1. Evolution and Biodiversity
Chapter 3
Evolution and Biodiversity

2. 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?

3. 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?

4. Updates Online
The 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 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

5. 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.

6. 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.

7. ORIGINS OF LIFE
1 billion years of chemical change to form the first cells, followed by about 3.7 billion years of biological change.

8. Chemical Evolution Biological Evolution (1 billion years)
Formation
of the
earth’s
early
crust and
atmosphere
Variety of
multicellular
organisms
form, first
in the seas
and later
on land
Large
organic molecules
(biopolymers)
form in
the seas
First
protocells form in the seas
Single-cell prokaryotes
form in
the seas
Single-cell
eukaryotes
form in
the seas
Small organic
molecules
form in
the seas
Figure 4.2
Natural capital: summary of the earth’s hypothesized chemical and biological evolution by natural selection. This drawing is not to scale. Note that the time span for biological evolution by natural selection is almost four times longer than that for chemical evolution.

9. Biological Evolution
This has led to the variety of species we find on the earth today.
Figure 4-2

10. Recorded human history begins about 1/4 second before midnight
Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnight
Recorded human history begins about 1/4 second before midnight
Age of mammals
Age of reptiles
Insects and amphibians invade the land
Origin of life ( billion years ago)
Figure 4.3
Natural capital: greatly simplified overview of the biological evolution by natural selection of life on the earth, which was preceded by about 1 billion years of chemical evolution. Microorganisms (mostly bacteria) that lived in water dominated the early span of biological evolution on the earth, between about 3.7 billion and 1 billion years ago. Plants and animals evolved first in the seas. Fossil and recent DNA evidence suggests that plants began invading the land some 780 million years ago, and animals began living on land about 370 million years ago. Humans arrived on the scene only a very short time ago—equivalent to less than an eye blink of the earth’s roughly 3.7-billion-year history of biological evolution.
First fossil record of animals
Plants begin invading land
Evolution and expansion of life

11. 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.

12. 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.

13. 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.

14. 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.

15. 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

16. 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.

17. 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.

18. 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.

19. 225 million years ago 225 million years ago 135 million years ago
Figure 4.5
Geological processes and biological evolution. Over millions of years the earth’s continents have moved very slowly on several gigantic tectonic plates. This process plays a role in the extinction of species as land areas split apart and promote the rise of new species when once isolated land areas combine. Rock and fossil evidence indicates that 200–250 million years ago all of the earth’s present-day continents were locked together in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s huge plates separated and eventually resulted in today’s locations of the continents (bottom right).
65 million years ago
Present

20. Climate Change and Natural Selection
Changes in climate throughout the earth’s history have shifted where plants and animals can live.

21. Northern Hemisphere Ice coverage
18,000
years before present
Northern Hemisphere
Ice coverage
Modern day
(August)
Note:
Modern sea ice coverage
represents
summer months
Legend
Continental ice
Figure 4.6
Changes in ice coverage in the northern hemisphere during the past 18,000 years. (Data from the National Oceanic and Atmospheric Administration)
Sea ice
Land above sea level

22. 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.

23. 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.

24. 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.

25. Specialist species Generalist species with a narrow niche
with a broad niche
Niche
separation
Number of individuals
Figure 4.7
Overlap of the niches of two different species: a specialist and a generalist. In the overlap area, the two species compete for one or more of the same resources. As a result, each species can occupy only a part of its fundamental niche; the part it occupies is its realized niche. Generalist species such as a raccoon have a broad niche (right), and specialist species such as the giant panda have a narrow niche (left).
Niche
breadth
Region of
niche overlap
Resource use

26. 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.

27. Specialized Feeding Niches
Resource partitioning reduces competition and allows sharing of limited resources.

28. Avocet sweeps bill through mud and surface water in
search of small crustaceans,
insects, and seeds
Ruddy turnstone searches
under shells and pebbles
for small invertebrates
Herring gull is a
tireless scavenger
Brown pelican dives for fish,
which it locates from the air
Dowitcher probes deeply
into mud in search of
snails, marine worms,
and small crustaceans
Black skimmer
seizes small fish
at water surface
Louisiana heron wades into
water to seize small fish
Figure 4.8
Natural capital: specialized feeding niches of various bird species in a coastal wetland. Such resource partitioning reduces competition and allows sharing of limited resources.
Piping plover feeds
on insects and tiny
crustaceans on
sandy beaches
Oystercatcher feeds on
clams, mussels, and
other shellfish into which
it pries its narrow beak
Flamingo
feeds on
minute
organisms
in mud
Scaup and other
diving ducks feed on mollusks, crustaceans,and aquatic vegetation
Knot (a sandpiper)
picks up worms and
small crustaceans left
by receding tide
(Birds not drawn to scale)

29. Evolutionary Divergence
Each species has a beak specialized to take advantage of certain types of food resource.

30. Insect and nectar eaters
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Kona Grosbeak
Crested Honeycreeper
Akiapolaau
Figure 4.9
Natural capital: evolutionary divergence of honeycreepers into specialized ecological niches. Each species has a beak specialized to take advantage of certain types of food resources.
Maui Parrotbill
Apapane
Unknown finch ancestor

31. 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.

