Chapter 6: Species Interaction & Community Ecology

Chapter 6: Species Interaction & Community Ecology

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Species Interaction

competition predation parasitism symbiosis

– mutualism– amensalism– commensalism

herbivory

Competition

limited resources seeked by multiple species (density dependant)

organisms– food– shelter– water– mates– sunlight

Intraspecific: between different species Interspecific: amongst individuals of the same

Intraspecific Competition

may exclude another species, also known also as competitive exclusion– example: zebra mussel

may coexist without interfering, also known as species coexistence. – example: rat and mongoose in Hawaii

Predation

structures the food web influences community composition helps determine the relative abundance of predator

and prey– zebra muscle preys mostly on phytoplankton and some

zooplankton– these populations dropped 70% in Lake Erie and Hudson

River, but cyanobacteria are not predated so their population increased.

– populations of ducks, muskrats, crayfish, flounder, sturgeon and eels prey on zebra muscle

Parasites

exploits other organisms without killing them immediatly, but may eventually cause death.

depends on the host for nourishment or other benefit while harming the host.

– internal parasites: tapeworm, malaria, cholera, etc– external parasites: ticks, fleas, sea lamprey

CoevolutionCoevolution: : host and parasite, as one changes, the other evolves to keep the interaction between them occuring

Herbivores

eat plants plants evolve defence mechanisms

– toxic or distasteful chemicals– volatile chemicals that atract predators– thorns– swelled stems where ants live and protect it

Symbiosis

MutualismMutualism: relationship in which 2 or more species benefit from– mycorrhizae– human digestive tract and bacteria– pollinating plants and bee

Symbiosis

AmensalismAmensalism: one is harmed while the other is unaffected. This is difficult to observe.

CommensalismCommensalism: one species benefits and the other is unharmed.– epiphytes growing on other plants– barnacles attached to whales– clown fish living in anemonies

Trophic Levels

producers consumers detrivores decomposers


Producers

autotrophs first trophic level

– green plants, cyanobacteria, algae use photosynthesis

– chemosynthetic bacteria uses geothermal energy

Consumers

primary consumersprimary consumers: consume producers– anchovy consumes plankton

secondary consumerssecondary consumers: predators that prey on primary consumers– tuna and comorant, both eat small fishes

tertiary consumerstertiary consumers: higher lever of predator– owls and hawks

Detrivores

scavenge the waste products or dead bodies of other community members– condor or vultures– millipedes– beetles

Decomposers

break down the material into its simple compounds plants can use– fungi– bacteria

Energy and Biomass

some energy is lost as waste heat every trophic level has some energy loss next trophic level has less energy available energy loss varies pyramid


Food Web

condor

killer whalesea bird seal

tuna

anchovie

plankton

Keystone Species

indicator of the condition of the ecosystem as a whole

usually found at top of food chain– sea otter › feeds on urchins › feed on kelp– kelp maintains a balanced ecosystem

Disturbances

removal of keystone species– sea otter eaten by killer whales

spread of invasive species– kudzu

climate change– retrieve of a glacier

sudden events– hurricanes– floods– avalanches– volcano eruption

Responce to Disturbances

resistance: show no change even under presence of a disturbance

resilience: may show a change, but later returns to its original state

may show change and never return to its original state

Succession

changes in an ecosystem that follow a disturbance Primary SuccessionPrimary Succession follows

a disturbance so severe that

no vegetation or animal life

is left– glacier– fires


Secondary SuccessionSecondary Succession

follows a disturbance that not necessarily destroyed all living things, some are left and those are the building blocks of the future community– Mt. Saint Helen

Climax communityClimax community remains in place with little modification until the next disturbance occurs

Invasive Species

non-native species that spreads widely becoming a dominant species

can potentially alter the community introduced by accident limiting factors are removed or not present

– predator– competitor– parasites– weather change

ecological restoration

Kudzu


Biomes

major regional complex of similar communities distinguished by a dominant plant

cover large geographic areas largely in function of the climate best indicators of an area's climate aquatic systems also show biome patterns altitude can vary biomes due to climate change, as

you climb mountains, the biomes change in vegetation and animal species

Terrestrial Biomes

temperate deciduous forest temperate grassland temperate rainforest tropical rainforest tropical dry forest savanna desert tundra boreal forest chaparral

Temperate Deciduous

loses leafs precipitation is spread evenly through the

year relatively fertile soils fewer species oak, beeches, maples central and southern Great Lakes


Temperate Grassland

more extreme summer and winter temperatures

limited amount of precipitation grasses are supported more easily than trees today mostly used for agriculture bison, prairie dogs, antelope


Temperate Rainforest

heavy rainfall coniferous trees interior of forest is shaded and damp fertile soil soil susceptible to erosion if trees are cut

down north west of the US


Tropical Rainforest

high rainfall dark and damp lush vegetation highly diverse communities high number of different trees at low density poor acidic soils, not proper for farming closer to the equator: Central and S.America, Asia uniform warmer temperatures year-round


Tropical Dry Forest

warm year-round but highly seasonal precipitation

India, Africa, S.America, N. Australia can be converted to agriculture native plants adapted to the seasonal rains

growing during wet season and become dormant during dry season.

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Savanna

grassland with occasional clusters of trees Africa, S.America, Australia, India distinctive rainy season animals migrate according to rain water holes formed by rain


Dessert

driest biome, well under 25cm of rain/year isolated storms months or years apart vegetation depends on the rain amount

– Sahara: very little rain– Sonora: enough rain to sustain vegetation

temperature variation may be dramatic anatomical and behavioral adaptations

– large ears to cool down– active at night– green trunk, leathery leaves

and spines


Tundra

Russia, Scandinavia, Canada extremely cold lichens and scrubby vegetation, no trees permanently frozen soil= permafrost migrating birds are attracted to it in summer polar bears and oxen are the few local

species


Boreal Forest

also known as taiga cooler dryer areas long cold winters, short cool summers few species of coniferous trees poor soils, usually acidic animals breed and eat during summer, some

hibernate during winter Canada, Alaska, Russia and Scandinavia


Chaparral

limited evergreen shrubs, densely thicketed highly seasonal mild wet winters and dry summers experience fires in summer California, Mediterranean coast, Chile,

southern Australia


Altitude Patterns similar to those created by Latitude

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Chapter 6: Species Interaction & Community Ecology