1. Biodiversity and Evolution
Chapter 4

2. Core Case Study: Why Should We Care about the American Alligator?
Largest reptile in North America
1930s: Hunters and poachers
Importance of gator holes and nesting mounds
1967: endangered species
1977: comeback, threatened species

3. Alligator’s niche
Fish, insects, snakes, turtles, birds, etc. live in gator holes during dry weather
Old gator nests are used for nesting and feeding sites for herons, egrets, red-bellied turtles
Alligators eat gar (fish that eats game fish - bass and bream)
Alligators move around and keep open water available and free of vegetation.
Keystone species

5. 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.
The more biodiverse a place is, the more likely its life is to survive changes.  Most important thing you’ll see all semester.

6. Biodiversity Is a Crucial Part of the Earth’s Natural Capital
Vital renewable resource
Species diversity – number and abundance of species
Ecosystem diversity – variety of ecosystems available
Functional diversity – variety of bio and chem processes in ecosystems
Genetic diversity – variety of genes and alleles among all species (alleles are versions of genes, remember?)

7. Natural Capital: Major Components of the Earth’s Biodiversity

8. Evolution pop quiz
Don’t worry, you’ll get an A.

9. Some student comments about evolution:
“I think it is interesting.”
“I believe that God made the world to adapt to it’s surroundings.”
“It takes a lot of words to get the whole thought.”
“It is based in solid science. I do not believe that religion and evolution are mutually exclusive, as I am both religious and supportive of evolution.”
“I was raised religiously so evolution is practically a swear word in my house. However, I really enjoy learning about it because it makes sense to me that things change and adapt over time.”

10. More student comments:
“I think that evolution happens to a point but I don’t agree that humans evolved from nothing.”
“I don’t like some parts of the study of evolution like people saying we evolved from apes because we didn’t.”
“I have a hard time believing we came from monkeys.”
“It is interesting, but I don’t believe it. I believe God created all animals and plants.”
“I don’t necessarily believe this is how life happened. There have been many ideas contrary to the study.”
“It doesn’t answer all of the questions about how the world came about.”

11. 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).

12. Biological Evolution by Natural Selection Explains How Life Changes over Time
Natural selection- (watch on your own time, if you’re interested in who Darwin was.)
Charles Darwin
Alfred Russel Wallace
Tree of Life
(By the way, what’s a theory, again??)

13. Six Major Kingdoms of Species
Prokaryotes
Eukaryotes
Eubacteria
Archaebacteria
Protists
Plants
Fungi
Animals
Cenozoic
First humans
Mesozoic
Extinction of dinosaurs
Plants
colonize land
Paleozoic
500
Origin of
multicellular
organisms
1,000
1,500
Oldest
eukaryotic fossils
2,000
Six Major Kingdoms of Species
Millions of years ago
Accumulation of
O2 in atmosphere
from photosynthetic
cyanobacterium
2,500
Precambrian
Figure 4.3
Overview of the evolution of life on the earth into six major kingdoms of species as a result of natural selection. For more details, see p. S46 in Supplement 7.
3,000
Click here!
3,500
Oldest prokaryotic
fossils
4,000
Earth cool enough
for crust to solidify
4,500
Origin of Earth
Fig. 4-3, p. 81

14. The Fossil Record Tells Much of the Story of Evolution
Fossils
Physical evidence of ancient organisms
Reveal what their internal structures looked like
Fossil record is incomplete: why?

15. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

16. Lots of evo this summer: read and watch videos.
What can you learn from fossils, really?
What about dinosaur fossils?
Evolution driven by geographic isolation in the Ice Age:
Evolution of really weird trees:

17. The Genetic Makeup of Population Can Change
Populations evolve by becoming genetically different
Genetic variations
In a population, there is variation among individuals
Occurs through mutations in reproductive cells

18. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Natural selection: acts on individuals
Individuals with traits that are beneficial to the conditions are more likely to survive and reproduce (differential reproduction)
Over time there is a shift in the most common traits, such that beneficial traits become more common within the population (Populations evolve, individuals don’t!)
Genetic resistance – good example
When environmental conditions change, populations must:
Adapt – have traits which allow survival in new conditions
Migrate – move somewhere where conditions are better
Or…become extinct

19. Evolution by Natural Selection
A group of bacteria, including genetically resistant ones, are
exposed to an antibiotic
Normal bacterium
Resistant bacterium
Eventually the resistant strain
replaces the strain affected by
the antibiotic
The genetically resistant bacteria
start multiplying
Most of the normal bacteria die
Figure 4.5
Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria.
Stepped Art
Fig. 4-5, p. 83

20. Case Study: How Did Humans Become Such a Powerful Species?
Three human adaptations
Strong opposable thumbs
Walk upright
Complex brain

21. Adaptation through Natural Selection Has Limits
Genetic change must precede change in the environmental conditions. The alleles that are beneficial in the new environmental conditions must already be found within the population before the conditions change.
(Populations don’t suddenly sprout new traits as a result of environmental changes.)
Reproductive capacity – populations with high genetic diversity and fast reproduction rates are most able to adapt to changes (mosquitos, weeds, rats, bacteria, etc.)

22. Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest”
Fittest = better adapted to the ENVIRONMENT
Traits that confer “fitness” in one biome may be detrimental in another
(gills are great for aquatic biomes, but useless in deserts!)
Organisms do not develop traits out of need or want
There is no grand plan in nature for “perfect” adaptation
Don’t assume all species are headed in a specific evolutionary direction!

