1. Evolution and Biodiversity
G. Tyler Miller’s
Living in the Environment
14th Edition
Chapter 5
Part 2

2. Chapter 5: Essential Questions / Objectives
Briefly describe the evolution of life from chemical evolution to the development of eukaryotic cells.
Briefly describe the theory of evolution, being sure to include the roles played by variation within the gene pool and natural selection.
Summarize and address two common misconceptions about evolution.
Define coevolution.
Define natural selection and the three conditions that are necessary for evolution of a population by natural selection.

3. Chapter 5: Essential Questions / Objectives
Describe the tools available to researchers for learning the evolutionary history of life. (evidence for evolution)
Briefly describe the theory of evolution, being sure to include the roles played by extinction, speciation, and adaptive radiation.
Distinguish between a specialist and a generalist. Evaluate the conditions that favor these two approaches.
Define ecological niche. Distinguish between condition and resource; fundamental niche and realized niche. List the factors that determine the realized niche.
Define speciation and compare allopatric speciation with sympatric speciation. Indicate which of these mechanisms is more common.

4. Define extinction and distinguish between background extinction and mass extinction. Discuss the role of humans on the rate of extinction at present.
Discuss the pros and cons of artificial selection and genetic engineering. Consider the possible environmental impacts on resource use, pollution, and environmental degradation.
Indicate what it is that has allowed humans to have such a profound influence

5. The Fossil Record as Evidence for Evolution
Fossils Skeletons, bones, shells, body parts, leaves, seeds, or impressions of such items that provide recognizable evidence of organisms that lived long ago.
Fossil of algae, Gunflint chert, 2.1 billion years old.
Brightfield X400.
Burgess Shale arthropod fossils, 530 years old,
Middle Cambrian Period.
Trilobite fossil from the Silurian period 405mya.

6. Comparative anatomy
Darwin recognized the major source of evidence for common descent was found in the concept of homology. Homology is the name given to similarity of organs or structures due to common embryonic or evolutionary origin.
Forelimbs of five vertebrates show skeletal homologies:
Yellow --- Humerus
Blue radius and ulna
Pink wrist
White ---- phalanges
Clear homologies of bones and patterns of connection are evident despite evolutionary modifications for particular functions

7. Phylogenetic Reconstruction
The phylogenetic pattern specified by 15 homologous structures in the skeletons of ratite (flightless) birds. The homologous features are numbered 1-15 and are marked both on the branches of the tree on which they arose and on the birds that them
Simplified phylogenetic reconstruction of vertebrates

9. Transitional Species
Whale evolution - the movement of the nostrils from the front of the skull to the top of the skull
Why is having the nostrils at the top of the skull an advantage?
Environmental changes require adaptations also. Organisms must be able to adapt to the new conditions, migrate to an area with a more favorable environment, or become extinct.

10. DNA Evidence for Evolution

11. Ice cores unlock climate secrets
Gases and particles trapped in the layers of an ice core provide information about the Earth's climate and atmosphere.
Oxygen and hydrogen isotopes reveal the temperature when the ice formed, for example, while high carbon dioxide and methane levels indicate periods of global warming.

12. Geological Time and Major Evolutionary Events
Modern humans
(Homo sapiens)
appear about
2 seconds
before midnight
Photosynthesis and Oxygen
Origins of the Eukaryotic Cells
The Cambrian Explosion
Movement on to land
Recorded human
history begins
1/4 second
before midnight
Age of mammals
Age of reptiles
midnight
Insects and amphibians invade the land
Origin of life
(3.6–3.8 billion
years ago)
First fossil
record of
animals
Plants begin
invading
land
noon
Evolution and expansion of life

13. Ecological Niches and Adaptation
An ecological niche is a species' way of life in an ecosystem, everything that affects its survival and reproduction.
The niche includes the member's adaptations, its range of tolerance for physical and chemical conditions, its interactions with other components of the ecosystem, and its role in energy flow and matter recycling.
This is NOT the same as the organism's habitat.
The habitat is the physical location where a species lives.
The fundamental niche is the full potential range of conditions and resources a species could use.
Its realized niche is the part of the potential niche that allows a species to survive and avoid competition with other species for the same resources

14. Ecological Niches and Adaptation
Fig. 5-4 p. 91

15. Broad and Narrow Niches
Generalists
Some species have broad ecological roles and are termed generalist species.
Their living range is broad and includes many different places.
They can eat a variety of foods and tolerate a wide range of environments.
If the environment is changeable, the generalist will survive better than the specialist.
Specialists
Some species have narrow ecological roles and are termed specialist species.
Specialist species can live only in very specific environments.
This makes them more prone to extinction when environmental conditions change.
If the environment is constant, specialists have fewer competitors.
Intense competition may lead to evolutionary divergence of a single species into a variety of similar species with specialized niches.

16. Speciation: A new species arises when members of a population are isolated from other members so long that changes in their genetic makeup prevent them from producing fertile offspring if they get together again.
Fig. 5-7 p. 94

17. Speciation
Natural selection can lead to development of an entirely new species.
In speciation, two species arise from one when some members of a population cannot breed with other members to produce fertile offspring.
Allopatric Speciation is the most common mechanism and occurs in two phases:
Geographic isolation: physical separation for long time periods
Reproductive isolation: the gene pools are so changed that members become so different in genetic makeup that they cannot produce fertile offspring

18. Allopatric Speciation
Exactly how speciation occurs is not well understood. Most biologists believe in Allopatric (“other place”) Speciation: A small population becomes geographically isolated in some way.
Breeding only among themselves, its members evolve away from the ancestral
Humans and chimpanzees diverged, it is believe, because the ancestral species was divided by Africa’s Great Rift Valley

19. Sympatric Speciation
Sympatric Speciation is less common. It occurs when two species live close together but can't interbreed due to a mutation or subtle changes in behavior.
Sympatric speciation can involve seasonal or habitat isolation- potential mates aren’t in the same place at the same time- or behavioral isolation, for example when a courtship ritual develops that appeals to some but not all.
Northern Fence Lizard (Sceloporus undulatus hyacinthinus) male and female, showing sexual dimorphism.

