Transcript Document

15.1 The diversity of life is based
on the origin of new species
I. What is a Species?
A. Biologist define a species as a
population whose members have
the ability to breed with one
another in nature and produce
fertile offspring.
B. This is referred to as the
Biological Species Concept
II. From Microevolution to
Macroevolution
A. Earlier we saw microevolution
refers to a change in the allele
frequency in a population.
• B. Macroevolution is a dramatic
change
 New species evolving (speciation)
 Extinction of species
 New features of living things
• C. Speciation leads to an increase in
biologic diversity
III. Reproductive barriers
between species
A. Reproductive isolation is a
condition that keeps two species from
interbreeding. Reproductive isolation
usually involves two or more of the
following, but just one is sufficient for
isolation to happen
 Timing- breeding seasons occur at
different times
Reproductive barriers
• Behavior- different mating behaviors
prevent successful mating
• Habitat- species are adapted to specific
habitats in the same area and don’t
interact
• Structure- reproductive structures are
incompatible
• Sterility- mating may occur but
offspring are sterile due genetic
differences
IV. Geographic isolation and
Speciation
A. When one species becomes
physically separated into two
populations, the separation may
lead to two distinct species through
microevolution. This is called
Geographic isolation.
Geographic isolation
B. Species can become geographically
isolated from each other in two ways
1. Geography of the Earth may change
and separate a species
2. The species may be dispersed or
moved to different point on the globe
by other methods (stowaways on ships
or planes)
Geographic
Isolation
Population
Evolution
V. Adaptive Radiation
A. When multiple species arise from
one common ancestor and spread-out
to and adapt to different habitats this is
known as Adaptive Radiation.
B. The numerous types of finches in the
Galapagos Islands are an example of
adaptive radiation.
Adaptive radiation
Adaptive radiation
VI. Tempo or Speed of
Speciation
When species diverge in spurts of
relatively rapid change, then these
new species may remain
unchanged for an extremely long
period in the fossil record this is
known as Punctuated
Equilibrium.
Adaptation Models
15.2 Evolution is usually a
remodeling process
I. Refinement of Existing
Adaptations
A. Complex structures may have
evolved from a similar structure
having the same basic function
B. An example of this would be the
eye which has many interacting
parts
Complexity of eye
II. Adaptation of Existing
Structures to New Functions
A. There are thousands of instances
where existing materials or structures
evolved into new adaptations
B. Chitin originated to help marine
animals from predators, now it is found
in land animals and it is used to fight
dehydration
C. The flippers of penguins are another
example of using old structures for
new functions
III. Evolution and Development
A. Embryology is the study of the
processes of multicellular organisms as
they develop from fertilized eggs to
fully formed organisms
B. Genes that control the development of
an organism are of particular
importance
C. Sometimes the timing or rate of
development plays a role in evolution
Remodeling Process
• Ground and Tree Dwelling
15.3 The fossil record provides
evidence of life’s history
I. How Fossils Form
A. Soft body parts usually decay
quickly, and hard parts like bone, teeth
and shells may become fossils
B. Fossils aren’t always bone, they can
be footprints, burrows, impressions or
even dung
Fossils
II. The Fossil Record and
Geologic Time Scale
A. The Geologic Time Scale organizes
Earth’s History into four distinct ages
known as the Precambrian, Paleozoic,
Mesozoic and Cenozoic Eras
B. Eras are divided into periods and the
periods are divided into epochs
C. New eras are recognized by a major
change in the life forms of that time
Geologic
Time Scale
Geologic Eras
4.6 bya- Precambrian (cells appear &
simple animals)
540 mya- Paloezoic (complex animals &
plants)
245 mya- Mesozoic (dinosaurs &
mammals)
65 mya- Cenozoic (mammals & humans)
III. Dating Fossils
A. Radiometric dating measures
certain radioactive isotopes to
determine the ages of rocks and fossils
B. Half-Life is the number of years it
takes for 50% of the original sample to
decay [y=a(1-r)t ]
C. The half-life is unaffected by
temperature, pressure and other
environmental conditions
Radioactive Isotopes
• Carbon 14 -> carbon 12 (living bone, plants)
• Isotope (more neutrons) -> normal
• Uranium 238 --> Lead 206 (volcanic
rock)
• 100% of isotope = present time
• Less isotope -> older the material
Radioactive Isotopes and Age
Half-Life
IV. Continental Drift and
Macroevolution
A. Landmasses on different plates
change position relative to one another
known as continental drift
B. There are two major events of
continental drift that had a major
impact on the history of life
1. 250 million years ago all the plates moved together
forming Pangea
2. 180 million years ago Pangea began to break up,
isolating the continents
Continental
Drift
V. Mass Extinctions
A. Earth had relatively long periods of
stability broken by brief episodes of great
species loss known as mass extinctions
B. Extinctions occur all the time but
there have been five or six distinct
periods of mass extinction over the last
600 million years
C. After every extinction the surviving
organisms have a new opportunity to
change
15.4 Modern taxonomy reflects
evolutionary history
I. What is Taxonomy?
A. Taxonomy involves the naming
and classification of organisms
B. The goal is to reduce confusion
and organize life into larger groups
or related species
Classification
II. The Linnaean System of
Classification
A. Carolus Linnaeus developed a
system that uses a two part Latin name
for each species and a hierarchy of
species into broader groups
B. The two part name is binomial
which means the first name is the
genus and the second name is the
species
Kingdoms
5 Kingdoms
•
•
•
•
•
•
Monera - bacteria (prokaroyote)
Protista- amoeba (single cell)
Animal- platypus
Plant- fern
Fungi- mushroom
Virus (Non-living?) a kingdom?
III. Classification and Evolution
A. A diagram that reflects evolutionary
relationships has a branching pattern called
a phylogenetic tree
B. Convergent Evolution is a process in
which unrelated species from similar
environments have adaptations that seem
similar
C. Similar adaptations that result from
convergent evolution are called analogous
structures
Phylogenic
Tree
Classification Groups
(Linnanean)
• Kingdom (largest 5 of them) -->
Phylum --> Class --> Order -->
Family --> Genus --> Species
(millions of them)
5 Kingdom / 3 Domain
IV. Molecular Data as a
Taxonomic Tool
A. The relatedness of species can
be measured by comparing genes
and gene products
B. This evidence is independent of
structural data
V. Cladistics
A. Cladistics is the scientific search for
ancestral relationships among species
B. Each branch on a cladogram is called a
clade; every clade consists of an ancestral
species and all of its descendants
C. Derived characters are homologous
characteristics that unite the organisms as
a group
Cladogram
Cladogram
VI. Comparing Classification
Schemes
A. The Kingdom is the broadest
taxonomic category
B. Biologists have gone from a twokingdom system, three-kingdom
system, five-kingdom system and now
to a three domain system
Re-examining Classification
Redi’s
Experiment