
b. Principles of Geology (1830) by Lyell
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Gradualism contradicted idea of static, young
earth
c. Artificial selection
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Selective breeding in dogs, cattle, wild mustard
d. Writings of Malthus on population growth
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Suggested that not all offspring can survive when
resources are limited
I.
History of Evolutionary Thought
B.
Charles Darwin (1809-1882)
2.
Major components of evolutionary theory
a.
Descent with Modification
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Recognized that groups in Linnaeus’ classification
hierarchy could reflect patterns of descent from
common ancestors
b. Natural Selection
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Mechanism by which populations adapted to local
conditions
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Developed from five major observations and three
inferences (according to Ernst Mayr)
I.
History of Evolutionary Thought
B.
Charles Darwin (1809-1882)
3.
Observations
a.
b.
c.
d.
e.
4.
Overproduction – Not all offspring survive to reproduce
Stability – Populations tend to remain stable in size
Limited Resources
Within-Species Variation – Not all individuals identical
Heritability – Traits passed from parent to offspring
Inferences
a.
b.
c.
Competition – Leads to limited survivorship
Differential Fitness – Best adapted individuals most
likely to survive
Gradual Change – Favorable traits accumulate over
generations
II.
Evidence for Evolutionary Theory
A.
Natural Selection
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Has been tested experimentally
Fig. 22.13
II.
Evidence for Evolutionary Theory
A.
Natural Selection
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Has been tested experimentally
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Soapberry bugs
Drug resistance
II.
Evidence for Evolutionary Theory
B.
Homologies
1.
Anatomical
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Homologous features derived from same structure in
ancestor
Homoplastic features arose from same functional need
(convergent evolution)
Some important clues to ancestry come from vestigial
structures
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Ex: Hindlimb bones in whales and some large
snakes
Fig. 22.15
II.
Evidence for Evolutionary Theory
2.
Embryological
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3.
Features in early development often conserved
throughout a taxon
Ex: Gill pouches and tail in mammals, just like fishes,
amphibians, reptiles, birds
Molecular
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Divergent traits based on divergent genes and proteins
Some proteins and parts of proteins diverge more than
others (some regions conserved)
Fig. 22.16