Ch. 20

1. Ch. 20 Community Ecology

2. What is predation? • Predator eats prey

3. What are three adaptations of predators? • What makes them good at finding, capturing, and consuming prey? • acute smell • heat sensing pits • venom • sticky webs • teeth/mouthparts • camouflage • speed

4. List three adaptations of prey? • What makes them good at escaping, avoiding, or warding off predators? • fleeing • hiding • warning coloration • resembling something inedible • deceptive markings • chemical defenses

5. What is mimicry? • One species resembles another

6. What are the two types of mimicry? • Batesian – harmless species resembles a harmful one • Mullerian – 2 or more dangerous or distasteful species look similar

7. What are some plant prey adaptations? • Thorns, spines, sticky hairs, tough leaves, chemical defenses

8. Define interspecific competition • Two or more species using the same limited resource Intraspecific – same species competing Interspecific – different species competing

9. Competitive Exclusion • A species is eliminated from a community because of competition

10. What is symbiosis? • Close long-term relationship between two organisms. • 3 types: • Parasitism (-/+) • Mutualism (+/+) • Commensalism (+/0)

11. Parasitism : one benefits (parasite), one is harmed (host) • Exp. fleas, ticks, tapeworms

12. Mutualism: both benefit • Exp. ants and acacia trees

13. Commensalism: one benefits, other is neither helped nor harmed • Exp. cattle egrets and cape buffalos, sharks and remoras

14. Patterns in Communities Succession

15. What is succession? • Gradual sequential re-growth of a community.

16. Ecological succession • Gradual, sequential regrowth of a community • years or decades • usually after a disturbance Mt. St. Helens

17. What’s the difference between primary and secondary succession? • Primary – no soil previously; area previously did not support life • Secondary – soil already intact; follows disruption of a pre-existing community

18. { makesoil Primary succession • Begins with virtually lifeless area without soil, then… • bacteria • lichens & mosses Once there’s soil, other plants can grow: • grasses • shrubs • trees

19. When is primary succession likely to occur? • On bare rock • Sand dunes • After volcanic eruption • On concrete (like an abandoned parking lot)

20. What is a pioneer species? • First species in an area • Predominate early succession • Characteristics: small, grow quickly, reproduce quickly, disperse seed easily

21. What organisms are typically found in the early stages of primary succession? • Lichens – form soil → Grasses/weeds → Mosses → Eventually larger plants and finally trees • Large conifers may be found in the end stage of primary succession in northern latitudes (pines, balsams, spruces)

22. Secondary succession • Existing community cleared, but base soil is still intact burning releases nutrients formerly locked up in the tissues of tree the disturbance starts the process of succession over again

23. When is secondary succession likely to occur? • After forest fires, strong storms, farming, logging, mining

24. Organisms found in early stages of secondary succession? • Weeds → Perennial grasses and shrubs → Hardwood trees eventually (deciduous forest)

25. Climax Community • Plant community dominated by trees • Representing final stage of natural succession for specific location • stable plant community • remains essentially unchanged in species composition as long as site remains undisturbed • birch, beech, maple, hemlock • oak, hickory, pine