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Chapter 5. Evolution and Biodiversity. Chapter Overview Questions. How do scientists account for the development of life on earth? What is biological evolution by natural selection, and how can it account for the current diversity of organisms on the earth? - PowerPoint PPT PresentationTRANSCRIPT
Chapter 5
Evolution and Biodiversity
Chapter Overview Questions How do scientists account for the
development of life on earth? What is biological evolution by natural
selection, and how can it account for the current diversity of organisms on the earth?
How can geologic processes, climate change and catastrophes affect biological evolution?
What is an ecological niche, and how does it help a population adapt to changing the environmental conditions?
Chapter Overview Questions (cont’d)
How do extinction of species and formation of new species affect biodiversity?
What is the future of evolution, and what role should humans play in this future?
How did we become such a powerful species in a short time?
Updates OnlineThe latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles.
InfoTrac: Life After Earth: Imagining Survival Beyond This Terra Firma. Richard Morgan. The New York Times, August 1, 2006 pF2(L).
InfoTrac: Rhinos Clinging to Survival in the Heart of Borneo, Despite Poaching. US Newswire, March 17, 2006.
InfoTrac: Newfound Island Graveyard May Yield Clues to Dodo Life of Long Ago. Carl Zimmer. The New York Times, July 4, 2006 pF3(L).
NASA: Evolvable Systems American Museum of Natural History: Tree of Life PBS: Evolution
Video: Creation Vs. Evolution
This video clip is available in CNN Today Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local sales representative to order this volume, while supplies last.
Core Case StudyEarth: 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
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
Fig. 4-2, p. 84
Variety ofmulticellularorganismsform, firstin the seasand lateron land
Biological Evolution(3.7 billion years)
Chemical Evolution(1 billion years)
Formationof the
earth’searly
crust andatmosphere
Small organic
moleculesform in
the seas
Large organic
molecules(biopolymers)
form in the seas
First protocells form in the
seas
Single-cell prokaryotes
form in the seas
Single-celleukaryotes
form inthe seas
Animation: Stanley Miller’s Experiment
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Biological Evolution
This has led to the variety of species we find on the earth today.
Figure 4-2
Fig. 4-3, p. 84
Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnightRecorded human history begins about 1/4 second before midnight
Origin of life (3.6-3.8 billion years ago)
Age of mammals
Age of reptiles
Insects and amphibians invade the land
First fossil record of animals
Plants begin invading land Evolution and
expansion of life
Animation: Evolutionary Tree of Life
PLAYANIMATION
Video: Creation vs. Evolution
From ABC News, Environmental Science in the Headlines, 2005 DVD.
PLAYVIDEO
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
EVOLUTION, NATURAL SELECTION, AND ADAPTATION
Biological evolution 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.
Animation: Stabilizing Selection
PLAYANIMATION
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.
Animation: Disruptive Selection
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Animation: Moth Populations
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Animation: Adaptive Trait
PLAYANIMATION
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. 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 Evolution through Natural Selection
Evolution through natural selection is about the most descendants. 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
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
Fig. 4-5, p. 88
135 million years ago
Present65 million years ago
225 million years ago
Video: Continental Drift
PLAYVIDEO
Climate Change and Natural Selection
Changes in climate throughout the earth’s history have shifted where plants and animals can live.
Figure 4-6
Fig. 4-6, p. 89
Land above sea level
18,000years before present
Northern HemisphereIce coverage
Modern day(August)
Note:Modern sea ice
coveragerepresents
summer months
LegendContinental ice
Sea ice
Video: Dinosaur Discovery
From ABC News, Environmental Science in the Headlines, 2005 DVD.
PLAYVIDEO
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. 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
Fig. 4-7, p. 91
Generalist specieswith a broad niche
Num
ber o
f ind
ivid
uals
Resource use
Specialist specieswith a narrow niche
Nicheseparation
Nichebreadth
Region of niche overlap
SPOTLIGHTCockroaches: 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
Fig. 4-8, pp. 90-91
Piping plover feedson insects and tinycrustaceans on sandy beaches
(Birds not drawn to scale)
Black skimmerseizes small fishat water surface
Flamingofeeds on minuteorganismsin mud
Scaup and otherdiving ducks feed on mollusks, crustaceans,and aquatic vegetation
Brown pelican dives for fish,which it locates from the air
Avocet sweeps bill throughmud and surface water in search of small crustaceans,insects, and seeds
Louisiana heron wades intowater to seize small fish
Oystercatcher feeds onclams, mussels, and other shellfish into which it pries its narrow beak
Dowitcher probes deeplyinto mud in search ofsnails, marine worms,and small crustaceans
Knot (a sandpiper)picks up worms andsmall crustaceans leftby receding tide
Herring gull is atireless scavenger
Ruddy turnstone searches
under shells and pebbles
for small invertebrates
Video: Frogs Galore
From ABC News, Environmental Science in the Headlines, 2005 DVD.
