biodiversity and evolution chapter 4. the american alligator, worth saving?
TRANSCRIPT
Biodiversity and Evolution
Chapter 4
The American Alligator, worth saving?
Core Case Study: Why Should We Care about the American Alligator?
Largest reptile in North America
1930s: Hunters and poachers (sport, bellies, meat) • 90% killed off
1967: endangered species
1977: comeback, threatened species
Why are alligators important?
Keystone species
Presence in food web –Gar, eggs, small gators Gator holes- dug out, freshwater, drought Nesting mounds, used by other animals Pathways- keep waterways open, hold back
changes in swamp
Medicine: blood kills certain types of bacteria, antibodies that destroy drug resistant varieties
Four Scientific Principles of Sustainability
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.
What does biodiversity mean to you?
Natural Capital: Major Components of the Earth’s Biodiversity
Different types of diversity Species diversity: the number and abundance of
species present in different communities
Ecosystem diversity: The variety of ecosystems, aquatic environments found in a place or on earth
Functional diversity: variety in the processes and energy flow in an ecosystem: extra uses of nests, paths of gators
Genetic Diversity: Variety in traits, genetic material found within a certain species
Biodiversity Is a Crucial Part of the Earth’s Natural Capital
Vital renewable resources
Variety of food found in all ecosystems
Wood, fibers, energy, medicine
Waste and pest control
Air and water quality (regulation of ecosystem health
Questions on 4.1
Q2: What are three ways that the American alligator supports one or more of the four components of biodiversity within its environment?
Q3: What are three examples of how people, in their daily living, intentionally or unintentionally degrade each of these types of biodiversity?
Q4: What are the main differences between Functional and Ecological Diversity? What are the main differences between species and genetic diversity?
Q5: Why is having a lot of biodiversity on earth so beneficial to us?
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).
What does Evolution mean to you?
Do you think it happens?
Evidence?
What do these pictures have in common?
Biological Evolution by Natural Selection Explains How Life Changes over Time
Natural selection
Constant struggle for food, resources to survive
Some individuals have advantage over others
Those with tend to have more successful offspring
Charles Darwin • (gathered evidence AND published)
Alfred Russell Wallace
What is the tree of life?
Six Major Kingdoms of Species as a Result of Natural Selection
Fig. 4-3, p. 81
CenozoicMesozoic
Paleozoic
Precambrian
Mil
lio
ns
of
ye
ars
ag
oFirst humansExtinction of dinosaurs
Plantscolonize land
Origin ofmulticellularorganisms
Oldesteukaryotic fossils
Accumulation ofO2 in atmospherefrom photosyntheticcyanobacterium
Prokaryotes Eukaryotes
Origin of Earth
Earth cool enoughfor crust to solidify
Oldest prokaryoticfossils
AnimalsFungiPlantsProtistsArchaebacteriaEubacteria
0
500
4,500
4,000
3,500
3,000
2,500
2,000
1,500
1,000
Animation: Evolutionary tree of life
Animation: Evolutionary tree diagrams
The Fossil Record Tells Much of the Story of Evolution
Fossils• Physical evidence of ancient organisms• Bones, casts, tracks…• Some reveal what their internal structures
looked like, some their actions
How many species leave fossils? Have all fossils been discovered?
Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era
The Genetic Makeup of a Population Can Change
Populations evolve by becoming genetically different
Genetic variations• First step in biological evolution• Occurs through mutations in reproductive cells• Mutations in other cells can happen , but only
reproductive cell mutations are passed on• Sometimes a mutation can result in a new
genetic trait that gives it a better chance to survive, sometimes not.
Answer
Can a fish species willfully grow limbs and fingers if they are needed to crawl out of the water onto dry land?
Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
Natural selection: acts on individuals• Second step in biological evolution• Adaptation may lead to differential reproduction• Genetic resistance in bacteria, cockroaches
When environmental conditions change, populations• Adapt• Migrate• Become extinct
Fig. 4-5, p. 83
Most of the normal bacteria die
The genetically resistant bacteriastart multiplying
Eventually the resistant strainreplaces the strain affected bythe antibiotic
A group of bacteria, including genetically resistant ones, areexposed to an antibiotic
Normal bacterium
Resistant bacterium
Stepped Art
Humans and Natural Selection
• Is it still going on? Evidence
• Traits that might lead to differential production
• Do the number of offspring matter for human adaptation?