23. Five Fingers of Evolution

24. 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.

25. Geologic Processes Affect Natural Selection
Tectonic plates affect evolution and the location of life on earth
Location of continents and oceans
Species physically move, or adapt, or form new species through natural selection
Earthquakes – fissures can isolate species and cause speciation (geographic isolation)
Volcanic eruptions – destroy habitats

26. Movement of the Earth’s Continents over Millions of Years

27. Climate Change and Catastrophes Affect Natural Selection
Ice ages followed by warming temperatures
Collisions between the earth and large asteroids
Extinction
New ecological roles become available for species that don’t become extinct
Go back a slide – when did dinosaurs become extinct? Why? If you’re interested in how we know, read T. Rex and the Crater of Doom!

28. Changes in Ice Coverage in the N. Hemisphere during the last 18,000 Yrs

29. Science Focus: Earth Is Just Right for Life to Thrive
Certain temperature range H2O = s, l, AND g!!
Dependence on water
Rotation on its axis – no “dark side/bright side” temp issues
Revolution around the sun – not too close or too far
Enough gravitational mass to keep atmosphere
(why? Well, where else could humans evolve?)

30. 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.

31. How Do New Species Evolve?
Geographic isolation
Reproductive isolation

32. Geographic Isolation Can Lead to Reproductive Isolation

33. Extinction is Forever Extinction
Endemic species – species found in only one area, such as on islands
Particularly vulnerable – difficult to migrate when changes occur

34. Extinction Can Affect One Species or Many Species at a Time
Background extinction – happens all the time through out history
Mass extinction – significant rise above background rate
Has happened five times (about once per million years). Why? We’re not sure.
250mya 95% of all species became extinct!
(OK maybe only 3 times – debated … should we define mass extinction by many species going extinct plus low speciation rate?)
Extinctions will happen, but do we have a responsibility to make sure we aren’t causing premature extinctions?

35. Science Focus: We Have 2 Ways to Change the Genetic Traits of Populations
Artificial selection – we’ve been doing this since the dawn of agriculture.
Genetic engineering, gene splicing
Consider
Ethics
Morals
Privacy issues
Harmful effects

36. 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.

37. Species Diversity: Variety, Abundance of Species in a Particular Place
Species richness -
Species evenness -
Diversity varies with geographical location
Most species-rich communities
Tropical rain forests
Coral reefs
Ocean bottom zone
Large tropical lakes

38. Science Focus: Species Richness on Islands
Species equilibrium model, theory of island biogeography
Rate of new species immigrating should balance with the rate of species extinction
Island size and distance from the mainland need to be considered

39. Species-Rich Ecosystems Tend to Be Productive and Sustainable
Species richness seems to increase productivity and stability or sustainability
How much species richness is needed is debatable

40. 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.

41. Each Species Plays a Unique Role in Its Ecosystem
Ecological niche, niche
Pattern of living – how much space? Water? Sunlight? Temp range? What food source?
Generalist species
Broad niche
Specialist species
Narrow niche

42. Specialist Species and Generalist Species Niches

43. Case Study: Cockroaches: Nature’s Ultimate Survivors
Generalists
High reproductive rates
Giant panda and tiger salamanders
Specialists
Low reproductive rates
When (where) would being a specialist be advantageous?

44. Specialized Feeding Niches of Various Bird Species in a Coastal Wetland
Ruddy turnstone
searches under
shells and pebbles
for small
invertebrates
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Black skimmer
seizes small fish
at water surface
Brown pelican dives
for fish, which it
locates from the air
Herring gull
is a tireless
scavenger
Avocet sweeps bill
through mud and
surface water in search
of small crustaceans,
insects, and seeds
Flamingo feeds on minute organisms in mud
Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation
Louisiana heron wades into water to seize small fish
Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Piping plover feeds on insects and tiny
crustaceans on sandy beaches
Figure 4.13
Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources.
Fig. 4-13, p. 93

45. Niches Can Be Occupied by Native and Nonnative Species
Nonnative species; invasive, alien, or exotic species
May spread rapidly – (or may not be able to survive in the new conditions)
Not all are villains, but many that are successful in the new habitat outcompete natives.

46. Indicator Species Serve as Biological Smoke Alarms
Can monitor environmental quality
Trout
Birds
Butterflies
Frogs

47. Case Study: Why Are Amphibians Vanishing?
Habitat loss and fragmentation
Prolonged drought
Pollution
Increase in UV radiation
Parasites
Viral and fungal diseases
Climate change
Overhunting
Nonnative predators and competitors

48. Case Study: Why Are Amphibians Vanishing?
Importance of amphibians
Sensitive biological indicators of environmental changes
Adult amphibians
Important ecological roles in biological communities
Genetic storehouse of pharmaceutical products waiting to be discovered

49. Life Cycle of a Frog Adult frog (3 years) Young frog Sperm
Tadpole develops
into frog
Sexual
reproduction
Tadpole
Figure 4.14
Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors.
Eggs
Fertilized egg
development
Egg hatches
Organ formation
Fig. 4-14, p. 94

50. Keystone, Foundation Species Determine Structure, Function of Their Ecosystems
Keystone species
Pollinators
Top predator
Foundation species
Create or enhance their habitats, which benefit others
Elephants
Beavers

51. Case Study: Why Should We Protect Sharks?
Keystone species
Eat dead and dying fish in the ocean
Strong immune systems
Wounds do not get infected
Almost never get cancer
Could help humans if we understood their immune system
For every shark that injures a person, we kill 1 million sharks.