Download Contents Unit 5- Evolution Chapter 15 I. Evolution A. Central theme

Contents
Unit 5- Evolution
Chapter 15
I. Evolution
A. Central theme of modern biology
II. Early Theories
A. LaMarck 1809
1. Species not constant
2. Inheritance of acquired characteristics Use and disuse
III. Influences on Darwin
A. Charles Lyell
1. Processes occurring now have shaped Earth's geological processes over long period
of time.
2. Earth is very old.
B. Thomas Malthus
1. If humans continue to reproduce unchecked not enough living space or food would be
available.
2. Darwin realized it more strongly applied to plants and animals.
IV. Darwins Theory
A. Competition- living space/ food / is limited
B. Variation- not all individuals of a species are alike.
C. Adaptations- characteristics that increase chance for survival.
D. Natural Selection-Individuals with variations that make them better adapted to their
environment reproduce in greater numbers.
E. Overproduction
Most species produce more offspring than are needed to maintain population.
F. Speciation
Over many generations the accumulated changes become so great that net result is a
new species.
V. Evidence of Evolution
A. Fossils
1. trace or remains of an organism that has been preserved by natural processes.
2. Petrification
a. bone replaced by minerals
3. Casts,imprints
a. sand or mud hardens into rock.- Footprints
B. Age of Fossils
1. Relative dating
a. Using sedimentary rock and index fossils to determine age.
2. Absolute dating
a. Using radioactive isotopes to age rock or fossil. Carbon-14, U-238
C. Comparative Anatomy
1. study of structural similarities and differences between organisms.
D. Homologous Structures
1. Similar structure, similar embryological development, different form and function
E. Analogous Structures
1. Similar form different internal structure.
Bird, insect wing.
Chapter 16
I. Genes and Variations
A. Gene pool
1. all genes present in the population.
B. Relative frequency
1. # of times gene occurs in a gene poll compared to the # of times other alleles of the
same gene occur.
2. Example- allele for black fur in mice- 40%
recessive allele for brown fur- 60%
C. Evolution
1. change in relative frequency of alleles in a population.
D. Sources of Genetic Variation
1. Mutations
a. changes in DNA
2. Gene shuffling
a. from sexual reproduction
E. Single Gene and Polygenic traits
1. the # of phenotypes produced for a given trait depends on how many genes control
the trait.
2. Single gene trait
a. controlled by a single gene
ex. - widow’s peak
3. Polygenic trait
a. controlled by two or more genes
height in humans ( bell shaped curve)
F. Natural selection on single gene traits
1. Can lead to changes in allele frequency
2. Example-Peppered moth
-Before industrial revolution in England- light colored
-During industrial revolution in England
- dark colored few light colored
-Now- more light colored
16- Continued
G. Natural Selection on Polygenic Traits
1. Directional selection
a. individuals at end of curve have higher fitness than middle or other end.
b. Example- Darwin's finches
2. Stabilizing selection
a.ind. in the middle of the curve mav higher fitness
b. Example- Birth weight in humans
3. Disruptive Selection
a. ind at lower and upper ends have more fitness.
-population might split into subgroups
H. Genetic Drift
1. Random change in allele frequency.
2. Individuals that carry an allele may leave more descendants than other individuals by
chance.
3. Founder effect
a. allele freq. change due to migration. Ex.- Fruit flies in Hawaii
I. Hardy -Weinbergy Principle
1. allele freq. will remain constant unless one of more factor causes those freq. to
change.
2. Conditions Needed for NO Change
a. Random mating
b. Very large population
c. no movement in or out of population.
d. no mutations
e. no natural selection
J. Isolating Mechanisms
1. Reproductive isolation
species cannot interbred and form fertile offspring.
2. Behavioral isolation
capable of interbreeding but don’t. ex. Eastern and Western meadowlark- different
songs to attract mates.
3. Geographic isolation
a. separated by physical barriers
4. Temporal isolation
a. species reproduce at different times.
ex. - different orchids release seeds on different days
Chapter 17
I. The Fossil Record
A. Fossils and Ancient Life
1. Paleontologists
a. Scientists who study fossils.