Case Study: How Did Humans Become Such a Powerful Species?
Three human adaptations• Strong opposable thumbs• Walk upright• Complex brain
Adaptation through Natural Selection Has Limits
Genetic change must precede change in the environmental conditions
Reproductive capacity • How many• How fast
Three Common Myths about Evolution through Natural Selection
“Survival of the fittest” is not “survival of the strongest”
Organisms do not develop traits out of need or want
No grand plan of nature for perfect adaptation
Questions on 4.2
Q1) Some people are born with 6 fingers or webbed toes. The above named features are examples of what biological concepts?
Q2) Do the features listed in Q1 have impact on the natural selection process of humans? Explain
Q3) Why does the tree of life have branches?
There is a grandeur to this view of life (evolution)
While this planet has gone cycling on…
Endless forms most beautiful and wonderful
have been and are beingevolved
Charles Darwin
Evolution Timeline Project/Lab
Video: Creation vs. evolution
Animation: Disruptive selection
Animation: Change in moth population
Animation: Stabilizing selection
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.
What drives evolution?
What determines the amount of resources?
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
Tectonic actions: Earthquakes, Volcanic eruptions can have profound effects on natural selection• Pollution• Change in ecosystem
Fig. 4-6, p. 85
225 million years ago 135 million years ago
65 million years ago Present
Stepped Art
Climate Change and Catastrophes Affect Natural Selection
Ice ages followed by warming temperatures
Demise of the giants (sloth, Saber tooth tigers)
Collisions between the earth and large asteroids • New species• Extinction
Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years
Science Focus: Earth Is Just Right for Life to Thrive
Certain temperature range (closeness to sun)
Dependence on water
Rotation on its axis (how fast or slow we spin)
Revolution around the sun (changes in season)
Enough gravitational mass (to hold on to the atmo)
Animation: Stanley Miller's experiment
Questions on 4.3
Q1) What is the connection between the environment and evolution?
Q2) Will humans evolve to a point where we can survive in space without a spacesuit or any protective device? Why or Why not?
Q3) how does pollution effect evolution?
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.
Evolution
Through geographic isolation• Groups of same species become physically
isolated• Migration, physical barriers (volcanoes to roads)
Through reproductive isolation• Mutation and change by natural selection occur in
isolated geographic populations long enough
• New species when interbreeding produces onlysterile offspring
Geographic Isolation Can Lead to Reproductive Isolation
Speciation
Two species arise from one
Environments change for 2 groups of same species
Change progresses to point where breeding produces sterile offspring
Animation: Speciation on an archipelago
Extinction is Forever
Extinction• Background 1:5,000,000• Mass >25%• 3-5 events in history with mass extinction and low
speciation
Endemic species • Specialized• Found in only one location• Particularly vulnerable
Golden Toad of Costa Rica, Extinct
Science Focus: Humans Have Two Ways to Change the Genetic Traits of Populations
Artificial selection
Genetic engineering, gene splicing
Consider• Ethics• Morals• Privacy issues• Harmful effects
Genetically Engineered Mice
Animation: Transferring genes into plants
Video: Cloned pooch
Exit questions
Q10 Distinguish between geographic isolation and reproductive isolation.
Q11 Distinguish between artificial selection and genetic engineering (gene splicing)
Q12 Distinguish between background extinction and mass extinction?
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.
Evolution
Through geographic isolation• Groups of same species become physically
isolated• Migration, physical barriers (volcanoes to roads)
Through reproductive isolation• Mutation and change by natural selection occur in
isolated geographic populations long enough
• New species when interbreeding produces onlysterile offspring
Species Diversity: Variety, Abundance of Species in a Particular Place
Species diversity• Species richness (diversity in species)• Species evenness (abundance of each
species)
Diversity varies with geographical location• Most species-rich communities• Tropical rain forests• Coral reefs• Ocean bottom zone• Large tropical lakes
Variations in Species Richness
Variation in species evenness
Temperate Forest, African Savannah, Canadian Aspen forest
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
Larger and closer is more species rich
“Island” isolated region
Species-Rich Ecosystems Tend to Be Productive and Sustainable
Species richness seems to increase productivity and stability or sustainability of a location
More diverse ecosystem, more productive, greater biomass
More diverse, more complex web, more resistant to environmental disturbances
Only a hypothesis, more study is needed
Questions on 4.5
Q15) Distinguish between species richness and evenness
Q16) Suppose we have 2 national parks close to each other surrounded by development. One is a large park and the other much smaller. Which park is likely to have the highest species richness? Why?
