Download NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION

NATURAL SELECTION AND THE
EVIDENCE FOR EVOLUTION
Chapter 15.1
I. CHARLES DARWIN AND NATURAL
SELECTION
• Evolution: a series of adaptations “over time”
• Charles Darwin developed this theory of
evolution
I. CHARLES DARWIN AND NATURAL
SELECTION
• A. Fossils Shape and Ideas About
Evolution
• Fossils form base of evolutionary thoughts
I. CHARLES DARWIN AND NATURAL
SELECTION
• B. Darwin on HMS Beagle
• Took this ship (HMS Beagle) on a 5 year
scientific journey around the world
• Collected fossils at every port along route
• Compared each to determine evolutionary
relationships
• Studies provided the foundation for evolution by
natural selection:
▫ Organisms with most favorable traits survive and
pass those traits on to their offspring.
I. CHARLES DARWIN AND NATURAL
SELECTION
• C. Darwin in the Galapagos
• Galapagos are a group of small islands near the
equator
• He studied organisms there that are unique to
the island, but similar to those elsewhere
• Led Darwin to believe that species can “change
over time”
I. CHARLES DARWIN AND NATURAL
SELECTION
• D. Darwin Continues his Studies
• Darwin observed that the traits of individuals vary in
populations. Variations are then inherited.
• Breeding organisms with specific traits in order to
produce offspring with identical traits is called
artificial selection.
• Darwin hypothesized that there was a force in nature
that worked like artificial selection.
I. CHARLES DARWIN AND NATURAL
SELECTION
• D. Darwin Continues his Studies
• Natural selection is a mechanism for change in
populations.
▫ occurs when organisms with favorable variations
survive, reproduce, and pass their variations to the
next generation.
▫ Organisms without these traits are less likely to
survive
I. CHARLES DARWIN AND NATURAL
SELECTION
• E. Darwin Explains Natural Selection
• In nature, more offspring than can survive are
produced
• In any population, individuals have variations
• Over time, those with favorable variations
survive and pass those traits on to their offspring
• Over time, individuals with variations look
entirely different from their ancestors and make
up a large portion of the population
I. CHARLES DARWIN AND
NATURAL SELECTION
• F. Interpreting Evidence After Darwin
• After much investigation, a majority of scientists
have accepted Darwin’s theory of Evolution by
natural selection
II. ADAPTATIONS: EVIDENCE FOR
EVOLUTION
• Adaptation: any variation that aids an
organisms chance of survival in its environment
• Darwin’s theory explains how some of these
adaptations may occur
II. ADAPTATIONS: EVIDENCE FOR
EVOLUTION
• A. Structural Adaptations Occur Over
Time
• adaptations in species develop over many generations
II. ADAPTATIONS: EVIDENCE FOR
EVOLUTION
• A. Structural Adaptations Occur Over
Time
• Mimicry is a structural adaptation that enables one
species to resemble another species
▫ a harmless species has adaptations that result in a physical
resemblance to a harmful species
▫ Predators that avoid the harmful looking species also avoid
the similar-looking harmless species
Syphrid Fly
II. ADAPTATIONS: EVIDENCE FOR
EVOLUTION
• Camouflage: an adaptation that enables species to
blend with their surroundings.
▫ Because well-camouflaged organisms are not easily found
by predators, they survive to reproduce.
Camouflage
II. ADAPTATIONS: EVIDENCE FOR
EVOLUTION
• B. Physiological Adaptations Can
Develop Rapidly
• Physiological adaptations are changes in an
organism’s metabolic processes
▫ Example is penicillin resistant bacteria
▫ Can also be seen in some species of insects and weeds
that are pests
▫ Some things develop an “immunity”
III. OTHER EVIDENCE FOR
EVOLUTION
• A. Fossils
• Even though fossil record is incomplete, it still
gives scientists a good idea of how organisms
evolved
• For example, the evolution of the camel
Camel Evolution
III. OTHER EVIDENCE FOR
EVOLUTION
• B. Anatomy
• Homologous structures: structures with
common evolutionary origin
▫ same structure, same function, or same in both
cases
Homologous Structures
Crocodile
forelimb
Whale
forelimb
Bird
wing
III. OTHER EVIDENCE FOR
EVOLUTION
• B. Anatomy
• Analogous structures: structures that have
NO COMMON ORIGIN, but are similar in
function
▫ Ex: insect wings and bird wings
III. OTHER EVIDENCE FOR
EVOLUTION
• B. Anatomy
• Vestigial structures: a body structure in a
present-day organism that no longer serves its
original purpose, but was useful to an ancestor
▫ ex: eyes of blind mole rats, forelimbs of an
ostrich, pelvic bone in a baleen whale
III. OTHER EVIDENCE FOR
EVOLUTION
• C. Embryology
• Embryo: the earliest stage of growth and
development of both plants and animals
• There are several similarities between fish,
reptile, bird, and mammal embryos
▫ Both have pharyngeal pouches and a tail
• This leads people to believe that all have a
distant common ancestor
Embryology Similarities
III. OTHER EVIDENCE FOR
EVOLUTION
• D. Biochemistry
• Nearly all organisms share DNA, ATP, and many
enzymes among their biochemical molecules
• Scientists compare a specific amino acid
sequence, “Cytochrome c” that is present in
animals all the way from bacteria to bison (a
mammal)
Comparison of Cytochrome c
Biochemical Similarities of Organisms
Comparison of Organisms
Percent Substitutions
of Amino Acids
in
Cytochrome
c Residues
Two orders of mammals
Birds vs. mammals
Amphibians vs. birds
5 and 10
Fish vs. land vertebrates
Insects vs. vertebrates
18-22
27-34
57
Algae vs. animals
8-12
14-18
III. OTHER EVIDENCE FOR
EVOLUTION
• D. Biochemistry
• If organisms are biochemically similar, then they
have fewer differences in amino acid sequences
• If organisms are biochemically different, then
they have more differences in their amino acid
sequences
DON’T FORGET
• Today scientists combine all of the following to
determine evidence of evolution
▫ Fossils
▫ Anatomy
 Homologous, analogous, vestigial structures
▫ Embryology
▫ Biochemical Similarities
Question 1
• ________ is considered to be the fundamental
concept of biology.
A.
B.
C.
D.
Genetics
The Modern Theory of Evolution
Artificial selection
Structural adaptation
Question 1
• ________ is considered to be the fundamental
concept of biology.
A.
B.
C.
D.
Genetics
The Modern Theory of Evolution
Artificial selection
Structural adaptation
Question 2
• Breeding organisms with specific traits in order
to produce offspring with identical traits is
called _________
A.
B.
C.
D.
Natural selection
Adaptation
Mutation
Artificial selection
Question 2
• Breeding organisms with specific traits in order
to produce offspring with identical traits is
called _________
A.
B.
C.
D.
Natural selection
Adaptation
Mutation
Artificial selection
Question 3
• Mimicry and camouflage are NOT examples of
_________.
A.
B.
C.
D.
Adaptation
Natural selection
Evolution
Artificial selection
Question 3
• Mimicry and camouflage are NOT examples of
_________.
A.
B.
C.
D.
Adaptation
Natural selection
Evolution
Artificial selection