Transcript Power point on evolution

Chapter 5
Evolution of Biodiversity
Which was the
earliest form of life?
a.
b.
c.
d.
e.
The eukaryotic cell
The protocell
The prokaryotic cell
The amino acid
The RNA
Biodiversity
Biodiversity
increases with speciation
decreases with extinction
Give-and-take between speciation and extinction
 changes in biodiversity
Extinction creates evolutionary opportunities for
adaptive radiation of surviving species
Earth is home to a tremendous
diversity of species
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Ecosystem diversity- the variety of ecosystems
within a given region.
Species diversity- the variety of species in a given
ecosystem.
Genetic diversity- the variety of genes within a
given species.
Types of Diversity
Which does not belong?
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A. Situational
B. Ecosystem
C. Genetic
D. species
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Species richness- the number of species in a
given area.
Species evenness- the measure of whether a
particular ecosystem is numerically
dominated by one species or are all
represented by similar numbers of
individuals.
Evolution is the mechanism
underlying biodiversity
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Evolution- a change in the genetic
composition of a population over time.
Microevolution- evolution below the
species level.
Macroevolution- Evolution which gives
rise to new species or new genera, family,
class or phyla.
Evolution is the mechanism
underlying biodiversity
•
MacroevolutionEvolution which
gives rise to new
species or new
genera, family,
class or phyla.
Speciation
• Happens when there is reproductive
isolation between 2 populations
• May be because of geographics,
behavioral, or temporal issues
Evolution by artificial selection
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Evolution by artificial selection- when humans
determine which individuals breed..
Evolution by natural
selection
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Evolution by natural selectionthe environment determines
which individuals are most
likely to survive and
reproduce.
Darwin’s theory of evolution by
natural selection
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Individuals produce an excess of offspring.
Not all offspring can survive.
Individuals differ in their traits.
Differences in traits can be passed on from
parents to offspring.
Differences in traits are associated with
differences in the ability to survive and
reproduce.
Which of the following statements
does not belong to the theory of
Natural Selection?
• A.
• B.
More species are made than survive
N.S. happens when a particular
breed of dog is created by Man.
• C.
The best adapted organism survives
in order to reproduce more of its kind.
• D.
According to N.S. theory, the less fit
do not survive, therefore, do not evolve.
Specialized Feeding
Niches
• Resource partitioning reduces
competition and allows sharing of
limited resources.
Figure 4-8
Evolution shapes ecological niches
and determines species distributions
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Range of tolerance- all species have an optimal
environment in which it performs well. The limit to the
abiotic conditions they can tolerate is known as the
range of tolerance.
Fundamental niche- the ideal conditions for a species.
Full potential of physical, chemical, and biological
conditions an organism could use.
Realized niche- the real part of the niche that an
organism occupies to avoid and survive competition.
Niches
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Realized niche- the range of abiotic and biotic
conditions under which a species lives. This
determines the species distribution, or areas of the
world where it lives.
Niche generalist- species that live under a wide
range of conditions.
Niche specialist- species that live only in specific
habitats.
• Generalist
species
tolerate a
wide range
of
conditions.
• Specialist
species can
only tolerate
a narrow
range of
conditions. Figure 4-7
Adaptive
Radiation
•Emergence of numerous
species from a common
ancestor introduced to
new and diverse
environments.
•Example:
•Hawaiian
Honeycreepers
The Fossil Record
• Fossils- remains of organisms that have
been preserved in rock. Much of what
we know about evolution comes from
the fossil record.
SPOTLIGHT
Cockroaches: Nature’s Ultimate Survivors
• 350 million years old
• 3,500 different
species
• Ultimate generalist
• Can eat almost
anything.
• Can live and breed
almost anywhere.
• Can withstand
Figure 4-A
Which type of species is
the cockroach?
• A. Generalist species
• B. Specialist species
• C. Naturalist species
Cenozoic
Era
Period
Millions of
years ago
Quaternary
Today
Tertiary
65
Mesozoic
Cretaceous
Jurassic
180
Triassic
Species and families
experiencing
mass extinction
Extinction Current extinction crisis caused
by human activities. Many species
are expected to become extinct
Extinction within the next 50–100 years.
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Extinction
Triassic: 35% of animal families,
including many reptiles and marine
mollusks.
Bar width represents relative
number of living species
250
Extinction
345
Extinction
Permian
Paleozoic
Carboniferous
Devonian
Permian: 90% of animal families,
including over 95% of marine
species; many trees, amphibians,
most bryozoans and brachiopods,
all trilobites.
Devonian: 30% of animal
families, including agnathan and
placoderm fishes and many
trilobites.
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician: 50% of animal
families, including many
trilobites.
Fig. 4-12, p. 93
At any given moment (e.g. the
‘present’), all we see is
current diversity…
all extinct forms are gone
(99.9%)
The Sixth Mass Extinction
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Scientists feel that we are in our sixth mass
extinction, occurring in the last two decades.
Estimates of extinction rates vary widely, from
2 % to 25% by 2020.
In contrast to previous mass extinctions,
scientists agree that this one is caused by
humans.