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Chapters 19 / Evolution: Mechanism and Evidence
I. Introduction
Evolution: genetic change in organisms over time
--populations
microevolution
--species: interbreeding group of individuals that produce fertile offspring
speciation
--macroevolution: evolutionary change above the level of species (genera, orders, etc.);
evolution of major groups of organisms (and major phenotypic
changes)
Concept of evolution is the unifying theme in biology.
II. Early Ideas of Evolution
A. Geological clues
1. rock layers
geological time scale
2. remnants of organisms-- W. Smith*
a. What is a fossil?
b. conditions for fossil formation
c. dating fossils
i. correlation with rock strata (layers)--C. Lyell
ii. radiometric dating
B. How does evolution occur?—Lamarck’s early evolutionary theory: acquired traits
inherited*
III. Describing Evolution: Charles Darwin
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A. Background
1. naturalist
2. voyage of the HMS Beagle
3. observations
a. biogeography
b. fossils
c. similar appearing organisms in similar habitats
convergent evolution: similar traits exhibited in organisms that did not originate
from a common ancestor, but represent similar adaptations to similar
environments.
B. Adaptation and natural selection
Origin of Species by Means of Natural Selection 1859
“decent with modification”
1. adaptation:
divergent evolution: new species or lineages arising from a common ancestor
*adaptive radiation: divergence of new types of organisms (possessing modified
traits) from a single ancestor
2. natural selection
a. premises
--tendency of overproduction of offspring
--variation among offspring
--competition among organisms for limited resources
Some offspring may exhibit forms of traits more favorable for their particular
environment.
*b. sexual selection
--preferential selection of forms of traits by a member of the opposite sex; confers
reproductive advantage
C. Synthetic theory of evolution
--merging Darwin’s ideas with Mendelian genetics:
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Natural selection of certain traits + why variation exists and how traits are inherited
IV. Evolution in Action
Emerging (and remerging) Infectious Diseases
--antibiotic resistant bacteria
V. Evidence Supporting Evolution
A. Fossil record
paleontology: study of fossils and the fossil record to decipher evolutionary origins
and relationships
phylogeny: evolutionary history of a particular lineage
geological time scale
1. conditions for fossil formation
2. dating fossils
--correlation with rock strata (layers)
--radioisotope dating
B. Comparative anatomy of related species
homologous structures vs. analogous structures
divergent evolution vs. convergent evolution
C. Mimicry
--strong resemblance of one species to another species or an inanimate object
D. Patterns of development between related species
(Comparative embryology)
E. Distribution of plants and animals
--biogeography: each species evolved once from a single point of origin
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F. Evidence from molecular biology
1. protein sequences
2. DNA sequences
*Note: review your notes to discern what details we covered on this topic
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