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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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Chaparral
limited evergreen shrubs, densely thicketed highly seasonal mild wet winters and dry summers experience fires in summer California, Mediterranean coast, Chile,
southern Australia
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Altitude Patterns similar to those created by Latitude
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