Transcript evolution - Cloudfront.net

Chapter 4
Evolution and
Biodiversity
Core Case Study
Earth: The Just-Right, Adaptable
Planet
 3.7
billion years
since life arose
 average surface
temperature of the
earth has remained
within the range of
10-20oC
Figure 4-1
ORIGINS OF LIFE
1
billion years of chemical change to form the
first cells, followed by about 3.7 billion years
of biological change.
Figure 4-2
Animation: Stanley Miller’s Experiment
PLAY
ANIMATION
Modern humans (Homo
sapiens sapiens) appear
about 2 seconds before
midnight
Age of
mammals
Age of
reptiles
Insects and
amphibians
invade the
land
Recorded human history
begins about 1/4 second
before midnight
Origin of life
(3.6-3.8 billion
years ago)
First fossil
record of
animals
Plants
begin
invading
land
Evolution and
expansion of life
Fig. 4-3, p. 84
Animation: Evolutionary Tree of Life
PLAY
ANIMATION
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
DNA and protein
analysis
Figure 4-4
EVOLUTION, NATURAL
SELECTION, AND ADAPTATION
 Biological



evolution by natural selection
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.
Animation: Stabilizing Selection
PLAY
ANIMATION
Natural Selection and Adaptation:
Leaving More Offspring With
Beneficial Traits
 Three
conditions are necessary for biological
evolution:



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.

Survival of the Fittest
Animation: Disruptive Selection
PLAY
ANIMATION
Animation: Moth Populations
PLAY
ANIMATION
Animation: Adaptive Trait
PLAY
ANIMATION
Hybridization and Gene Swapping:
other Ways to Exchange Genes
 Hybridization


Can create new species
Occurs when individuals to two distinct species
crossbreed to produce fertile offspring
 Some
species (mostly microorganisms) can
exchange genes without sexual reproduction.

Horizontal gene transfer
Limits on Adaptation through
Natural Selection
 Changes
are limited by the population’s 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 Evolution
through Natural Selection
 Organisms
do not develop certain traits
because they need them.
 There
is no such thing as genetic perfection.
GEOLOGIC PROCESSES, CLIMATE
CHANGE, CATASTROPHES, AND
EVOLUTION
 movement


of solid (tectonic) plates causes:
volcanic eruptions
earthquakes
• can wipe out existing species and help form new ones


Species movement/relocation
locations of continents and oceanic basins
influence climate
225 million years ago
65 million years ago
135 million years ago
Present
Fig. 4-5, p. 88
Video: Continental Drift
PLAY
VIDEO
Climate Change and Natural
Selection
 Changes
in climate throughout the earth’s
history have shifted where plants and
animals can live.
Figure 4-6
Video: Dinosaur Discovery
PLAY
VIDEO

From ABC News, Environmental Science in the Headlines, 2005 DVD.
Catastrophes and Natural Selection
 Catastrophies




Asteroids and meteorites hitting the earth
upheavals of the earth from geologic processes
wipe out large numbers of species
create evolutionary opportunities by natural
selection of new species
• Adaptive radiation
ECOLOGICAL NICHES AND
ADAPTATION

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
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
Video: Frogs Galore
PLAY
VIDEO

From ABC News, Environmental Science in the Headlines, 2005 DVD.
Evolutionary Divergence
 Each
species has a
beak specialized to
take advantage of
certain types of
food resource.
Figure 4-9
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

Reproductive Isolation
Animation: Speciation on an Archipelago
PLAY
ANIMATION
Animation: Evolutionary Tree Diagrams
PLAY
ANIMATION
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
 artificial

selection
Used to change the genetic characteristics of
populations with similar genes through selective
breeding
 genetic
engineering
 Used to transfer
genes from one
species to another
 Human to
bacteria
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
Animation: Transgenic Plants
PLAY
ANIMATION

From ABC News, Biology in the Headlines, 2005 DVD.
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.
THE FUTURE OF EVOLUTION
 Cloning

rebuild organisms from their cell components
• has lead to:



high miscarriage rates
rapid aging
organ defects
 Genetic


engineering
can help improve human condition
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.
Video: Cloned Pooch
PLAY
VIDEO

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)