Concept 14.1 Darwin Developed a Theory of Evolution
I. Idea’s From Darwin’s Time
A. Evolution is all of the changes that have transformed life
over time
B. In the mid 1700’s Charles Buffon suggested that the
Earth is older than 10,000 years old
C. In the early 1800’s Jean Baptiste Lamarck developed the
idea of Inheritance of Acquired Characteristics
II. The Voyage of the Beagle
A. In 1831 The HMS Beagle left England for a five year
voyage around the world
B. Darwin studied the geology, plants, and animals he
encountered
III. Darwin’s Observations
A. Darwin maintained extensive journals of his
observations, studies and thoughts
B. Darwin noticed the animals and plants he observed were
uniquely South American
C. Darwin was especially intrigued by the Galapagos
Islands because of their diversity
IV. Ideas from Geology
A. Darwin read books from Charles Lyell that proposed
Earth’s features today could be explained by geological
processes
B. From this Darwin made two conclusions
1. The Earth must be very old
2. Slow and gradual processes occurring over vast
amounts of time could cause tremendous change
V. Darwin Publishes His Theory
A. Over many years after his return, Darwin developed his
theory based on observations, inferences and ideas
B. In 1844 Darwin wrote a 200 page essay that outlined his
idea
C. In 1856 Darwin released his findings to the public in the
book The Origin of Species
VI. Darwin’s Two Main Points
A. Darwin’s first point was that the species of organisms
living on Earth today descended from ancestral species,
Descent with Modification
B. Darwin’s second main point was that Natural Selection
is the mechanism for evolution
Concept 14.2 Evolution has left much evidence
I. The Fossil Record
A. Preserved remains or markings left by organisms that
lived in the past are called fossils
B. The positions of fossils in the rock strata can reveal
relative age
C. The fossil record is this chronological collection of
life’s remains in the rock layers
II. Geographic Distribution
A. The differences and similarities between organisms and
different parts of the world shows how species today
evolved from ancestral forms
B. Geographic distribution gives clues as to how modern
species evolved
III. Similarities in Structure
A. Similar structures in species sharing a common ancestor
are called homologous structures
B. Vestigial structures are remnants of structures that may
have had important functions in an ancestral species, but
have no clear function today
IV. Similarities in Development
A. Embryos of closely related organisms often have similar
stages in development
B. Comparing the development of organisms supports
other evidence of homologous structures
V. Molecular Biology
A. The closer two organisms DNA sequence match, the
closer the relationship
B. DNA and protein analysis are new tools for testing
hypothesis about evolution
C. There is molecular evidence that there are common
genetic codes shared by all species
Concept 14.3 Darwin proposed natural selection as the
mechanism of evolution
I. Darwin’s Theory of Natural Selection
A. A population is a group of individuals of the same
species in the same area at the same time
B. Populations in different areas become more and more
different, leading to new species
II. Observations Lead to A Question
A. There are 13 species of finches unique to the Galápagos
Islands
B. They most closely resemble one finch species living on
the South American mainland
III. More Observations Lead to an Idea
A. Darwin recognized that all species tend to produce
excessive numbers of offspring
B. Darwin also recognized there was variation among the
individuals of a population
IV. Artificial Selection
A. Artificial selection is the selective breeding of
domesticated plants and animals to produce offspring
with traits that humans value
B. You see this change in Dog’s over the last 500 years
V. Pesticides-Natural Selection in Action
A. When a new pesticide is sprayed it will kill about 99%
of the insects targeted
B. As time goes on, more insects are resistant to the
pesticide
C. This illustrates two key points about natural selection
1. natural selection is a “screening” of the traits
available
2. natural selection favors those characteristics in a
varying population that fit the specific current, local
environment
Concept 14.4 Microevolution is a change in a population’s
gene pool
I. Populations and Their Gene Pools
A. A population is the smallest level at which evolution can
occur
B. The gene pool consists of all the alleles in all the
individuals in a population
II. Changes in Gene Pools
A. Natural selection is not random
B. Microevolution is a change in the frequencies of alleles
from generation to generation
C. The Hardy-Weinberg Equilibrium is when a
populations gene frequencies are not changing, i.e. not
evolving
III. Genetic Drift
A. A change in the gene pool due to chance is called
genetic drift
B. The smaller the population the greater the impact
C. The Bottleneck Effect is when a disaster reduces the
size of a gene pool
D. The Founder Effect is when a few individuals colonize
a new habitat
IV. Gene Flow and Mutation
A. The exchange of genes with another population is called
gene flow
B. A mutation is a change in an organism’s DNA
V. Natural Selection and Darwinian Fitness
A. Natural Selection is a blend of chance and sorting
B. Darwinian Fitness is the contribution of one individual
to the gene pool compared to others
VII. A Return to the Galapagos
A. Peter and Rosemary Grant have studied finches on
Daphne Major in the Galapagos
B. Their data has provided clear evidence of natural
selection
Concept 14.5 Evolutionary Biology is important in health
science
I. Natural Selection and Sickle Cell Disease
A. Sickle Cell disease is a recessive disorder which affects
the shape of red blood cells at a ate of 1 out of 25 people
in some African populations
B. Individuals with one copy of the allele are resistant to
developing malaria
C. Natural Selection has selected for those individuals
which are resistant even with the negative affects of the
sickle cell allele
II. Evolution of Antibiotic Resistance in Bacteria
A. Antibiotics kill or slow the growth of bacteria
B. An antibiotic will kill most of the bacteria in a
population but leave those which are resistant behind
soon a greater percentage of the bacteria is resistant to
the antibiotic
C. In New York City, there are strains of the bacteria
which causes Tuberculosis which are resistant to all
three antibiotics used to treat the disease
D. The overuse of antibiotics is the speeding up the
evolution of these strains