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Chapter 4
Evolution and
Biodiversity
Chapter 6
Evolution and Biodiversity
What is biodiversity?
*Biodiversity is the variety of earth’s species, the genes
they contain, the ecosystems in which they live, and the
ecosystem processes such as energy flow and nutrient
cycling that sustain all life.
Components………
species diversity
genetic diversity
ecosystem diversity
functional diversity
Importance of species diversity
species richness – number of different species
 species evenness- relative abundance of
individuals within each of those species
 species diversity varies with geographic location
 species rich ecosystems are productive and
sustainable

Core Case Study
Earth: The Just-Right, Adaptable
Planet
 During
the 3.7 billion
years since life
arose, the average
surface temperature
of the earth has
remained within the
range of 10-20oC.
Figure 4-1
Biological
Change
 This
has led to
the variety of
species we
find on the
earth today.
 If the earth
was only 1 day
old……
Figure 4-2
How Do We Know Which Organisms
Lived in the Past?
 Our
knowledge
about past life
comes from fossils,
chemical analysis,
cores drilled out of
buried ice, and DNA
analysis.
Figure 4-4
NATURAL SELECTION, AND
ADAPTATION
 Biological
change by natural selection
involves the change in a population’s genetic
makeup through successive generations.


genetic variability
Mutations: random changes in the structure or
number of DNA molecules in a cell that can be
inherited by offspring.
Natural Selection and Adaptation:
Leaving More Offspring With
Beneficial Traits
 Three
conditions are necessary for biological
change:

Genetic variability, traits must be heritable, trait
must lead to differential reproduction.
 An
adaptive trait is any heritable trait that
enables an organism to survive through
natural selection and reproduce better under
prevailing environmental conditions.
Coevolution: A Biological Arms Race
 Interacting
species can engage in a back and
forth genetic contest in which each gains a
temporary genetic advantage over the other.

This often happens between predators and prey
species.
Hybridization and Gene Swapping:
other Ways to Exchange Genes
 New

species can arise through hybridization.
Occurs when individuals to two distinct species
crossbreed to produce an fertile offspring. (fairly
rare…)
 Some
species (mostly microorganisms) can
exchange genes without sexual reproduction.

Horizontal gene transfer
Limits on Adaptation through
Natural Selection
A
population’s ability to adapt to new
environmental conditions through natural
selection is limited by its gene pool and how
fast it can reproduce.

Humans have a relatively slow generation time
(decades) and output (# of young) versus some
other species.
Common Myths about Natural
Selection
 Evolution
through natural selection is about
the most descendants.


Organisms do not develop certain traits because
they need them. Mutations are random.
There is no such thing as genetic perfection. It is
always possible for a mutation to occur which will
lead to better natural selection.
GEOLOGIC PROCESSES, CLIMATE
CHANGE, CATASTROPHES, AND
EVOLUTION
 The
movement of solid (tectonic) plates
making up the earth’s surface, volcanic
eruptions, and earthquakes can wipe out
existing species and help form new ones.


The locations of continents and oceanic basins
influence climate.
The movement of continents have allowed
species to move.
225 million years ago
65 million years ago
135 million years ago
Present
Fig. 4-5, p. 88
Climate Change and Natural
Selection
 Changes
in climate throughout the earth’s
history have shifted where plants and
animals can live.
Figure 4-6
Catastrophes and Natural Selection
 Asteroids
and meteorites hitting the earth and
upheavals of the earth from geologic
processes have wiped out large numbers of
species and created evolutionary
opportunities by natural selection of new
species.
ECOLOGICAL NICHES AND
ADAPTATION

Each species in an ecosystem has a specific role or
way of life.
 Ecological niche is the sum total of a species’ use
of the biotic and abiotic resources in the
environment.


