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Evolution
and
Darwin
Evolution
 The processes that have transformed life on earth
from it’s earliest forms to the vast diversity
that characterizes it today.
 A change in the genes!!!!!!!!
Old Theories of Evolution
 Jean Baptiste Lamarck (early 1800’s)
proposed:
“The inheritance of acquired
characteristics”
 He proposed that by using or not using its body
parts, an individual tends to develop certain
characteristics, which it passes on to its
offspring.
“The Inheritance of Acquired
Characteristics”
 Example:
A giraffe acquired its long neck because its
ancestors needed to stretch higher and higher into
the trees to reach leaves, and those animals with
longer necks were more likely to reach food and
survive to reproduce. Organisms with shorter
necks couldn’t reach enough food to survive to the
age of reproduction.
Charles Darwin
 Influenced by Charles Lyell who published
“Principles of Geology”.
 This publication led Darwin to realize that natural
forces gradually change Earth’s surface and that
the forces of the past are still operating in modern
times.
Natural Selection
 Individuals with favorable traits are more
likely to leave more offspring better suited for
their environment.
 Example:
English peppered moth (Biston
betularia)
- light and dark phases
Artificial Selection
 The selective breeding of domesticated plants
and animals by man.
 Question:
What’s the ancestor of the domesticated dog?
 Answer: WOLF
Evidence of Evolution
1.
Biogeography:
Geographical distribution of species.
2. Fossil Record:
Fossils and the order in which they
appear in layers of sedimentary rock
(strongest evidence).
Evidence of Evolution
3. Homologous structures:
Structures that are similar because
of common ancestry (comparative
anatomy)
Evidence for Evolution
 4. Vestigial Structures

Organs or structures which were
once useful but no longer provide
any benefit. They do not, however,
have any selective pressure against
them so they remain in the species.
Evidence of Evolution
5. Comparative embryology:
Study of structures that appear during
embryonic development.
6. Molecular biology:
DNA and proteins (amino acids)
Evidence for Evolution
 Evidence comes from every single subcategory of
biology
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Ecology
Cell Biology
Anatomy
Genetics
Biochemistry
Population
 A localized group of individuals belonging to the
same species.
Gene Pool
 The total collection of genes in a population at
any one time.
Species
 A group of populations whose individuals have
the potential to interbreed and produce viable
offspring.
Mechanisms of Evolution
1. Mutation:
Change in an organism’s DNA that
creates a new allele.
2. Non-random mating:
The selection of mates other than
by chance.
3. Natural selection:
Differential reproduction.
Speciation
 The evolution of new species.
 From Turtles to Teenage Mutant Ninja Turtles
Interpretations of Speciation
 Two competing theories:
1.
Gradualist Model:
Slow changes in species overtime.
2. Punctuated Equilibrium:
Evolution occurs in spurts of relatively
rapid change followed by periods of stagnation.
++ Adaptive Radiation
The swift evolution of a single lineage such
as the case of Darwin’s finches
Fossil Records
 Stratification
 Radiometric
dating
(Isotopes)
are used to
date rock
around
fossils
CoEvolution
 The evolution of two or more species counter to one
another