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Chapter 17Biological Communities

Interactions among species Natural selection:Natural selection has often led to a close match between the characteristics of the flowers of a plant species and its pollinators Co evolutionBack and forth evolutionary adjustments between interacting members of a community

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Predator Prey Relationship

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Predator Prey Relationship

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Predators and prey Co evolve Predators and Prey co evolve Predation is the act of one organism killing another for food.

Ex: lions àzebras Snakes à mice Spiders and centipedes are exclusively predators

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ParasitismOne organism feeds on and usually lives on or in another typically larger hostParasites usually do not kill their host because they depend on the host for food and a place to live Hosts will often transmit the parasites to their offspringExamples: Lice feed on the hosts surface like ticks mosquitoes and fleas Hookworm and tapeworms live entirely within the body of the host.

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Predation is also a problem for plants because plants need to protect themselves from herbivores with thorns, spines or prickles

Example:The cactus plant Secondary Compounds are defensive chemicals.

Example:The mustard plant family produces mustard oils like Cabbage, radish and horseradish (think about your response to these when you smell them!)

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Symbiotic Species Symbiosis is when 2 or more species live together in a close, long term association.

symbiotic relationships can beneficial to:both organisms benefit one organism and leave the other unaffected or harmed. Parasitism is detrimental to the host. Mutualism is a symbiotic relationship in which both participating species benefit

Ex: Ants and aphids

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Symbiotic Species Symbiosis is when 2 or more species live together in a close, long term association.

symbiotic relationships can beneficial to:both organisms benefit one organism and leave the other unaffected or harmed. Parasitism is detrimental to the host. Mutualism is a symbiotic relationship in which both participating species benefit

Ex: Ants and aphids

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Commensalism a symbiotic relationship in which one species benefits and the other is neither harmed nor helped.

Ex: Clownfish and Sea Anemone How competition shapes communities:

Competition is the relationship between species that attempts to use the same limited resource.

Competitors are species that compete for food, nesting sites, living space, light, minerals, nutrients, water

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Niche is the position or “way of life” of a species in an ecosystem in terms of the physical characteristics of the area, where the species lives and the function of the species in the community.

A niche may be described in terms of space utilization, food consumption, temperature range, requirements for moisture or mating or other factors A niche is not a habitat. habitat is a place where organisms live. It is a location. A niche is a pattern of living.

A niche is often described in terms of how the organism affects energy flow within the ecosystem in which it lives.

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Niche

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Fundamental niche­ The entire range of resource opportunities an organism is potentially able to occupy within an ecosystem

Realized niche­This is the part of its fundamental niche that a species occupies

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Competition and Limitations of Resource Use

Competition can limit how species use resources

Ex: 2 different barnacle speciesC. Stellatus­ lives in shallow water often

exposed to air

S. Balanoides­ lives lower down on the rocks and is rarely exposed to air. Joseph Connell­

He removed S. Balanoides from the deep end

C. Stellatus then also occupied the deep zone, which meant the deep zone is part of its fundamental niche

When S. Balanoides was reintroduced they crowded out the C. Stellatus This experiment showed competition could limit resources

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Competitive Exclusion­ is the elimination of a competing species. 1930 G.F. Gauss grew 2 species of Paramecium. These paramecium would compete for the same food (bacteria). The smaller paramecium which was more resistant to bacterial waste products drove the larger one to extinction When it is possible for 2 species to avoid competing, they may coexist Predation and Competition;

Robert Paine­ studied Sea stars and how sea stars affect the numbers and types of species within the intertidal communities

Because predation can reduce competition, it can also promote biodiversity.

Biodiversity is the variety of living organisms present in a community.

Biodiversity is a measure of both the number of different species in a community.

Species richness and the relative numbers of each of the species is species diversity

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Major Biological Communities: Climate­ refers to the prevailing weather conditions in any given area. The climate of any physical environment determines what organisms live there. Temperature­ Most organisms are adapted to live within a particular range of temperatures. Moisture­ all organisms require water (H20). Patterns of rainfall often determine an area’s life forms.

The moisture holding ability of air increases when warmed and decreases when it is cooled.

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Biomes

A biome is a major biological community that occurs over a large area of land. The 7 biomes: 1) Tropical Rain forest2) Savanna3) Taiga4) Tundra5) Desert6) Temperate Grassland7) Temperate forest

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Terrestrial Biomes:

Tropical Rain forest:o Average rain is about 450 cm a yearo The richest biome in terms of the number of specieso Has a high primary productivityo The soil is quite infertile, low in nutrientso The nutrients are held within the plants Sanannas: or the dry grasslands o Low annual rain fall (90­150 cm)o has a wider fluctuation in temperatureo Has a seasonal droughto Open landscape

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Taiga:o Cold and weto Known as Coniferous forests primarily of spruce and fir treeso Is in Eurasia and North Americao The winters are long and coldo Most of the rain falls in the summer Tundra:o Open and mostly boggy (spongy like)o It covers 1/5 of the earth’s land surfaceo It rains less than 25 cm yearlyo Water is not available because it is mostly frozeno Permafrost or permanent ice usually exists within 1m/3 ft of the surface

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Desert:o Gets less than 25 cm of rain a yearo The vegetation is sparseo Most extensive in the interiors of continentso Less than 5% of North America is desert Temperate Grasslands:o Prairieso The soil is deep and fertileo The climate is moderate

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Temperate Deciduous Forest:o Mild climateo Rains between 75­250 cmo Warm summers and cold winterso Deciduous trees shed their leaves Temperate Evergreen Forest:o Drier weathero Different soil conditions favor the growth of evergreenso Can include the Chaparral (California and Mediterranean areas)

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Aquatic CommunitiesFreshwater community includes lakes, ponds and

rivers

Ponds and Lakes have 3 zones:1) Littoral zone­ shallow zone near the shore. Contains aquatic plants, predatory insects, amphibians and small fish2) Limnetic Zone­ an area that is farther away from the shore but close to the surface. You will find floating algae, zooplankton and fish here.3) Profundal zone­ This area is a deep­water zone below the limits of effective light penetration. Here you can find bacteria and wormlike organisms that eat debris on the lake’s bottom. They release large amounts of nutrients. Not all systems are deep enough to have a profundal zone

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WetlandsSwamps, marshes, bogs and other communities that

are covered with a layer of water.

Hydrophytes are water tolerant plants like marsh greases or cattails

Wetlands provide water storage basins for moderate flooding.

You can find a diverse array of invertebrates, birds and other animals Estuaries

Transition zones between marine and freshwater environments

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3 major marine Communities 1) Shallow ocean waterThese waters are inhabited by a large number of species.Intertidal zone­ This area is between low tide and high tideCoral reef community has the world’s most diverse speciesFisheries are coastal zones of cooler waters. The nutrients are washed out from land 2) Surface to open seaPlankton­ composed of bacteria, algae, fish, larvae and many small invertebrates

Photosynthetic plankton form the base of the food chain and account for 40% of all the photosynthesis on Earth. These waters are about 100 meters deep.3) Ocean depthsThese are the deepest waters.Total darkness, deep cold and great pressureThis area supports a diverse community

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