20. Extinction
When population members cannot adapt to changing environmental conditions, the species becomes extinct.
A species manages to survive one to ten million years before extinction occurs.
Life has had to cope with many major natural disasters that may reduce or eliminate species.
Introduction of new species into an area has also led to reduction in number or elimination of species.
When local environmental conditions change, some species will disappear at a low rate; this is called background extinction.
Mass extinction is a significant rise in extinction rates above the background extinction level. Usually, from 25-70% of species are lost. Recent evidence suggests that there have been two mass extinctions on Earth. There appear to have been three mass depletions on Earth.
Mass depletions are periods of extinction are higher than normal , but not high enough to classify as a mass extinction

21. Mass Extinction
Adaptive radiations are recovery periods after mass extinction when numerous new species evolve to fill niches in changed environments. It takes one to ten million years to rebuild biological diversity after a mass extinction/depletion.
Terrestrial organisms
1600
Silurian
Devonian
Permian
Triassic
Jurassic
Cambrian
Ordovician
Cretaceous
Pre-cambrain
1200
Carboniferous
Marine organisms
Number of families
800
Tertiary
Quaternary
400
3500
545
500
440
410
355
290
250
205
145 65
1.8
Millions of years ago

22. Continental drift plays a role in speciation and extinction by isolating populations both geographically and reproductively
PANGAEA
LAURASIA
120°
80°
40°
80°
120°
120°
80°
80°
120°
GONDWANALAND
135 million years ago
225 million years ago
EURASIA
NORTH AMERICA
AFRICA
120°
80°
INDIA
120°
120° 0°
40°
120°
SOUTH
AMERICA
MADA-
GASCAR
AUSTRALIA
ANTARCTICA
65 million years ago
Present

23. Evolutionary tree models
The Tree of Life
Evolutionary tree diagrams interaction.
Gradualism vs. Punctuated Equilibrium

24. Human Impact on Extinction
The Earth's biodiversity is decreasing because of human activities.
Biodiversity equals speciation minus extinction.
Humans are causing the premature extinction of species, estimated to be 100 to 1,000 species per million species.
It has been predicted that by the end of the 21st century we may see the extinction of half of the present species now on Earth.
Humans and their activities are also destroying/degrading ecosystems that might be centers for future speciation.

25. What is the Future of Evolution?
Man has used artificial selection to change the genetic characteristics of populations.
We use selective breeding to obtain specific desired traits.
Traditional crossbreeding is a slow process; it takes many generations of selection for the desired trait.
Wild and cultivated roses illustrating artificial selection.

26. What is the Future of Evolution?
Genetic engineering/gene splicing are techniques that isolate, modify, multiply, and recombine genes from different organisms. Genes from different species that would never interbreed in nature are being transferred to each other.
Genetically modified organisms (GMOs)/transgenic organisms are the results of this gene splicing.
Gene splicing takes half as much time to develop a new crop/animal, as does traditional crossbreeding.
Cloning produces a genetically identical version of an individual.
Biopharming is a new field where genetically engineered animals act as biofactories to produce drugs, vaccines, antibodies, hormones, etc.

27. Phase 1 Phase 2 Make Modified Gene Make Transgenic Cell cell gene
Identify and extract
gene with desired trait
gene
Transfer plasmid
copies to a carrier
agrobacterium
A. tumefaciens
(agrobacterium)
DNA
Identify and remove
portion of DNA
with desired trait
plasmid
Agrobacterium
inserts foreign
DNA into plant
cell to yield
transgenic cell
Plant cell
Remove plasmid
from DNA of E. coli
Nucleus
E. coli
Host DNA
DNA
Foreign DNA
Insert extracted DNA
(step 2) into plasmid
(step3)
Genetically
modified
plasmid
Transfer plasmid
to surface
microscopic metal
particle
plasmid
Insert modified
plasmid into E. coli
Use gene gun
to inject DNA
into plant cell
Grow in tissue
culture to
make copies

28. Grow Genetically Engineered Plant
Phase 3
Grow Genetically Engineered Plant
Genetic engineering is an unpredictable process and raises privacy, ethical, legal, and environmental issues. It is a trial and error process.
The average success rate of genetic engineering experiments is about 1%.
There are many questions about gene therapy:
Who will be helped with genetic knowledge — only those who can pay for it?
If one has a defect, will he or she be able to get health insurance, or a job?
Should we clone spare parts for people's bodies?
Transgenic cell
from Phase 2
Cell division of
transgenic cells
Culture cells
to form plantlets
Transfer to soil
Transgenic plants
with new traits

29. What is the Future of Evolution?
Genetic Engineering
A backlash developed in the 1990s against increased use of genetically modified food plants and animals.
Proponents of more careful control of genetic engineering point out that most new technologies have had unintended, harmful consequences, so caution should be practiced regarding genetic engineering.
What is the Future of Evolution?
Humans have become such a powerful species so quickly due to two evolutionary adaptations: a complex brain and strong opposable thumbs.
Humans have quickly developed powerful technologies to meet our needs and wants.
Humans need to change our ways in order not to be called Homo ignoramus instead of Homo sapiens sapiens, the doubly wise.

30. Resources: