b205ch19

Please do Online Course Evaluations This Week
Ch 19: Communities & Ecosystems (definitions). sign up to be an activist, Ch 18/19 ppt.

A. Biology & Society: Reefs: Coral & Artificial, fig 1, a community & an ecosystem

B. The Four Key Properties of Communities: Biodiversity & Conservation

1) Biodiversity (easy index): # of species / # of organisms, simpler is # of species
Desirable: many species & none dominant, fig. 2 & 3, prairie near here

Complex index &

field exercise: diversity rises with /\ species richness & /\ evenness.

Aug. 2002: 24 hr. Calumet Bioblitz: > 2,200 species

2) Prevalent form of vegetation: fig. 2: savanna, determines the kinds of animals:
e.g. conifer, mixed or deciduous forest, or grassland, etc

vertical stratification is greatest in forest, increases diversity, scroll,
also true underwater (Monterey Bay, CA)

3) Stability: #5: resistance to change, & able to recover, high diversity > high stability.
Forests are stable but slow to recover from disturbance, prairie recovers fast from fire
4) Trophic structure: fig. 4, 1) Producers, & 2) various levels of consumers, including detritivores

CHECKPOINT p 408
1. How can a community have many species, but low diversity?
2. Word used to indicate feeding level in a community

C. Interspecific Interactions = between different species, in Communities

Competition between species, for food, nesting sites, etc., limits each poulation,
so, through natural selection, adaptations reduce competition: competitive exclusion principle, fig 5 & 6
Aslo called resource partitioning: Darwins's finches or lizards, fig 7. Else one species may/will go extinct
Ecological niche - all the biotic & abiotic resources in one species' environment
Is probably unique for every species.
Fundamental niche is (scroll) larger than realized niche, examples
Predation: includes herbivory: plant defenses against herbivory:

pharmacy's origins (slide 2)

Predator adaptations include acute senses (community ecology .ppt), an activity,
Aslo, claws, teeth, fangs, stingers, poison, camouflage etc
Animal defenses against predators: flee, & fig. 8, 9, & cryptic fig 10, or warning coloration fig 11.
Batesian mimicry, fig. 12, harmless moth larva resembles a snake!
Müllerian mimicry, fig. 13, two unpalatable species resemble each other, good
Predation maintains species diversity, fig 14, no single species gets too abundant:
Wolves in Yellowstone was done for this reason
Keystone species (Ex 13.1) maintain diversity: wiki, not always top predator, lesson,
sea otter in detail
Symbiotic Relationships: means physical interaction between species
parasitic fig. 15, one benefits at others expense: human diseases, coevolution occurs
mutualistic, fig. 16, both benefit like clownfish/sea anenome
commensalism, only one benefits: spider webs on trees!
The Complexity of Community Networks (food webs are below)
In ecosystems several species frequently interact:
fig 17: a caterpillar eats a plant which releases chemicals to attract a wasp which lays its eggs in the caterpillar

CHECKPOINT p 414
1. Testing: competitive exclusion, fig 6, slide 18, or is it susceptibility to drying out that keeps species separate?
1a. How can you determine the fundamental niche of a species, as against the realized niche
2. A ? species helps maintain diversity in a community
3. Bacteria in the large intestine make vitamin K, which we absorb: which type of symbiosis?

D. Disturbances of Communities & Recovery

Stability and balance are not characteristic of most communities
Disturbances happen: earthquakes, storms, fires, floods, drought, human interventions, global warming
fire ecology, includes using fire as a tool
Disturbances lead to Ecological Succession: either primary or secondary
Primary is from bare rock/sand etc, fig. 18, IN Dunes,
Secondary is after a disturbance - could be NIPSCo killing a tree
Small organisms begin process > replaced by or added to > larger & more diverse until reach climax

Dunes Succession Trail

, NPS fire management.,

IDNL..

A Dynamic View of Community Succession:
Small scale disturbances enable greater diversity than no disturbance,
because organisms differ at each stage of succession
So disturbances like fig 19 - a tree falls - create greater diversity than none or total.
Prairies need fire else woody plants = shrubs grow & succession follows > no prairie.
A prairie fire is not a major disturbance, why?, but a forest fire is (like deforestation), why?

CHECKPOINT p 416
1. What is the major abiotic! difference between primary & secondary succession?
2. Why don't trees come first in primary succession?
Can trees come first in secondary succession?

