1. Unit 4: Pt. 1 Community Ecology
AP Environmental Science

2. Species diversity Species richness – number of different species
Species evenness – abundance of individuals within each of those species

3. Habitat fragmentation causes significant decline in species diversity
Reduce species richness
Reduce amount of functional habitat
Cause isolation of a species
Possibility of genetic drift or inbreeding

4. Edge Effects Associated with Habitat Fragmentation Can Reduce Biodiversity
Makes many species vulnerable to stresses such as predators and fires
Creates barriers that can prevent some species from colonizing new areas and finding food and mates

5. Edge effect

6. Conservation Biologists Protect Biodiversity
Preserving large areas of habitat
Using migration corridors to link smaller habitat patches

7. Bridges over roads
Tunnels under roads

8. Who benefits from wildlife corridors?

9. The Most Species-rich Environments
Tropical forests
Coral reefs
Deep sea
Large tropical lakes

10. Three Major Factors Affect Species Diversity
Latitude (distance from equator)
Depth (aquatic systems)
Pollution (aquatic systems)

11. Number of Species Found on an Island Determined by a Balance Between:
Rate at which new species immigrate to the island
The rate at which species become extinct on the island

12. Two features of an island which affects its immigration and extinction rate
Island’s size
Island’s distance from the mainland

13. Canary Archipelago
What can you predict about how each island was colonized by wild species?

14. General principles of island colonization
The closer the island is to another land mass, the higher the probability of colonization.
2) The older the island, the more likely it will be colonized.
3) The larger the island, the more species are likely to be established.
4) The geographic isolation reduces gene flow between populations.
5) Over time, colonial populations become genetically divergent from their parent population due to natural selection, mutation, and/or genetic drift

15. Island Biogeography
Explain Robert MacArthur and E.O. Wilson’s Theory of Island Biogeography? How is this theory applied to the management of National Parks?

16. Critical Roles of Keystone Species
Pollination of flowering plant species
Dispersion of seeds by fruit-eating animals
Habitat modification (Gopher tortoise)
Predation by top carnivores to control populations of various species
Improving the ability of plant species to obtain soil minerals and water
Efficient recycling of animal wastes

17. Sea Otter: A keystone species

18. Sea otters feed on the sea urchin which eats the base of the kelp plants (killing the kelp plants)

20. The Dodo bird inhabited the island of Mauritius in the Indian Ocean

21. In 1505, the Portuguese became the 1st humans to set foot on Mauritius
Dodo bird source of food for the sailors
Dutch used the island as a penal colony and brought pigs and monkeys which ate the eggs of the dodo bird

22. The last dodo bird was killed in 1681
A combination of human exploitation and introduced species significantly reduced the dodo population
The last dodo bird was killed in 1681

23. Scientists discovered a certain species of tree was becoming quite rare on Mauritius. All of the remaining trees of their species were about 300 years old and no new trees had germinated since the late 1600’s.

24. Was it coincidence that the tree had stopped reproducing 300 years ago and that the dodo bird had become extinct 300 years ago?

25. The dodo ate the fruit of the tree and the seed only became active and could grow after passing through the digestive tract of the dodo bird.
Scientists discovered the turkey’s digestive tract accomplishes the same task and they are now using turkeys to begin a new generation of the tree - Tambalacoque

26. Biological indicator species are unique environmental indicators as they offer a signal of the biological condition of a particular habitat.
Using bioindicators as an early warning of pollution or degradation in an ecosystem can help sustain critical resources

27. Fish are an excellent indicator of watershed health because:
Live in water all of their life
Differ in their tolerance levels to amount and types of pollution
Are easy to collect
Live for several years
Are easy to identify

28. Benthic macroinvertebrates are good indicators because:
Live in water for all or most of their life
Stay in areas suitable for their survival
Are easy to collect
Differ in their tolerance to amount and types of pollution
Are easy to identify
Often live for more than one year
Have limited mobility
Are integrators of environmental condition

29. Possible Causes of Amphibian Declines
Loss of habitat
Prolonged drought
Pollution (pesticides, nitrates, pH)
Increases in ultraviolet radiation
Increase parasitism
Overhunting
Epidemic diseases
Immigration or introduction of alien predators and competitors

32. Amphibians of all shapes and sizes

33. Five Basic Types of Interactions Between Species
Interspecific competition
Predation
Parasitism
Mutualism
commensalism

