Creative Community Ecology

1. Creative Community Ecology Ch 54 notes

2. I. Introductory Vocabulary • Community • group of populations in an area or habitat

3. II. Interspecific Interactions • Relationships between the species of a community • Types include:

4. A. Competition • Detrimental to both species • Organisms compete for available resources such as food, water, shelter, sunlight

5. 1. Competitive exclusion principle • Two species so similar that they compete for the same limiting resource cannot coexist in the same place

6. 2. Ecological niche • sum total of a species’ use of biotic and abiotic resources – how an organism fits into it’s ecosystems (it’s role) • two species cannot coexist in a community if they occupy the same niche

8. 3. Resource partitioning • if two species have the same niche, the less competitive one will either be driven from the area, or will evolve through natural selection to use a different set of resources

9. 4. Character displacement • The tendency for characteristics to be more divergent in sympatric (geographically overlapping) populations of two species than in allopatric (geographically separate) populations of the same two species

10. B. Predation • beneficial to one organism but not the other • one organism eats another • includes herbivory (eating part of a plant), parasitism (parasite living on host)

11. 1. Predator adaptations • acute senses to locate prey • many have claws, teeth, fangs, stingers, poison • generally fast and agile if they have to pursue prey

12. 2. Animal defenses against predators • Passive defenses: hiding, chemical toxins • Active defenses: escaping, defending themselves, warning calls

13. Animal defenses against predators • Adaptive coloration • camoflauge – cryptic coloration to blend with environment • aposematic coloration – bright coloration of animals that have chemical toxins dangerous to predators Can you see me?

14. Animal defenses against predators • Mimicry – “copycat” adaptation • Batesian mimicry – harmless species mimics a harmful model (ex. larvae puffs up and resembles cobra) I’m Harmless!!!

15. Animal defenses against predators • Mullerian mimicry two unpalatable species resemble each other • predators learn more quickly about danger of the appearance

16. 3. Parasites and Pathogens as predators • host harmed in the process • endoparasites – live within their host (tapeworm) • ectoparasites – feed on external surface of host (mosquito) • parasitoidism – insects lay eggs on living host

17. 4. Herbivory Organism eats part of a plant or alga ex. Cattle, many invertebrates, manatee Herbivores may have adaptations such as chemical sensors to detect toxins, specialized teeth

18. 5. Plant defenses against herbivores • Chemical toxins • Spines • Thorns • Used since plants cannot run from predator

19. C. Mutualism • interspecific interaction that is beneficial to both species • often requires coevolution of adaptations in both species • if one is harmed, the other is usually harmed as well

20. Examples of Mutualism • microorganisms in digestive system of termites and ruminants (help digest cellulose) • Photosynthesis by algae in tissue of coral There’s bacteria in my belly Who knew!!!

21. 4. Commensalism • interaction between species that benefits only one of the species but no harm to the other • ex. algae growing on shell, birds eating insects flushed up by cows Yummy Bugs MOOOO

22. III. Biodiversity • Species diversity in a community

23. Species Diversity • The variety of different kinds of organisms that make up the community

24. Species Diversity • Species Richness • number of species that a community can contain • Relative Abundance • The proportion of each species represents of all individuals in the community

25. Which community is more diverse???

26. Community 1 and 2 are equal in their species richness (both have 4 different species) • Community 1 is more diverse because there is equal representation of all 4 • Community 2 has a large amount of Species A • Community 1 has greatest heterogeneity (looks at species number and relative abundance

27. IV. Trophic structures • feeding relationships between organisms

28. A. Food Chain • Transfer of food energy from it’s source in plants through herbivores to carnivores and eventually to decomposers • Each link makes a trophic level • Each food chain has only four or five links due to inefficient energy transfer as you move up the chain • Longer food chains may not be able to recover as quickly from environmental change

30. B. Food Web • more than one food chain hooked together

31. Dominant species • have the highest abundance or the highest biomass • exert control over occurrence and distribution of other species

32. Keystone species • exert control on community structure by their ecological role (niche) • may help to maintain diversity and balance in community • ex. sea otter eats sea urchin eats algae • remove sea otter (keystone) and algae population goes down • add sea otter – algae population increases

33. Example of Keystone Species • Removal experiment • Robert Paine and Sea Star – Pisaster is a keystone predator of mussels • With Pisaster – many species able to coexist • Without Pisaster – mussels able to overtake area eliminating many other species

35. Foundation Species Exert influence on a community by causing physical changes in the environment ex. Beaver building a dam can transform the landscape on both sides Can be positive or negative on other species

36. V. Disturbances • storms, fires, floods, drought, overgrazing, human activities • may upset balance or equilibrium in community

37. Ecological succession • transition in the biological species composition of a community usually following a disturbance

38. Primary succession • succession that begins in a virtually lifeless area where soil has not yet formed (like Hawaii) • Autotropic bacteria  lichens/mosses soilother plants animals

39. Secondary succession • existing community has been cleared by a disturbance that leaves soil intact • Often these areas return to something like the original state