Community EcologyCampbell Chapter 53

What is a community?

•All the populations in a given area interacting with each other and their surrounding environment.

Interactions between species

These are interactions between different groups of organisms

Competition•Organisms compete for the same resources: Food, space, mates From http://www.milosphotos.com/wildlife1/dallrams.jpg

Competitive Exclusion Principle (Gause’s)

•Two similar species cannot exist in the same niche

•One will be driven to extinction

Symbiotic relationshipsTwo organisms living together in a relationship

Predation/parasitism

•One organism feeds on another for food

•One is benefited, one is harmed

From http://www.funkstownvet.com/HEARTWORM.jpg

Herbivory•Type of predation done by herbivores

•Herbivores preying on plants

From http://oneidaswcd.org/grazing%20cow%203.jpg

Secondary Compounds in Plants

•Plants can’t run away, so they produce toxins to deter herbivores

•Ex. aspirin, clove oil From http://www.worldfood.com/images/spices/cloves.jpg

Commensalism•Two organisms live together, and one is helped while the other is not affected

•Ex. hermit crabs

From http://www.ukdivers.net/life/uk/hermit.jpg

Mutualism•Two organisms benefit from living together

•Ex.: ladybugs eat aphids on rosebushes

From http://www.broward.org/naturescape/images/lady-bug-eating-aphids.gif

Ways to avoid predationAnimals have adaptations to avoid being eaten.

Aposematic Coloration

•“Warning” coloration

•Bright colors warn others

•“I taste bad/I bite/I am not to be messed with”

From http://www.sloanmonster.com/images/coral.jpg

Cryptic Coloration•Coloring that

allows the organism to blend into its environment so it can’t be spotted by predators

From www.nicksspiders.com/insects/stickhid.jpg

Mimicry

Some organisms mimic others in order to protect themselves

Batesian Mimicry

•A harmless or palatable species mimics one that is neither harmless nor palatable

Example: Hawkmoth and Snake

•When disturbed, the hawkmoth larva looks like a snake.

Mullerian Mimicry

•Two unpalatable species mimic each other

Example: Monarch vs. Viceroy Butterflies

From http://www.ent.iastate.edu/Imagegal/lepidoptera/monarch/monarchonalf.htmlFrom

http://www.photos-of-the-year.com/nature/showphoto.php?photo=17870

Monarch butterflies taste bad too so birds try to avoid them as well.

Viceroy butterflies taste foul to birds and will make birds regurgitate them when eaten.

Example: Honey Bee and Yellowjacket

From http://www.forestry.caf.wvu.edu/buttonsGood/pics/honeyBee.gif

From http://www.eatonvillenews.net/images/Bob/TONY%20YELLOW%20JACKET%201%20SEPT.%2025,%2005%20135F1366b.jpg

Both species share similar coloring and have poisonous venom

Succession

The replacement of one community with another

Primary Succession

•A community is established in a fairly lifeless area

•First life forms are usually bacteria, then lichens

•Soil eventually develops, then plants are established

Example of primary succession

•A retreating glacier leaves a moraine, a soil-laden area where life has the potential to take root.

Secondary Succession

•Occurs in an area where disturbance has occurred, but the soil is intactAfter a forest fireAfter a hurricane

Example of secondary succession