1. COMMUNITY ECOLOGY

2. OBJECTIVES: Describe types of relationships among organisms. Compare primary and secondary succession.

3. Community Interactions Community = a group of populations of different species living close enough to interact. Types of Interactions: Competition, Predation, Symbiosis.

4. Competition The competitive exclusion principle states that when two species compete for the same resource or niche, eventually the one with the slight reproductive advantage will eliminate the other.

5. Predation A true predator kills and eats the other animals (prey). A parasite spends most or all of its life living on another organism (host) and feeding on its tissues. A herbivore is an animal that eats plants.

7. Symbiosis Symbiosis = “living together”; several types: Mutualism = both species benefit.

8. Parasitism = one organism benefits and the other is harmed.

9. Commensalism = one organism benefits; the other is neither harmed nor benefited.

10. Ecological Succession http://www.y outube.com/ watch?v=V4 9IovRSJDs

11. Succession – gradual change in the composition of species over time; frequently following a disturbance. 1. Primary succession - succession on a new site by pioneer species such as lichens; eventually larger plants replace the pioneer species. Lichen = fungus living with algae or cyanobacteria (mutualism). Example: colonization after volcanic eruption.

12. Primary succession

13. 2.Secondary succession – changes occurring where soil and vegetation already exist. Example: gradual changes after a fire.

14. Climax community = stable, mature community that undergoes little succession. Secondary succession

15. Hmm… 1.Does primary or secondary succession take longer? Why? 2.Are pioneer species r-selected or K-selected species? 3.How do species cause changes in the habitat that will result in different species composition?

16. Species Diversity = measures the number of different species in a community and the relative abundance of each species. Dominant species have the highest biomass (the sum weight of all members of a population). Keystone species have a strong influence on the survival of other species; their removal results in dramatic changes in the makeup of species in a community. Keystone species examples: sea otter, grizzly bear, wolf.

17. Invasive species: http://www.youtube.com/watch?v=HAY_UsGjyZk An introduced (non-native) species that may compete with native species for resources such as food, space, and water. Examples: tamarisk, zebra mussels, kudzu. Note: Most non-native species are not invasive.

18. Hmm… How do keystone species maintain balance in ecosystems? How does the introduction of a non-native species influence the balance of an ecosystem?

19. MATH CONNECTION The daily caloric requirements for male versus female killer whales (orcas) is shown below: Male killer whale: 308,000 kcal/day Female killer whale: 187,000 kcal/day Calculate the average caloric value of a sea otter assuming a male orca consumes five sea otters each day to meet its caloric requirement. Give your answer to the nearest hundredth.