Chapter 6: Species Interaction & Community Ecology

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

Symbiosis Amensalism Amensalism: one is harmed while the other is unaffected. This is difficult to observe. Commensalism Commensalism: 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 consumers primary consumers: consume producers – anchovy consumes plankton secondary consumers secondary consumers: predators that prey on primary consumers – tuna and comorant, both eat small fishes tertiary consumers tertiary 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 whale sea birdseal 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 Succession Primary Succession follows a disturbance so severe that no vegetation or animal life is left – glacier – fires

Secondary 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 community Climax 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.

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 THE END