1. Biodiversity and Evolution
Chapter 4

2. 4-1 What Is Biodiversity and Why Is It Important?
Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.

3. Major Components of the Earth’s Biodiversity

4. Why Should We Care About Biodiversity?
Biodiversity provides us with:
Natural Resources
food water, wood, energy,
and medicines
Natural Services
air and water purification, soil fertility, waste disposal, pest control
Aesthetic pleasure

5. 4-2 Where Do Species Come From?
Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations.
Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

6. 4-2 Where Do Species Come From?
Biological evolution by natural selection involves the change in a population’s genetic makeup through successive generations.
Natural selection – some individuals in a population has genetically based traits that enhance their ability to survive and produce offspring.
This has led to the variety of
species we find on the earth today.

7. The Fossil Record Tells Much of the Story of Evolution
Our knowledge about past life comes from fossils, chemical analysis, cores drilled out of buried ice, and DNA analysis.
Fossil record – the cumulative body of fossils we have found to date
Fossil record is uneven and incomplete
Some life left no fossils
Other fossils decomposed
Still others not found yet
There is more evidence to support evolution than any other scientific theory…including the Law of Gravity!!

8. The Genetic Makeup of a Population Can Change
Populations – not individuals – evolve by becoming genetically different.
Genetic variability: organisms in a population have slightly different genes
Mutations: random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring

9. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Natural selection: acts on individuals
Adaption – any heritable trait that enables an individual to survive and reproduce better under prevailing environmental conditions
Adaptations may lead to differential reproduction
Certain individuals leave behind MORE offspring than other less adapted individuals

10. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Summary: genes mutate, individuals are selected, populations evolve that are better adapted to survive and reproduce under existing environmental conditions.
When environmental conditions change, populations: adapt, migrate, or become extinct.

11. Case Study: How Did Humans Become Such a Powerful Species?
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)
Social skills and communication

12. Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest”
Fitness means ability leave behind offspring, not physical or athletic fitness
Organisms do not develop traits out of need or want
A giraffe did not get a longer neck because it wanted it
Those with too short of a neck starved and those with longer necks got enough food to reproduce frequently
No grand plan of nature for perfect adaptation
There is not ultimate goal of perfection, just populations reacting to the current environmental conditions, whatever they may be…

13. 4-3 How Do Geological Processes and Climate Change Affect Evolution?
Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

14. 4-3 How Do Geological Processes and Climate Change Affect Evolution?
Movement of tectonic plates
Location of continents and oceans
Earthquakes
Volcanic eruptions
Ice ages followed by warming temperatures
Collisions between the earth and large asteroids
These processes can wipe out existing species and/or help form new ones
Species physically move, or adapt, or form new species through natural selection

15. 4-3 How Do Geological Processes and Climate Change Affect Evolution?
Continents and oceanic basins locations influence climate.
The movement of continents have allowed species to move, or have kept them isolated.

16. 4-3 How Do Geological Processes and Climate Change Affect Evolution?
Changes in climate throughout the earth’s history have shifted where plants and animals can live.
Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years

17. Science Focus: Earth Is Just Right for Life to Thrive
4-3 How Do Geological Processes and Climate Change Affect Evolution?
Science Focus: Earth Is Just Right for Life to Thrive
Certain temperature range
Right distance from the Sun
Dependence on water
Rotation on its axis
Revolution around the sun
Enough gravitational mass

18. 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity.
Concept 4-4B Human activities can decrease biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

19. How Do New Species Evolve?
Reproductive Isolation - divergence of gene pools and speciation as a result of being separated in some way:
Geographic isolation
Behavioral isolation
Temporal isolation
Speciation: A new species can arise when members of a population become isolated for a long period of time.

20. How Do New Species Evolve?
Isolation can lead to changes in genetic makeup, preventing them from producing fertile offspring with the original population if reunited.

21. Extinction Is Forever
Extinction occurs when the population cannot adapt to changing environmental conditions – whether natural or man-made.
Endemic Species – species found in only one specific area – are especially vulnerable to extinction.
The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate.

22. Extinction Can Affect One Species or Many Species at a Time
Background Extinction – a very small amount of organisms go extinct as ecological conditions change ( % annually)
Mass Extinction – extremely high extinction rate as a result of a catastrophic global event (25-75%)
Extinction events are bad for some organisms but can be an opportunity for others.

23. Extinction Can Affect One Species or Many Species at a Time

24. Science Focus: We Have Two Ways to Change the Genetic Traits of Populations
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.

25. 4-5 What Is Species Diversity and Why Is It Important?
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

26. 4-5 What Is Species Diversity and Why Is It Important?
Species Diversity: the number of different species it contains (species richness) combined with the abundance of individuals within each of those species (species evenness).
Species diversity is highest in the tropics and declines as we move from the equator toward the poles.
Most species-rich communities:
Tropical rain forests
Coral reefs
Ocean bottom zone
Large tropical lakes

27. 4-5 What Is Species Diversity and Why Is It Important?
Species richness seems to increase productivity and stability/sustainability of an ecosystem
Greater richness means a greater ability to withstand and rebound from environmental disturbances or catastrophe.
Drought
Disease
Invasive species

28. 4-6 What Roles Do Species Play in Ecosystems?
Concept 4-6A Each species plays a specific ecological role called its niche.
Concept 4-6B Any given species may play one or more of five important roles – native, nonnative, indicator, keystone, or foundation roles – in a particular ecosystem.

29. Each Species Play s a Unique Role In It’s Ecosystem
Each species in an ecosystem has a specific role or way of life (niche or ecological niche).
Fundamental niche: the full potential range of physical, chemical, and biological conditions and resources a species could theoretically use.
Realized niche: to survive or to avoid competition, a species usually occupies only part of its fundamental niche.

30. Each Species Play s a Unique Role In It’s Ecosystem
Specialized Feeding Niches of Various Bird Species in a Coastal Wetland

31. Each Species Play s a Unique Role In It’s Ecosystem
Generalist species tolerate a wide range of conditions.
Specialist species can only tolerate a narrow range of conditions.

32. 4-6 What Roles Do Species Play in Ecosystems?
Native, nonnative, indicator, keystone, and foundation species play different ecological roles in communities.
Native species: those that normally live and thrive in a particular community.
Nonnative species: those that migrate, deliberately or accidentally introduced into a community.
AKA: invasive, alien, or exotic species

33. Indicator Species Serve as Biological Smoke Alarms
Indicator Species – ones that serve as early warnings of damage to a community or an ecosystem.
Trout species because they are sensitive to temperature and oxygen levels.
Lichens (symbiosis of a fungus and algea) because they are sensitive to air quality – especially sulfer dioxides.

34. 4-6 What Roles Do Species Play in Ecosystems?
Keystone species help determine the types and numbers of other species in a community thereby helping to sustain it.
Elimination of the keystone species, drastically alters the structure of the community.

35. 4-6 What Roles Do Species Play in Ecosystems?
Expansion of keystone species category:
The community would still function without the foundation species, but its presence enhances the community in ways that benefit many other species.
Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize.

36. Sea Otters: A Classic Keystone Species
European and Russian trappers hunted sea otters to near extinction in the 18th and 19th centuries.
The decline of the sea otters, which are essential to keeping sea urchins in check, allows sea urchin populations to explode.
The sea urchins decimate the kelp population, which are critical habitat for spawning fish.
Fish begin to decline for lack of spawning habitat; this affects fishermen's catches.
Finally, an international treaty is enacted to protect sea otters.
In areas where the otters recovered, urchin populations are once again kept down, the kelp beds recover, fish nurseries recover, and fish catches rise again.