11/22/20161 Ecosystem Dynamics

11/22/20162 Community All populations living and interacting in one area. Community dynamics include… Diversity of org.’s Vegetation Stability Trophic Structure

11/22/20163 Diversity Variety of organisms… The number of different types of organisms…the more different types the greater the diversity. The abundance of the different types of species.

11/22/20164 Vegetation The dominant types of plants in the area. The vertical structure of the plants.

11/22/20165 Stability Ability of a community to resist change and return to original spp. composition. Ex. Forest is stable due to enduring populations & can resist change…but slow to regrow if fire damaged.

11/22/20166 Ex. Grassland is unable to resist change due to fire…but is quick to regrow when damaged.

11/22/20167 Trophic Structure The feeding relationships among spp. in a community. Producers= Plants that “produce” (create) the most energy in a community.

11/22/20168 *Derive energy from the sun. *Produce energy for the entire community of consumers and decomposers.

11/22/ Consumers= Need to “consume” (eat) their food because they cannot make their own food. Primary, Secondary and Tertiary Consumers

11/22/ Decomposers= certain Bacteria and certain Fungi that break down dead org.s to their original nutrient compounds.

11/22/ Competition INTERSPECIFIC COMPETITION happens when two populations require the same limited resource. Ppln’s may Flee or Die as a result of the ensuing battles for the resource.

11/22/ Competetive Exclusion Principle In 1934 Russian ecologist G.F. Gause concluded that “two species so similar that they compete for the same limiting resources cannot coexist in the same place.”

11/22/ “One will use the resources more efficiently and thus reproduce more rapidly. Even a slight advantage will eventually lead to a local elimination of the inferior competitor.”

11/22/ Niche The role an organism plays in the environment. Usually refers to if the org. is a producer, consumer or decomposer… in the food web. The sum total of an org.’s use of abiotic and biotic resources in the env.

11/22/ Predation An interaction where one spp. (predator) eats another (prey.) No spp. is really free from predation, especially the youngest in the ppln., unless…

11/22/ the org. grows really big (elephant) the org. can flee or hide the org. is camouflaged the org. is armored, spiny or emits a noxious chemical defense

11/22/ A predator can have an advantage is it is *fast, *has agility *has ambush tactics and *has counter defense tactics

11/22/ COEVOLUTION A series of reciprocal adaptations in two spp. A change in one spp. acts a selective force on another spp. and counteradaptations of the second spp. in turn affects the selection in the first spp.

11/22/ Defense Mechanisms Chemical toxins, spines, thorns, quills, camouflage, mimicry; Batesian Mimicry & Mullerian Mimicry

11/22/ Batesian Mimicry A palatable (yummy) org. mimics (looks like) one that is yucky tasting. Mimic must be fewer in number than the copied org.

11/22/ Mullerian Mimicry When two unpalatable org. mimic one another. Helps both because their numbers are then higher and predators will learn to avoid them better.

11/22/ Keystone Predators Spp. that reduces the density of the strongest competitors. Predators help maintain species diversity by preventing competitive exclusion of weaker spp.

11/22/ Symbiotic Relationships An interaction between two or more spp. in which one spp. lives in or on another spp. 1. Parasitism 2. Commensualism 3. Mutualism

11/22/ Parasitism Predator / Prey reln. in which on org. (parasite) derives its food at the expense of the host. Predator survives nicely. Host is harmed but not necessarily killed…if host died the parasite would die also.

11/22/ Commensualism A relationship where one org. benefits and the other is unaffected. Very uncommon reln. Because it is unusual for an org. not to be affected in some way.

11/22/ Mutualism A relationship when both org.s benefit. Bacteria on our skin…bacteria gets food and we don’t get foreign bacterial infections.