Q17) Explain why species rich ecosystems tend to be productive and sustainable
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.
Each Species Plays a Unique Role in Its Ecosystem
Ecological niche• Pattern of living, species way of life and includes
everything that affects survival and reproduction
Generalist species (mice, humans, raccoons)• Broad niche
Specialist species
(Tiger salamanders, pandas)• Narrow niche
Specialist Species and Generalist Species Niches
Case Study: Cockroaches: Nature’s Ultimate Survivors
Cockroaches• Generalists• High reproductive rates• 10 million annually
• Eat almost anything:• Finger nail clippings,
electric cords, soap• Live and breed in all but
arctic environ• Antennae, knee joints, eyes• Sample food-avoid poison
Good: food for higher order consumers
Fig. 4-13, p. 93
Black skimmerseizes small fishat water surfaceBlack skimmerseizes small fishat water surface
Brown pelican divesfor fish, which itlocates from the air
Avocet sweeps billthrough mud andsurface water in searchof small crustaceans,insects, and seeds
Dowitcher probesdeeply into mud insearch of snails,marine worms, andsmall crustaceans Herring gull
is a tirelessscavenger
Ruddy turnstonesearches undershells and pebblesfor smallinvertebrates
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 wormsand small crustaceansleft by receding tide
Piping plover feeds on insects and tinycrustaceans on sandy beaches
Specialized Feeding Niches of Various Bird Species in a Coastal Wetland
Niches Can Be Occupied by Native and Nonnative Species
Native species
Nonnative species; invasive, alien, or exotic species• May spread rapidly• Not all are villains (farm- commercial animals)• All disturb the existing ecosystem
Killer Bees
1957, Brazil to increase honey production
Instead killed off native bee population
Been migrating North every since
Not terror movie life, but more aggressive and unpredictable
Indicator Species Serve as Biological Smoke Alarms
Indicator species• Can monitor environmental quality • Trout (need clean highly oxygenated water)• Birds (fragmentation, pesticides)• Butterflies (fragmentation, species loss)• Frogs (next slide)
Case Study: Why Are Amphibians Vanishing? (1)
Habitat loss and fragmentation
Prolonged drought
Pollution
Increase in UV radiation
Parasites (worms causing increase in birth defects)
Viral and fungal diseases
Climate change (2005 and 2008 studies)
Overhunting (Asia and France)
Nonnative predators and competitors
Case Study: Why Are Amphibians Vanishing? (2)
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
Fig. 4-14, p. 94
Sexualreproduction
Adult frog(3 years) Young frog
Tadpole developsinto frog
Tadpole
Egg hatches
Organ formation
Fertilized eggdevelopment
Eggs
Sperm
Life Cycle of a Frog
What is a keystone?
Keystone, Foundation Species Determine Structure, Function of Their Ecosystems
Keystone species • Pollinators• Top predator• Loss of keystone species lead to population
crashes of other species in ecosystem
Foundation species• Create or enhance their habitats, which benefit
others • Elephants (trails) • Beavers (build wetlands)
Keystone and foundation species play similar role in building and
maintaining an healthy ecosystem
Why should we protect sharks?
Case Study: Why Should We Protect Sharks?
Keystone species• Eat dead and dying fish in the ocean• Control other populations• Strong immune systems • Wounds do not get infected• Almost never get cancer• Could help humans if we understood their immune
system
4.6
Q20) Distinguish between native, invasive, indicator, keystone and foundation species
Q21) Distinguish between specialist species and generalist species.
Writing assignment
Critical thinking questions 7, 8 on pg 98
Use ideas discussed in this or other chapters to fortify your answer to the questions
UN Project Questions
1. Are there regions of your country with large amounts of biodiversity?
2. What climate conditions/Geologic features have influence natural selection in the major biomes of your country
3. Indicate some unique indicator, keystone, foundation, invasive and specialist species that live within the borders of your country
4. Does the people in your country get most of their food from within ?