Download EVOLUTION

DIVERSITY
Targets
A. Explain what causes species to change over time.
B. Provide evidence that species and environmental
conditions have changed over time.
C. Describe sudden and gradual environmental
changes that would cause extinctions.
Targets
D. Explain the importance of variation in traits
(diversity) of a specie.
E. Describe the causes of variations in species.
F. Explain how the age of fossils can be determined.
Targets
G. Compare relative and absolute dating methods.
H. Define transitional form and index fossil.
I. Explain what can be determined about extinct
species from the fossil record.
I. Evolution
 Living things have changed through
gradual processes over long periods of time.
 Results in diversity
 About 99% of species that have lived
in the past are now extinct.
A. Family Trees
(Phylogenies)
1. Traces patterns of shared ancestors
between families.
2. Root = Ancestors, Branches = Descendants
Forks = Speciation Event
3. Each family has shared and unique ancestors.
B. The Pace of Evolution
1. Gradual : slow, steady change overtime.
 Transitional forms found.
2. Punctuated : short periods of rapid change.
 Transitional forms may not be found.
Gradual
Punctuated
Transitional Forms
Link between ancestor and descendent
3. Gaps : Why a lack of transitional forms?
a. Fossils may not have been preserved
by the environment.
b. Fossils may have been destroyed by
tectonic activity.
II. Cause of Evolution
A. Competing Theories
1. Acquired Characteristics
 Jean-Babtiste Lamarck, 1809 : The idea that
individuals can acquire new traits in response
to environmental changes, then pass those
traits to their offspring. (after)
2. Natural Selection
 Charles Darwin, 1850’s : Populations that have
inherited the most favorable traits will survive
environmental changes and pass those traits to
their offspring. (before)
Lamark
Darwin
B. Principles of Natural Selection
Variations are found among individuals of a species.
(differences)
 Individuals with helpful variations survive and then
reproduce more than others. (survival of the fittest)
 Over time, individuals with helpful variations or
adaptations make up a larger part of a population.
 Allows speciation to occur.
(development of new species)
III. Variation
A. Importance
1. Changes in the environment can affect how
beneficial a trait will be for survival and
reproductive success of a species.
2. Variation increases the chance that some
individuals will have traits necessary to
survive under changed conditions.
3. If species do not adapt to changes or move to
another location, they may become extinct.
Galapagos Finches
Galapagos Finches
amoeba sisters
Galapagos Tortoises
Natural Selection
Pepper Moths
4. Environmental Changes
a. Sudden:
Catastrophic event such as a
meteor or volcanic eruption.
b. Gradual:
Changes in climate, predators
or food sources.
B. Causes of Variation
1. Mutations
 Random changes in the DNA code that
may cause offspring to develop traits
different from the parents.
2. Migration
 Variation is increased
when members of a
group introduce their
genes into another group.
(gene flow)
3. Isolation
 Populations separated by geography will
change in different ways.
 Changes that occur in one population will not
be passed to the other.
 Over time, the separated populations may not
interbreed, creating a new specie.
4. Sexual Reproduction
 Mixing of genes results in different genetic
combinations, which allows offspring to
be different in form.
IV. Evidence for Evolution
A. Fossil Record
 Disappearance of a specie:
Extinction
 Appearance of a specie :
Evolution
1. Relative Dating (determines order)
a. Principle of Superposition:
 Rock layers are deposited in time
sequence, oldest rocks on the bottom,
youngest on top.
b. Principle of Faunal Succession
 Fossils succeed each other vertically, in a
specific, reliable order.
 Fossils found in a rock layer are the same
age as the rock.
c. Index Fossils :
A fossil that lived in a particular geologic age
used to date the rock layer, or other fossils, in
which it is found.
They must be abundant and widespread.
2. Absolute Dating (numerical age)
 Radiometric : compares the amount of
naturally occurring radioactive isotope with
its decay products.
 Ex: Uranium / Lead (710 m to 4.5 b yrs)
Potassium / Argon (1.3 billion yrs)
Carbon 14 / Nitrogen (5,730 yrs)
3. Info from Fossil Record
 Age, size and shape can be determined
 Diet, movement, soft parts, color, sounds,
behaviors may be inferred.
 Predicts transitional forms.
B. DNA : The more similar the DNA, the more closely
related two organisms are.
C. Comparative Anatomy : comparing
skeletons of extinct and living organisms.
1. Homologous: similar structures that may not
have a common function in related species.
2. Analogous: similar structures that serve the
same function in unrelated species.
analogous
homologous
analogous
homologous
analogous
vestigial structures: loss of ancestral function,
but remain in the descendant.
D. Comparative Embryology
V. Paleo Environments
 How do fossils indicate ancient environments?
A. Fossil Record
1. Fossil Type
Temperate
or
Tropical
Terrestrial
or
Marine
2. Growth Rings (dendrochronology)
Trees
Coral
B. Geologic Record
1. Sediment Type
 Different types of rock form in different
environments.
EX: Limestone / Dolomite: warm ocean water.
Shale : mud
Sandstone : continental / freshwater
Coal measures : swampy forests
2. Ice Cores
 Ice contains gas
bubbles, radioactive
substances, dust, ash
and pollen from
previous climates.