APES UNIT 2: ECOLOGY

1. APES UNIT 2: ECOLOGY = the study of how organisms interact with each other and their environment

2. I. Ecosystem Factors • A. Abiotic • 1. Climate 4. minerals • 2. Soil 5. contaminants • 3. Water 6. Etc. • B. Biotic • 1. Animals 4. Bacteria • 2. Plants 5. Protists • 3. Fungi

3. II. Organisms • A. Adaptation (Evolution) • 1. Based on genetics and natural selection • 2. When biotic or abiotic factors change, a species may: • adapt • migrate • go extinct

4. B. Niche = an organism’s place in the ecosystem • 1. Determined by: • a. how it deals with abiotic factors • b. how it gets food, what its food is • c. how it reproduces • d. range of tolerances • e. etc. (everything about the organism, except habitat)

5. 2. Niche breadth • = what’s included in a niche, especially whether an organism is a generalist or a specialist • 3. Niche overlap • = when 2 species share part of their niches • 1. Usually results in Niche Partitioning (adaptations to limit competition) • 4. Competitive Exclusion Principle • = No 2 species with identical niches can coexist indefinitely at the same time and space

6. Niche separation Number of individuals Generalistspecies with a broad niche Generalistspecies with a narrow niche Niche breadth Region of niche overlap

7. III. Populations= groups of interbreeding organisms, all of the same species in physical proximity to each other • A. Population Curve • graph of number of organisms in a population over time 1. J- curve exponential growth 2. S-curve stable population

8. B. Limiting Factors • resources that stop a population’s growth • C. Carrying capacity • the population an ecosystem can support or the population when a limiting factor is reached

9. D. Threshold Population • the smallest size a population can get and still recover • E. Balance • biotic potential ( all factors that help an organism reproduce) • vs. • Environmental resistance ( all the potential limiting factors) • F. Extinction • If balance can’t be reached, organism may all die

10. G. Mechanisms of Population Balance • 1. Predator-prey (+,-) • 2. Host-parasite (+,-) • 3. Competition (-,-) (interspecies or intraspecies) • 4. Plant-herbivore (+,-) • 5. Fire • 6. Territoriality • 7. Symbiosis • a. mutualism (+,+) c. parasitism (+,-) • b. commensalism(+,0)

11. H. Density Dependence • 1. Density Independent Regulation • a. event affects populations no matter how dense they are • b. catastrophic occurrences, in extreme environments • c. examples: fire, hurricane, tornado • d. greatest effects on small organisms, low trophic levels

12. 2. Density Dependent Regulation • a. event has greater effect on a population when the population is more dense • b. event is usually resource based • c. examples: food, disease, predation, water • d. greatest effects on large organisms, higher trophic levels

13. I. Life-History Strategies • 1. r-selection • Characteristics • many offspring good dispersal • poor competitors density independent reg. • Opportunists-weeds, pests • 2. k- selection • Characteristics • parental care- few offspring larger size • constant environment good competitor • long lifespan

14. IV. Community= all the organisms in a specific area • A. Biodiversity • 1. = the variety of organisms in an ecosystem • 2. Can vary,some are very diverse (rainforest, coral reef, salt marsh) and some are not very diverse (farm field, grassland, northern evergreen forest) • 3. Diverse ecosystems usually more stable, more productive, more interesting

15. B. Measuring Biodiversity (use indices) • 1. Species Richness (S) • equals number of different species • Sample Data • Species A B C D E F G H I J • Habitat 1 1 1 1 1 1 1 1 1 1 141 • Habitat 2 15 15 15 15 15 15 15 15 15 15

16. 2. Shannon-Wiener Index • H’ = - Pi ln (Pi) • ( Pi= percentage of species “i”) • 3. Simpson Index • D= 1/  Pi2

17. C. Ecological Succession • = the predictable change in the community make-up of an ecosystem over time, especially after a disturbance

18. 1. Types of Succession (pg.) • a. Primary Succession • starts with an area that has not been previously inhabited by land plants • examples= bare rock, volcanic island, filled pond • b. Secondary Succession • re-establishing an area that was previously inhabited • examples= after a fire, deserted farm, after a storm

19. 2. Each stage prepares the way for the next • 3. Climax Community • a. = the plant community that exists when succession leads to a balance and stops changing • b. the climax community is specific to different locations • deciduous forest in Maryland • rainforest in Brazil

20. V. Ecosystems • A. Characteristics • 1. Involve biotic and abiotic parts • 2. Involves energy flow ( sun is usually source) • 3. Exchange of materials - cycles • 4. Become more complex as they mature • 5. Can vary in size

21. B. Biomes= large terrestrial ecosystems,determined by climate and plant community (pg.130-149) • 1. Temperate Forest • 2. Grassland • 3. Desert • 4. Coniferous Forest – Taiga,Boreal Forest • 5. Tundra • 6. Savanna • 7. Tropical Rainforest

22. C. Aquatic Ecosystems • 1. Freshwater • a. Lakes and Ponds • Two Zones • Stratification • Seasonal mixing in temperate zones • Stable ecosystem

23. b. Wetlands • = covered with water part of the time • marsh, swamp, floodplain, bog • Very productive • good habitat (breeding, migrating) • absorb pollution, water • endangered

24. c. Rivers and Streams • in motion- water, sediment, pollution • organisms adapt to flow rate - faster has more oxygen

25. 2. Saltwater • a. Estuaries • where freshwater meets saltwater • bays or gulfs • very productive- often shallow • organisms adapted to changing environment- salinity, temperature, tide

26. b. Coral Reef • made from shells of coral animals, in warm oceans • large biodiversity- like rainforest • endangered from pollution, exploitation • c. Ocean • covers 3/4 earth- large • surface is most productive • many adaptations • d. Coastal • harsh conditions - waves, tides, exposure