PLAYVIDEO
Evolutionary Divergence
Each species has a beak specialized to take advantage of certain types of food resource.
Figure 4-9
Fig. 4-9, p. 91
Maui Parrotbill
Fruit and seed eaters Insect and nectar eaters
Kuai AkialaoaAmakihi
Crested Honeycreeper
Apapane
Akiapolaau
Unknown finch ancestor
Greater Koa-finch
Kona Grosbeak
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.
Animation: Speciation on an Archipelago
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Animation: Evolutionary Tree Diagrams
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Geographic Isolation
…can lead to reproductive isolation, divergence of gene pools and speciation.
Figure 4-10
Fig. 4-10, p. 92
Different environmentalconditions lead to different selective pressures and evolution into two different species.
SouthernPopulation
Northernpopulation
Adapted to heat through lightweightfur and long ears, legs, and nose, which give off more heat.
Adapted to cold through heavier fur,short ears, short legs,short nose. White furmatches snow for camouflage.
Gray Fox
Arctic Fox
Spreadsnorthward
and southwardand separates
Early foxPopulation
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
Fig. 4-12, p. 93
Tertiary
Bar width represents relative number of living speciesEra Period
Species and families experiencing
mass extinctionMillions ofyears ago
Ordovician: 50% of animal families, including many trilobites.
Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites.
500
345
Cambrian
Ordovician
Silurian
Devonian
Extinction
Extinction
Pale
ozoi
cM
esoz
oic
Cen
ozoi
c
Triassic: 35% of animal families, including many reptiles and marine mollusks.
Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites.Carboniferous
Permian
Current extinction crisis causedby human activities. Many speciesare expected to become extinctwithin the next 50–100 years.Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including manyforaminiferans and mollusks.
Extinction
Extinction
Triassic
Jurassic
Cretaceous
250
180
65Extinction
ExtinctionQuaternary Today
Effects of Humans on Biodiversity
The scientific consensus is that human activities are decreasing the earth’s biodiversity.
Figure 4-13
Fig. 4-13, p. 94
Marineorganisms
Terrestrialorganisms
Num
ber o
f fam
ilies
Millions of years ago
Qua
tern
ary
Tert
iary
Pre-
cam
bria
n
Cam
bria
n
Ord
ovic
ian
Silu
rian
Dev
onia
n
Car
boni
fero
us
Jura
ssic
Dev
onia
n
Perm
ian
Cre
tace
ous
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
Fig. 4-14, p. 95
Insert modifiedplasmid into E. coli
Phase 1Make Modified Gene
CellExtract DNA
E. coli
Gene ofinterest
DNA
Identify and extract gene with desired trait
Geneticallymodifiedplasmid
Identify and remove portion of DNA withdesired trait
Remove plasmidfrom DNA of E. coli
Plasmid
ExtractPlasmid
Grow in tissueculture to
make copies
Insert extracted(step 2) into plasmid
(step 3)
Fig. 4-14, p. 95
Plant cell
Phase 2Make Transgenic Cell
Transfer plasmid to surface of microscopic metal particle
Use gene gun to injectDNA into plant cell
Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell
Transfer plasmid copies to a carrier agrobacterium
Nucleus
E. Coli A. tumefaciens(agrobacterium)
Foreign DNAHost DNA
Fig. 4-14, p. 95
Cell division oftransgenic cells
Phase 3Grow Genetically Engineered Plant
Transfer to soil
Transgenic plantswith new traits
Transgenic cell from Phase 2
Culture cells to form plantlets
Fig. 4-14, p. 95
Phase 3Grow Genetically Engineered Plant
Transgenic cell from Phase 2
Cell division oftransgenic cells
Culture cells to form plantlets
Transgenic plantswith new traits
Transfer to soil
Stepped Art
Animation: Transgenic Plants
From ABC News, Biology in the Headlines, 2005 DVD.
PLAYANIMATION
How Would You Vote?
To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living In the Environment.
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
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.
Video: Cloned Pooch
From ABC News, Biology in the Headlines, 2005 DVD.
PLAYVIDEO
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).