Fundamental niche: the full potential range of physical,
chemical, and biological conditions and resources a
species could theoretically use.
Realized niche: to survive and avoid competition, a
species usually occupies only part of its fundamental
niche.
Generalist and Specialist Species:
Broad and Narrow Niches
 Generalist
species tolerate
a wide range of
conditions.
 Specialist
species can
only tolerate a
narrow range of
conditions.
Figure 4-7
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 massive
radiation.
Figure 4-A
Specialized Feeding Niches
 Resource
partitioning reduces competition
and allows sharing of limited resources.
Figure 4-8
Some General Types of Species...
 Native
species: species that normally
live & thrive in a particular ecosystem.
 Nonnative
species, Exotic species,
Alien species: other species that
migrate into an ecosystem or are
introduced into an ecosystem by
humans.
Frogs Galore

From ABC News, Environmental Science in the Headlines, 2005 DVD.
Some general species continued...
 Indicator
species: species that serve as early
warnings that a community or an ecosystem
is being damaged.
Some general species continued...
 Keystone
Species: species that play roles
affecting many other organisms in an
ecosystem.
* Dung beetle
* Sea otters
* Gopher tortoises
* Bats
SPECIATION, EXTINCTION, AND
BIODIVERSITY
 Speciation:
A new species can arise when
member of a population become isolated for
a long period of time.

Genetic makeup changes, preventing them from
producing fertile offspring with the original
population if reunited.
Geographic Isolation
 …can
lead to reproductive isolation,
divergence of gene pools and speciation.
Figure 4-10
Extinction: Lights Out
 Extinction
occurs
when the
population
cannot adapt to
changing
environmental
conditions.
The
golden toad of Costa Rica’s
Monteverde cloud forest has
become extinct because of
changes in climate.
Figure 4-11
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
Effects of Humans on Biodiversity
 The
scientific consensus is that human
activities are decreasing the earth’s
biodiversity.
Figure 4-13
GENETIC ENGINEERING AND THE
FUTURE OF EVOLUTION
 We
have used artificial selection to change
the genetic characteristics of populations with
similar genes through selective breeding.
 We
have used
genetic engineering
to transfer genes
from one species to
another.
Figure 4-15
Genetic Engineering:
Genetically Modified Organisms (GMO)
 GMOs
use
recombinant
DNA

genes or portions
of genes from
different
organisms.
Figure 4-14
Phase 2
Make Transgenic Cell
E. Coli A. tumefaciens
(agrobacterium)
Foreign DNA
Plant cell
Host DNA
Nucleus
Transfer plasmid
copies to a carrier
agrobacterium
Transfer plasmid to
surface of microscopic
metal particle
Agrobacterium inserts
foreign DNA into plant cell
to yield transgenic cell
Use gene gun to inject
DNA into plant cell
Fig. 4-14, p. 95
Phase 3
Grow Genetically Engineered Plant
Transgenic cell
from Phase 2
Cell division of
transgenic cells
Culture cells
to form plantlets
Transfer
to soil
Transgenic plants
with new traits
Fig. 4-14, p. 95
Phase 3
Grow Genetically
Engineered Plant
Transgenic cell
from Phase 2
Cell division of
transgenic cells
Culture cells
to form plantlets
Transfer to soil
Transgenic plants
with new traits
Stepped Art
Fig. 4-14, p. 95
THE FUTURE OF EVOLUTION
 Biologists
are learning to rebuild organisms
from their cell components and to clone
organisms.

Cloning has lead to high miscarriage rates, rapid
aging, organ defects.
 Genetic
engineering can help improve human
condition, but results are not always
predictable.

Do not know where the new gene will be located
in the DNA molecule’s structure and how that will
affect the organism.
Cloned Pooch

From ABC News, Biology in the Headlines, 2005 DVD.
Controversy Over
Genetic Engineering
 There
are a number of privacy, ethical, legal
and environmental issues.
 Should genetic engineering and development
be regulated?
 What are the long-term environmental
consequences?
Case Study:
How Did We Become Such a Powerful
Species so Quickly?
 We



lack:
strength, speed, agility.
weapons (claws, fangs), protection (shell).
poor hearing and vision.
 We
have thrived as a species because of
our:

opposable thumbs, ability to walk upright,
complex brains (problem solving).