Transcript ch 4 text ppt

Chapter 4
Evolution and
Biodiversity
Evolution
 Microevolution
Change over time in genetic make up of a
species
 Macroevolution (biological evolution)
 Change over time from one organism to
another
 Theory of Evolution
 Macroevolution
 Natural selection

When talking about Evolution
Please remember
Not
everything
you read
about
Evolution is
true.
There
is a
lack of
evidence to
support
Biological
Evolution.
When talking about Evolution
Please remember
A belief in evolution
undermines the Bible and
Christianity as a whole.

Chapter 4
Natural Selection and
Biodiversity
Why Should We Care About
Biodiversity?
 Biodiversity
provides us with:
 Natural Resources (food water, wood,
energy, and medicines)
 Natural Services (air and water
purification, soil fertility, waste
disposal, pest control)
 Aesthetic pleasure
NATURAL SELECTION AND
ADAPTATION
 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.
I regard gene mutation as a very
logical and possible occurrence but
I do not think that it is, in view of
the stability of the gene, as
important a factor in speciation as
its proponents contend. I would
also like to emphasize that there
are other methods of speciation
such as polyploidy and
hybridization
Irving W. Knobloch, Ph.D
"It may, in short, be stated that no
mutation has ever occurred in the
progress of genetic work which is
fully viable and behaves as a
dominant to the wild-type
condition. That any have given
rise to changes which could be of
survival value in nature appears
highly doubtful". E. B. Ford,
Mendelism and Evolution, Dial Press, N. Y., 193L
"Mutation changes one gene at a
time; simultaneous mutation of
masses of genes is unknown. On the
other hand, species differ from each
other usually in many genes; hence,
a sudden origin of a species by
mutation, in one thrust, would
demand a simultaneous mutation of
numerous genes."
Theodosius Dobzhansky,
Genetics and the Origin of Species, 2nd Ed., Columbia Univ.
Press, 1941
"Although a great many species
have been studied, it must be
admitted that most of them are
not in a “mutating” condition.
Thus if mutation is not a general
phenomenon, it can have but
slight significance as a means of
species formation"
Arthur W. Haupt,
Fundamentals of Biology, McGraw Hill Book Co., N. Y., 1928.
Hybridization and Gene Swapping:
other Ways to Exchange Genes
 New
species arise through hybridization.
 Occurs when individuals of 2 distinct
species crossbreed to produce a fertile
offspring.
 Some species (mostly microorganisms)
can exchange genes without sexual
reproduction.
 Horizontal gene transfer
Geographic Isolation
 …can
lead to reproductive isolation,
divergence of gene pools and speciation.
Figure 4-10
Climate Change and Natural
Selection
 Changes
in climate throughout the earth’s
history have shifted where plants and
animals can live.
Figure 4-6
Natural Selection and Adaptation:
Leaving More Offspring With
Beneficial Traits
 Three



conditions are necessary :
Genetic variability
traits must be heritable
trait must lead to differential
reproduction.
Natural Selection and Adaptation:
Leaving More Offspring With
Beneficial Traits
 An


adaptive trait is any heritable trait that
enables an organism to survive through
natural selection and
reproduce better under prevailing
environmental conditions.
Natural Selection: 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.
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
 Natural
selection is not about survival of the
fittest.
 It is about the most descendants.
 Organisms do not develop certain traits
because they need them.
 It is a completely random process.
 There is no such thing as genetic
perfection.
SPECIATION, EXTINCTION, AND
BIODIVERSITY
 Endemic
species
 Found in only one place
 Vulnerable to extinction
 Background extinction
 Low rate of disappearance
 Mass extinction
 Significant rise in disappearance rate
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
SPECIATION, EXTINCTION, AND
BIODIVERSITY
 Richness
Number of different species
 Evenness
 Relative abundance of individuals
within each species

ECOLOGICAL NICHES AND
ADAPTATION
 Each
species in an ecosystem has a specific
role or way of life.
 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
Number of individuals
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Fig. 4-7, p. 91
SPOTLIGHT
Cockroaches: Nature’s Ultimate
Survivors
 3,500
different species
 Ultimate generalist



Can eat almost anything.
Can live and breed almost
anywhere.
Can withstand massive
radiation.
Figure 4-A
ECOLOGICAL NICHES AND
ADAPTATION
 Native

Normally live in the environment
 Non


species
native species
Accidentally introduced to the environment
Invasive or alien species
 Indicator

species
Provide an early warning of damage
ECOLOGICAL NICHES AND
ADAPTATION
 Keystone


species
Have a large effect on types and abundance of
other organisms
Have critical roles in the environment
 Foundation

species
Shape communities by creating & enhancing
habitats
Specialized Feeding Niches
 No
two organisms can share the exact
same Niche in the exact same place
 Resource partitioning reduces competition
and allows sharing of limited resources.
Figure 4-8
Avocet sweeps bill through
mud and surface water in
search of small crustaceans,
insects, and seeds
Ruddy
turnstone
Herring gull is a
searches
tireless scavenger
under shells
and pebbles
Dowitcher probes deeply
for small
into mud in search of
invertebrates
snails, marine worms,
and small crustaceans
Brown pelican
dives for fish,
which it locates
from the air
Black skimmer
seizes small fish
at water surface
Louisiana heron wades into
water to seize small fish
Flamingo
feeds on
minute
organisms
in mud
Scaup and other
diving ducks feed
on mollusks,
crustaceans,and
aquatic vegetation
(Birds not drawn to scale)
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Knot (a sandpiper)
picks up worms and
small crustaceans left
by receding tide
Fig. 4-8, pp. 90-91
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 1
Make Modified Gene
E. coli
Cell
Extract DNA
Gene of
interest
DNA
Identify and
Identify and
remove portion
extract gene
of DNA with
with desired trait
desired trait
Extract
Plasmid
Genetically
modified
plasmid
Insert modified
plasmid into E. coli
Plasmid
Remove
Insert extracted
plasmid
(step 2) into plasmid
from DNA of
(step 3)
E. coli
Grow in tissue
culture to
make copies
Fig. 4-14, p. 95
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
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?
THE FUTURE
 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.
How Would You Vote?
 Should
we legalize the production of human
clones if a reasonably safe technology for
doing so becomes available?
 a. No. Human cloning will lead to
widespread human rights abuses and
further overpopulation.
 b. Yes. People would benefit with longer
and healthier lives.