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Chapter 6: Evolution – Evidence of Change
I.
Fossil and Evolution
A. What are fossils?
1. What are fossils naturally preserved remains, imprints, or traces of organisms that
lived long ago
a. Examples of fossils include bones, shells, and footprints
2. A paleontologist is a scientist that study fossils
B. When do fossils form?
1. The process of decomposition is part of an organism’s life cycle
a. Decomposition breaks thing down into substances that can be used by other
organisms
b. Organisms that consume and help break down dead organisms are known as
decomposers
c. Scavengers eat dead organisms
2. To become a fossil, dead organism must be well protected from decomposers,
scavengers, and environmental factors
a. Organisms with hard structures such as teeth, bones, and shells are more likely
to become fossils
C. How do fossils form?
1. Fossils only form under certain conditions
2. In the permineralization process, minerals are deposited in the empty spaces of
dead organism
a. Permineralization forms, strong rocklike fossils
b. Most bones become fossilized through permineralization
c. The details of the organism’s hard structure are often preserved
d.
Petrified wood refers to trees that are fossilized by permineralization
3. In the replacement process, the hard parts of an organism are dissolved and replaced
with minerals.
a. The original microscopic details of the organism are partially or totally
destroyed
b. Only the shape of the original organism remains
4. Carbonization occurs when a dead organism is quickly buried under conditions without
oxygen
a. A thin film of carbon that is left behind when hydrogen, oxygen, and nitrogen
leave a dead organism’s remains
b. The carbon film preserves an image or shape of the organism on a rock
c. Many plant fossils are preserved as carbon films
d. Soft animal materials such as skin, fur, and feathers can be preserved as carbon
films
5. The preservation of an impression or indentation of an organism is a mold or a cast
a. Mold and cast fossils contain no remaining parts of the original organism
b. A cast is formed when a mold fills with sediment that hardens into rock
c. Cast are formed entirely from material other then the original organism
6. In an original material fossil, none of the hard or soft structures of the organism
have been altered or replaced
a. The organism is preserved in its original form
D. What do fossils tell us?
1. Much of the evidence for evolution comes from fossils
2. Fossils provide a record or the different organism that lived in the past
3. Older fossils are found in deeper sedimentary rock layers
4. The fossil record is all of the known fossils, their placement in the rocks, and their
position in time
a. The fossil record supports the evolution of plants and animals
b. Te fossil record has gaps in it
c. Most of the species that ever lived on Earth are extinct
5. Fossil evidence can sometimes can sometimes be used to determine if an organism
lived alone or in groups, the kind of food it ate, and the type of environment that it
lived in
II.
Biological Evidence
A. Comparative Anatomy
1. The study of the similarities and differences in the structures of organisms is known
as comparative anatomy
2. In 1976, scientist found fossils of four-winged true flies that confirmed an earlier
prediction that true flies and scorpion flies have a common ancestor
3. Evidence from the study and comparison of the structures of living n organisms with
those fossils support the pattern of evolution
B. Structures in Organisms
1. Parts of an organism that are similar in origin and structure of living organisms with
those fossils supports the pattern of evolution
a. Homologous structures are the result of evolution two or more species share a
common ancestor
b. Homologous structures may indicate how closely
2. Analogous structures appear similar, but have different ancestral origins
a. Examples of an analogous structures include the wings of birds and insects
b. Analogous structures result when similar environmental conditions produce
similar natural selection outcomes over time on remotely related organisms
3. Vestigial structures are structures that have no function in their present-day form
a. Scientist hypothesized that the vestigial structures once functioned in an
ancestor
C. Embryology
1. Embryology is the science of the development of embryos from fertilization to both
a. Similar patterns of embryo development provide clues to the evolutionary
relationships among organisms
b. Embryos of different vertebrates have similar early developmental stages
c. The pharyngeal pouches of vertebrates develop into facial and neck structures
d. The similarities of species are best explained by common ancestors and by
evolution through natural selections
D. Molecular Biology
1. Molecular data supports the theory of evolution through natural selection
2.
Differences in the cytochrome c molecule of different organisms are unlikely to
have developed independently from different ancestral lines
III.
Evolution and Plate
A. Continental Drift
1. Evolution - Evidence of Change are evidence that changes to the Earth’s lithospheric
plates are still occurring
2. As lithospheric plates move, they create environmental change for the organisms
that live on and near them
3. Environmental changes caused by moving plates can lead to the development of and
extinction of species
B. Geographic Isolation
1. Geographical isolation occurs when populations of species are divided or separated
by a physical barrier
a. Geographic isolation can occur when lithospheric plate collide and form mountains
b. Rivers and large bodies of water can also cause geographic isolation of species
c. Once separated by geographic isolation, species may follow different evolutionary
paths if they are in different environments over time
2. Darwin’s observations in Galapagos and Ecuador led to the idea of evolution by
natural selection
C. Convergent Evolution
1. When species evolve independently under similar conditions and develop structural
and functional similarities, the process is known as convergent evolution
a. Convergent evolution results in very distantly related species that appear similar
b. Geographic isolation leads to closely related species that appear differnt
IV.
Classifying Organisms
A. Historical Classification Systems
1. Aristotle, a Greek philosopher, was one of the first people to put organism into
categories
2. In the mid-eighteen century, Swedish botanist Carolus Linnaeus developed a
classification system that grouped organism based on similar physical structures
a. A species includes organisms that have the greatest number of traits in common
and that can breed to produce fertile offspring
b. Only species are subject to natural selection and evolve
B. Naming and Grouping Species
1. Linnaeus developed a system for naming species that is still used today
2. Organisms are classified into level
3. Systematics, the modern study of classification, uses DNA and molecular biology to
identify related organisms
a. The more shared DNA sequences two species have, the more recent an ancestor
they are likely to share
b. A haplotype is the sequence of a sample of 1,000 base pairs of DNA
c. DNA hybridization measures the differences in overall DNA between two
organism
d. Prompted by discoveries made in molecular biology, a new level, the domain, is now
the highest level, positioned above kingdom