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Chapter 10
Principles of Evolution
Evolution
Process of biological change by Process of biological change by which descendants come to which descendants come to differ from their ancestorsdiffer from their ancestors
A gradual change in species A gradual change in species over generations in over generations in
response to changes in the response to changes in the environmentenvironment
Naturalists who’s thinking set the stage for the development of Charles Darwin’s
theory
Darwin’s theory was a result of many years of study, and required the expertise of
many scientists to further explain observations
he made during his mid twenties
Erasmus Darwin
Charles grandfather, doctor and poet published in 1796
– all living things were descended from a common ancestor
– that complex life rose from simple life.
“A fool you know, is a man who never tried an experiment in his life”
Jean Baptiste Lamarck In 1809 he published
Philosophie Zoologique
A 'tendency to perfection', an innate quality of nature that organisms constantly 'improved' by successive generation
Inheritance of acquired traits, physical changes could be inherited and driven by environmental change
Theory of Inheritance of Acquired Traits
Modifications acquired during one’s lifetime are inherited by the next generation
implies that the organism itself can control the direction of change
Lamarck also believed species never went extinct, although they may change into newer forms
How Geology set the stageCatastrophismCatastrophism
Catastrophic events were
responsible for mass
extinctions
Gradualism
Change is a result of small steps over long periods of
time
Charles Lyell Principles of Geology
Uniformitarianism: processes that alter the Earth are uniform through long periods of time
The processes are still at work today
This theory expanded upon gradualism and eventually replaced catastrophism as the favored geological theory yell
Lyell met with Charles Darwin frequently to discuss Darwin’s theory “On the Origins of Species”
Alfred Wallace (1823-1913)
English Naturalist Studied the Amazon RainforestWrote several letters to Darwin Came about with the same theory at about the same time
Thomas MalthusBritish economist 1766-1834
Food, water, and shelter are natural limits to population growth.
population left unchecked will outstrip man's ability to live on this planet
The Theory of Evolution by means of Natural Selection
Charles Darwin (1809-1882)
English Naturalist
HMS Beagle age 22 ship's naturalist 5 year voyage 1831-1836
Published the book “Origin of Species” in 1859
The Voyage of the HMS Beagle
The Theory of Natural Selection
Variations are based on natural selection
Overproduction leads to competition
Adaptation- certain variations can allow an organism to survive better “Survival of the Fittest”
Natural selection acts on phenotype
“Nothing in biology makes sense, except in the light of
evolution”Theodosius Dobzhansky geneticist
Natural Selection in Action
The Peppered Moth
Evidence of Evolution
I. The fossil record- episodic speciation, mass extinction
II. Geographical distribution of species
III. Embryology- compare embryo development to determine lineage
IV. Anatomical Evidence
I. Homologous Structures-
II. Analogous Structures
III. Vestigial Organ- serves no useful purpose
How a How a fossil fossil formsforms
1
2
3
4
5
Mass extinction 25-70% of species wiped out
Generally followed by a period of adaptive radiation
BiogeographyThe geographical distribution of living things
Plant Biogeogra
phy
Animal Biogeogra
phy
Comparative Embryology
Homologous & Analogous Body structures
Similar in structure but appear different and have
different functionsShared common ancestor
Perform similar function but not
common ancestor
Vestigial Structuresremnant of early ancestorremnant of early ancestor
Comparative DNA analysis