34. “sucking” disc does not harm shark
Remora
Commensalism

35. Bacteria in your intestines

36. Significant Niche Overlap – one of the competing species must
Migrate to another area
Shift its feeding habits or behavior through natural selection or evolution
Suffer a sharp population decline
Become extinct in that area

37. How Species Avoid Predators
Run, swim, fly fast
Highly developed sense of smell or sight
Protective shells
Thick bark
Spines
camouflage
Parts that break off
Chemical warfare
Warning coloration
Behavioral strategies
Puffing up
Mimicry
Schooling
Living in large groups
Spreading their wings

38. Avoiding predators

40. Examples of Primary Succession
Bare rock exposed by glacial retreat or severe soil erosion
Newly cooled lava
An abandoned highway or parking lot
Newly created shallow pond or reservoir

42. Pioneer species start soil formation process by:
Trapping wind-blown soil particles and tiny pieces of detritus
Producing tiny bits of organic matter
Secreting mild acids that slowly fragment and break down the rock
Lichen

43. Examples of Secondary Succession
Abandoned farmlands
Burned or cut forests
Heavily polluted streams
Land that has been dammed or flooded

45. Three Aspects of Stability
Persistence – resist disturbance
Constancy – keep within limits
Resilience – bounce back

46. Does species diversity affect ecosystem stability?
Simple ecosystem food web vs. complex and more diverse ecosystem
Elimination of one species from complex ecosystem has little effect on rest of food web (unless it was a keystone species)
Arctic tundra less stable than temperate deciduous forest – result is arctic tundra experiencing drastic population shifts

47. Immature Ecosystem vs. Mature Ecosystem
Small plant size
Low species diversity
Simple food web
Mostly generalized ecological niche
Mostly producers, few decomposers
Efficiency of nutrient cycling is low
Large plant size
High species diversity
Complex food web
Mostly specialized ecological niche
Mixture of producers, consumers, decomposers
High efficiency of nutrient cycling

48. Negative feedback loops promote stability in a dynamic system
Role of positive and negative feedback loops in the stability of an ecosystem
Negative feedback loops promote stability in a dynamic system
Positive feedback loops usually leads to one or more populations being wiped out (local extinction)
Positive feedback loop = causes a system to change further in the same direction (positive refers to the direction of change, rather than desirability of the outcome)
Negative feedback loop = causes a system to change in the opposite direction

49. Positive feedback loop
A warmer atmosphere will melt ice and this changes the Earth’s albedo which further warms the atmosphere
An increase in temperature will melt the permafrost in the tundra causing a release of trapped carbon dioxide and methane (both are greenhouse gases)

50. Negative feedback loop
Predator-prey relationship
The moose population will rise and fall in response to the wolf population

51. Positive and negative feedback loops coupled together
The settlers of Easter Island found plenty of natural resources
The Islanders had many children and the population went up
The island’s tree and soil resources were used faster than they could be renewed
Without trees Islanders could not build traditional seagoing canoes
All of the island’s natural resources were used up
Both the population and the civilization collapsed

52. Example of negative feedback loop
An example of negative feedback is body temperature regulation. If blood temperature rises too high, this is sensed by specialized neurons in the hypothalamus of the brain. They signal other nerve centers, which in turn send signals to the blood vessels of the skin. As these blood vessels dilate, more blood flows close to the body surface and excess heat radiates from the body. If this is not enough to cool the body back to its set point, the brain activates sweating. Evaporation of sweat from the skin has a strong cooling effect, as we feel when we are sweaty and stand in front of a fan.
Read more: Homeostasis - Biology Encyclopedia - cells, body, examples, function, human, process, system, organisms, blood

53. Example of positive feedback loop
An example of its beneficial effect is seen in blood clotting. Part of the complex biochemical pathway of clotting is the production of an enzyme that forms the matrix of the blood clot, but also speeds up the production of still more thrombin. That is, it has a self- catalytic , self-accelerating effect, so that once the clotting process begins, it runs faster and faster until, ideally, bleeding stops. Thus, this positive feedback loop is part of a larger negative feedback loop, one that is activated by bleeding and ultimately works to stop the bleeding. Read more: Homeostasis - Biology Encyclopedia - cells, body, examples, function, human, process, system, organisms, blood