Do rest on Friday, lab books due on Friday
E. An Overview of Ecosystem Dynamics

Ecosystems include communities of organisms, & the physical environment:
artificial biosphere was not in balance
Fig 20: @ PWL El Ed students set up a biosphere in aquaria: (205/206 has own room)

Trophic Levels & Food chains:
Fig 21 Producers at the base, then primary, secondary, tertiary, quaternary level, consumers,
detritovores / river food chain or web? (one example), earthworm in soil, fungi fig 22
Food webs like fig 23, are more realistic, than chains, Great Lakes, like fig 23.
Fig 24: most productive ecosystems: algal beds, coral reefs, tropical rain forests & estuaries
So for better or worse, these are best choices for biofuels, not cornbelt
Algal bed as biofuel, world primary productivity, ecosystem productivity in Europe
Energy flows through ecosystems but chemicals recycle (below), fig 20, Serengeti
Energy is ultimately lost into space as heat
Chemicals started in rocks, air, water, oceans as earth cooled
Fig 25: only about 10% of the biomass/energy an organism consumes makes growth:

So energy pyramids have only 3/4/5 levels, fig 26, estuary, .

It takes ~ the same photosynthetic productivity to produce 10 kg. of corn or 1 kg. of beef, fig 27
So vegetarianism conserves food, resources, & the environment (in textbook)

CHECKPOINT p 422
1. In shrubland ecosystem which has greates biomass?: all the insects, or all the birds eating them?
2. Why is a pound of bacon so much more expensive than a pound of corn?

F. Chemical Cycling in Ecosystems

The General Scheme of Chemical Cycling, fig 28, wiki
1) Each cycle: chemical has an abiotic reservoir
2) Each cycle: chemical enters organisms:
3) Each cycle: chemical leaves organisms:
Water, phosphorous & carbon, nitrogen

CHEMICAL Fig 29	ABIOTIC RESERVOIR	ENTERS BIOTIC	LEAVES BIOTIC	COMMENTS
Carbon wiki	atmosphere carbon dioxide	producers: photosynthesis	all organisms: respiration	not in balance: fossil fuels & deforestation
Nitrogen (wiki)	Atmosphere Nitrogen	nitrogen fixing bacteria in soil	denitrifying bacteria in soil	fast biotic cycle = food chain + soil
Phosphorous (never in atmosphere)	in rocks & in water - phosphate	producers roots	decomposition	slow abiotic cycle alone, fast biotic cycle + soil
Water, wiki, largest arrow?	Oceans, lakes, ice, groundwater	producers roots, consumers food	transpiration, excretion, & decomposition	abiotic cycle: evaporation & precipitation

CHECKPOINT
1. Main abiotic reservoir for carbon?
2. What happens to carbon if detritivores all quit?
3. Fast phosphorous cycling is more localized than the others' cycles, why? (answer is also true for nitrogen!)
4. Globally most water moves from ? to ?
5. What happens if the producers have not enough organisms eating them?, answer 1, answer 2

REVIEW FOR TEST: MUST COME BY 9 AM
Ch 27
Trace the pathway of a REACTION =
               hitting the brakes in response to green light changing to red, or hearing a baby cry
Ch 18 p 404
1) design experiment to find out how temperature affects the growth of phytoplankton (what are they?)
2) mark & recapture > a population of mice = 350. But the traps were baited with food. Is the 350 too high or too low?
Ch 19 p 438
1) two identical small plots in a desert, with various plants, & each has same five species of wildflowers
    fence one plot to keep out kangaroo rats (herbivore) > after two years only 1 species remains
    unfenced plot still has all five. What happened?
2) Biosphere 3 is yours to design, what species do you put in it?

STOP, REST IS NOT ON TEST 4

G. Terrestrial Biomes: Low temperature &/or low rainfall biomes are fragile: Anza-Borrego (click photos).

Define the term biome, and describe the two (temperature & rainfall)/(scroll to pyramid) climate traits that determine the biome type, fig. 30-34. Also explain how biomes get their names: major physical or climactic features or predominant vegetation. Textbook: tundra, coniferous forest, temperate deciduous forest, temperate grassland, chaparral, desert, savanna, tropical forest.

H. Aquatic Biomes (most of biosphere): Freshwater types: 16 & 17, Marine types: 18.

Ponds/lakes: Compare photic, aphotic, & benthic zones, fig. 35a & 38, algae, images, aquatic plants, plankton - scroll, scroll, exercise. Distinguish between benthos & detritus, & between oligotrophic, mesotrophic & eutrophic
Streams/rivers: Compare the properties of a stream or river at its source, wetlands, midriver, & where it empties into a lake or the sea. Explain how human activities impact the properties of rivers and streams, fig. 36 & 37.
Compare characteristics of estuaries, more, Chesapeake, map, 2, intertidal zones, fig. 39, marine pelagic zones, organisms, fig. 38, & coral reefs (scroll for world map). Ocean..Antartic..good. Explain what is special (no sunlight, so no photosynthesis) about hydrothermal vent communities, fig. 40, so chemosynthesis instead of photosynthesis).

I. Evolution Connection: Coevolution in Biological Communities

Describe the adaptations of the passionflower Passiflora and the butterfly Heliconius that have resulted from their coevolution, fig. 41, more examples..local example: Karner Blue butterfly on Lupine..butterfly..