32. Geographic Isolation
…can lead to reproductive isolation, divergence of gene pools and speciation.

33. matches snow for camouflage.
Adapted to cold through heavier fur,short ears, short legs,short nose. White fur
matches snow for camouflage.
Arctic Fox
Northern
population
Early fox
Population
Spreads
northward
and southward
and separates
Different environmental
conditions lead to different selective pressures and evolution into two different species.
Adapted to heat through lightweight
fur and long ears, legs, and nose, which give off more heat.
Southern
Population
Figure 4.10
Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation.
Gray Fox

34. 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.

35. Species and families experiencing mass extinction
Bar width represents relative
number of living species
Millions of
years ago
Era
Period
Extinction
Current extinction crisis caused
by human activities. Many species
are expected to become extinct
within the next 50–100 years.
Quaternary
Today
Cenozoic
Tertiary
Extinction 65
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Cretaceous
Mesozoic
Jurassic
Extinction
Triassic: 35% of animal families, including many reptiles and marine mollusks.
180
Triassic
Extinction
Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites.
250
Permian
Carboniferous
Extinction
345
Figure 4.12
Fossils and radioactive dating indicate that five major mass extinctions (indicated by arrows) have taken place over the past 500 million years. Mass extinctions leave many organism roles (niches) unoccupied and create new niches. Each mass extinction has been followed by periods of recovery (represented by the wedge shapes) called adaptive radiations. During these periods, which last 10 million years or longer, new species evolve to fill new or vacated niches. Many scientists say that we are now in the midst of a sixth mass extinction, caused primarily by human activities.
Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites.
Devonian
Paleozoic
Silurian
Ordovician
Extinction
500
Ordovician: 50% of animal families, including many trilobites.
Cambrian

36. Effects of Humans on Biodiversity
The scientific consensus is that human activities are decreasing the earth’s biodiversity.

37. Silurian Permian Jurassic Cambrian Ordovician Devonian Devonian
Terrestrial
organisms
Silurian
Permian
Jurassic
Cambrian
Ordovician
Devonian
Devonian
Cretaceous
Pre-cambrian
Marine
organisms
Carboniferous
Number of families
Tertiary
Quaternary
Figure 4.13
Natural capital: changes in the earth’s biodiversity over geological time. The biological diversity of life on land and in the oceans has increased dramatically over the last 3.5 billion years, especially during the past 250 million years. During the last 1.8 million years this increase has leveled off.
Millions of years ago

38. 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.

39. Genetic Engineering: Genetically Modified Organisms (GMO)
GMOs use recombinant DNA
genes or portions of genes from different organisms.

40. Identify and remove portion of DNA with
Phase 1
Make Modified Gene
E. coli
Genetically
modified
plasmid
Insert modified
plasmid into E. coli
Cell
Extract
Plasmid
Extract DNA
Plasmid
Gene of
interest
DNA
Identify and remove portion of DNA with
desired trait
Remove plasmid
from DNA of E. coli
Insert extracted
(step 2) into plasmid
(step 3)
Identify and extract gene with desired trait
Grow in tissue
culture to
make copies
Figure 4.14
Genetic engineering: steps in genetically modifying a plant.

41. Transfer plasmid copies to a carrier agrobacterium
Phase 2
Make Transgenic Cell
A. tumefaciens
(agrobacterium)
Foreign DNA
E. Coli
Host DNA
Plant cell
Nucleus
Transfer plasmid copies to a carrier agrobacterium
Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell
Figure 4.14
Genetic engineering: steps in genetically modifying a plant.
Transfer plasmid to surface of microscopic metal particle
Use gene gun to inject
DNA into plant cell

42. Grow Genetically Engineered Plant
Phase 3
Grow Genetically Engineered Plant
Transgenic cell
from Phase 2
Cell division of
transgenic cells
Culture cells
to form plantlets
Figure 4.14
Genetic engineering: steps in genetically modifying a plant.
Transfer to soil
Transgenic plants
with new traits

43. Transgenic cell
from Phase 2
Phase 3
Grow Genetically Engineered Plant
Cell division of
transgenic cells
Culture cells
to form plantlets
Transfer to soil
Transgenic plants
with new traits
Stepped Art

44. 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.

45. 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.

46. 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?

47. 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).