1. Evolution and Biodiversity
Chapter 4

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?

3. Chapter Overview Questions (cont’d)
What is an ecological niche, and how does it help a population adapt to changing environmental conditions?
How do extinction of species and formation of new species affect biodiversity?

4. Video: Creation vs. Evolution
Videos\creation_evolution.flv -
From ABC News, Environmental Science in the Headlines, 2005 DVD.

5. 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
Fig. 4-3, p. 84

6. 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

7. What is Evolution?
Biological Evolution: change in a population’s genetic makeup (gene pool) through successive generations.
Populations, NOT individuals, evolve by becoming genetically different
Microevolution: small genetic changes that occur in a population
Macroevolution: long-term, large-scale evolutionary changes through which new species are formed and other species are lost

8. Facts 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.

9. 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.

10. Video: Continental Drift
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VIDEO

11. Climate Change and Natural Selection
Changes in climate throughout the earth’s history have shifted where plants and animals can live.
Figure 4-6

12. 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.

13. Microevolution
Gene pool
Alleles
Mutations
Natural selection

14. What are three types of natural selection?
Directional natural selection: changing environmental conditions cause individuals with traits at one end of the normal range become more common than midrange forms.
Example: evolution of genetic resistance to pesticides among insects and to antibiotics among disease-carrying bacteria

15. Second type of natural selection
Stabilizing natural selection: tends to eliminate individuals on both ends of the genetic spectrum and favor individuals with an average genetic makeup.
Occurs when an environment changes little, and most members of the population are well adapted to that environment

16. Third type of natural selection
Diversifying natural selection: occurs when environmental conditions favor individuals at both extremes of the genetic spectrum and eliminate or sharply reduce number of individuals with normal genetic traits.
A population is split into two groups.

18. Animation: Stabilizing Selection
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ANIMATION

19. Animation: Diversifying Selection
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ANIMATION

20. Animation: Moth Populations
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ANIMATION

21. Animation: Adaptive Trait
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ANIMATION

22. 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 a fertile offspring.
Some species (mostly microorganisms) can exchange genes without sexual reproduction.
Horizontal gene transfer

23. What is Coevolution?
Coevolution is used to describe cases where two (or more) species reciprocally affect each other’s evolution. So for example, an evolutionary change in the morphology of a plant, might affect the morphology of an herbivore that eats the plant, which in turn might affect the evolution of the plant, which might affect the evolution of the herbivore...and so on.

24. Ecological Niches and Adaptation
Ecological niche: species functional role in an ecosystem.
Involves range of tolerance for various physical and chemical conditions (water availability, for example)
Types and amounts of resources it uses, such as food or nutrients
How it interacts with other living and nonliving components of the ecosystem
The role it plays in the energy flow and matter cycling in the ecosystem

25. How is the niche different from a habitat?
The niche is like a species’ occupation, whereas the habitat is like its address
The niche represents the adaptations or adaptive traits that its members have acquired through evolution

26. What is the difference between a species’ fundamental niche and its realized niche?
The fundamental niche is the full potential range of conditions and resources it could use if there were no competition from other species
The realized niche is the part of the fundamental niche in a community or ecosystem that the species actually occupies

27. Generalist vs. Specialist Species
Generalist species: have broad niches
Can live in many different places
Eat a variety of foods
Tolerate a wide range of environmental conditions
Rats, mice, white-tailed deer, cockroaches, flies
Specialist species: have narrow niches
Live in only one type of habitat
Use only one or a few types of food
Tolerate only a narrow range of climatic and other environmental conditions
Makes them more prone to extinction when conditions change
Tiger salamander, red-cockaded woodpeckers, spotted owls

28. 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

29. Specialized Feeding Niches
Resource partitioning reduces competition and allows sharing of limited resources.
Figure 4-8

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
Fig. 4-9, p. 91

31. What limits adaptation?
A change in environmental conditions
Reproductive capacity.
Quickly reproducing populations adapt in a short time
Slowly reproducing populations take a long time to adapt through natural selection
Most of the population has to die or become sterile so individuals with the desirable trait could predominate and pass the trait on.

32. Different species of bowerbird construct elaborate bowers and decorate them with different colors in order to woo females. The Satin bowerbird (left) builds a channel between upright sticks, and decorates with bright blue objects, while the MacGregor’s Bowerbird (right) builds a tall tower of sticks and decorates with bits of charcoal. Evolutionary changes in mating rituals, such as bower construction, can contribute to speciation.

33. Speciation, Extinction, and Biodiversity
Speciation: when two species arise from one.
Geographic isolation: groups of the same population of a species become physically separate for long periods
Part of the population migrates
Population separated by a physical barrier
Population separated by volcanic eruption or earthquake
A few individuals are carried to a new location by wind or water

34. Speciation
Reproductive isolation: mutation and natural selection operate independently in two geographically isolated populations and change the gene pools in different ways (called divergent evolution).

35. 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
Fig. 4-10, p. 92

36. 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. Reason?
Figure 4-11

37. How do species become extinct?
Extinction is the second process affecting the number and types of species on the earth
When environmental conditions change, a species must
Evolve, or become better adapted
Move to a more favorable environment, if possible
Cease to exist (become extinct)

38. 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
Fig. 4-12, p. 93

39. Earth’s long-term patterns of speciation and extinction
Affected by:
Large-scale movements of the continents
Gradual climate changes caused by continental drift and slight shifts in the earth’s orbit around the sun
Rapid climate change caused by catastrophic events (such as large volcanic eruptions, huge meteorites and asteroids crashing into earth)

40. Types of Extinction Background extinction Mass extinction
Mass depletion
Adaptive radiations

41. Effects of Humans on Biodiversity
The scientific consensus is that human activities are decreasing the earth’s biodiversity.
Figure 4-13

42. How do speciation and extinction affect biodiversity
Speciation minus extinction equals biodiversity
Mass extinction and mass depletions temporarily reduce biodiversity
Also create evolutionary opportunities
Much evidence indicates that humans have become a major force in premature extinction of species
During the 20th century, extinction rates increased by times the natural background rate

43. 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

44. Genetic Engineering: Genetically Modified Organisms (GMO)
GMOs use recombinant DNA
genes or portions of genes from different organisms.
Figure 4-14

45. Animation: Transgenic Plants
PLAY
ANIMATION
From ABC News, Biology in the Headlines, 2005 DVD.

46. 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.

47. 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?