1. Evolution and Biodiversity

2. Has led to the variety of species we find on Earth today
Biological Evolution
Has led to the variety of species we find on Earth today

3. 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

4. Natural Selection
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.

5. Zebra mussels on native mussel
Three conditions are necessary for biological evolution by natural selection
Genetic variability, traits must be heritable, trait must lead to differential reproduction
Zebra mussels on native mussel

6. Adaptation
An adaptive trait is any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions

7. Flying fish
Loach
Fish Adaptations
Sun fish
Tri-pod fish

8. 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

9. The Japanese hornet feeds on Japanese honeybees
Japanese honeybees defend their nests and their young by surrounding the Japanese hornet and fluttering their wings increasing the body temperature of the hornet and exposing the hornet to increased carbon dioxide levels

10. 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.
Gestation period is 22 months for an elephant

11. 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.

12. 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.

13. 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
Fig. 4-5, p. 88

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

15. 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.
Meteor Crater, Arizona

16. 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.

17. Geographic Isolation
…can lead to reproductive isolation, divergence of gene pools and speciation.
Figure 4-10

18. 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.

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

20. 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)
Fig. 4-8, pp

21. Evolutionary Divergence
Each species has a beak specialized to take advantage of certain types of food resource.
Figure 4-9

22. Ecological Roles Generalist species Specialist species Broad niche
Live in many different areas
Eat variety of foods
Tolerate wide range environmental conditions
Narrow niche
May only live in one type of habitat
Few types of food
Tolerate narrow range of environmental conditions

23. 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

24. 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

25. 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

26. 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

27. Using biotechnology to develop blight-resistant American Chestnut
Before 1900 the American Chestnut made up 25% of the standing trees in the Appalachian forest
These trees grew to 100 ft rapidly and their trunks were more than 6 ft in diameter
The chestnut blight was introduced into the U.S. and now the tree rarely reaches 30 ft before dying
Scientists have created transgenic American Chestnut resistant to the chestnut blight

28. six-pack abs = more muscle mass which is more profit
Transgenic trout with
six-pack abs = more muscle mass which is more profit
Transgenic fish which glow were originally developed to detect pollution – but developers can make more money in the aquarium trade

29. 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?

31. 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).

32. The End