2. Fossil Record
a. Information about past life.
b.
Show how organisms change over time.
B. How Fossils Form
1. Dead organisms are buried by layers of sediment, fossil is petrified in rock layer.
C. Interpreting Fossil Evidence
1. Relative dating
a. Age of fossil is determined by comparing its position with fossils in different rock
layers.
b.
c.
Use index fossils - easily recognized, wide geographic range.
2. Radioactive dating
a. Use of half- life to determine age of a sample.
b.
Calculated by amount of remaining isotope.
c. C-14 - 1/2 life = 5730 years
d. P-40- 1/2 life = 1.26 billion years
D. Geologic Time Scale
1. Divided into eras and periods
2.
Now- Cenozoic era and Quaternary period
II. Earth Early History
A. Formation of Earth
1. Formed form cosmic debris from a star that exploded.
2.
4.6 billion years old.
3.
Early atmosphere- hydrogen cyanide, CO2, CO N, H, H20
4.
At about 3.8 million years cool enough for liquid water.
B. First Organic Molecules
1. Miller and Urey- stimulated conditions on Earth.
2.
Produced organic molecules including cytosine and uracil.
C. Puzzle of Life's Origins
1. Formation of microspheres
a. Bubbles formed formed large organic molecules-can be cell-like
2. Evolution of DNA & RNA
a. Not solvedD. Free oxygen
1. Photosynthetic bacteria produced O2 as waste product of photosynthesis.
2.
Started by 2.2 million yrs. ago- took several 100 million years
3.
O2 more efficient energy pathway.
E. Origin of Eukaryotic Cells
1. Endosymbiotic theory
a. Eukaryotic cells arose from living communities formed by prokaryotic organisms.
b.
Mitochondria- look like bacteria - have own DNA
III. Patterns of Evolution
A. Extinction
1. 99% of species alive once are extinct.
2.
Mass Extinctions
a. 439 million -Ordovician-Silurian extinction -60% marine life
b.
364 million-57% marine life
c. 251 million-Perian-Triassic -Worst extinction- 95% of all species
d. 200 million-End Triassic- 52% marine life
e.
65 million- Cretaceous- Tertiary- Dinosaurs 47% marine
B. Adaptive radiation
1. Single species or small group species evolve into diverse forms
C. Convergent Evolution
1. Unrelated organisms that look remarkably similar.
a. flippers and wings
D. Punctuated equilibrium
1. Pattern of evolution where long stable periods are interrupted by brief periods of more
rapid change.
Chapter 18
I. Finding Order in Diversity
A. Biologist use a classification system to name, and group organisms.
B.
Taxonomy
1. Science of classification.
C. Scientific names
1. Binomial nomenclature
a. Each species has a two part scientific name.
(1) Genus
(2)
Species
(3)
Example= Homo sapiens- ( us)
D. Carolus Linnaeus 1707-1778
1. Father of taxonomy
2.
Developed seven level classification system based on physical
characteristcs
a. Kingdom
b.
c. Class
d. Order
e.
f. Genus
g. Species
Phylum
Family
II. Modern Evolutionary Classifaction
A. Evolutionary classification
1. Cladogram
a. Phylogeny
(1) Study of evolutionary relationships.
b. Diagram using evolutionary relationships.
2. Biochemistry
a. DNA and RNA
b.
Genes
B. Dichotomous key
1. Used to classify unfamiliar organisms.
III. Kingdoms
A. Eubacteria
1. Bacteria
B. Archaebacteria
1. Bacteria that live extreme environments. Hotsprings, brine pools, most in areas w/out
oxygen.
C. Protista
1. Unicelluar mostly-most diverse kingdom
D. Fungi
1. Heterotrophs that feed on dead, decaying matter. Mushrooms, yeast
E. Plantae
1. Multicellular photosynthetic autotrophs, nonmotile , cell walls
F. Animalia
1. Multicellular heterotrophs no cell walls.