Ecology

Ecosystems and Communities

Weather vs. Climate

• Weather is the condition of the Earth’s atmosphere at a particular time and place.

Atmosphere is the Earth’s “insulating blanket”

• Climate is the average yearly condition of temperature and precipitation in a region.

Climate is caused by:

• Latitude

• Winds and ocean currents which transport heat through the biosphere (unequal heating)

• Shape and height of landmasses

Greenhouse EffectThe temperature on Earth stays suitable for life

due to the trapping of heat by gases in the atmosphere causing a natural phenomenon called the Greenhouse Effect.

Phenomenon – an occurrence or fact that can be perceived by the senses.

Climate Zones

Three main climate zones:1. Polar – very low angle2. Temperate 3. Tropical – near the equatorCaused by differences in heating of the Earth’s

surface.• Latitude• Unequal heating of the surface results in currents

• Wind currents occur because warm air rises and cool air sinks.

• Where would you expect to find warm air rising? Cold air sinking?

• The same pattern occurs in the ocean’s.• Wind over the water’s surface also creates

currents.• Landmasses also have affect on currents.• Example: Rain shadow

Latitude determines the angle of the sunlight striking the earth

What Shapes Ecosystems

• Biotic – Biological or living factors that influence organisms in an ecosystem

Ex. Plants and animals• Abiotic – Physical or non-living factors that

influence organisms in an ecosystemEx. Temperature, soil type, sunlight, etc.

Habitat

• The area where an organism lives• Contains both biotic and abiotic factors

Niche

• Full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

An organism’s habitat is its address; its niche is its occupation.

Example: Lion lives in the savannah but it survives in that habitat by being a top level consumer.

Example of Niche for Anoles Lizard

Community Interactions

• Competition• Predation• Symbiosis

MutualismCommensalismParasitism

Competition

• This occurs when organisms try to use the same *resources (necessities of life).

• Often results in one organism dying out

Competitive Exclusion Principle – No two species can occupy the same niche in the same habitat at the same time

Predation

One organism (predator) captures and feeds on the other (prey)

Symbiosis

• Occurs when two species live closely together• Three types:1.Mutualism2.Commensalism3.Parasitism

MutualismBoth species benefit from the relationship

CommensalismOne species benefits while the other

is neither helped nor harmed

ParasitismOne species benefits by living in or on

the other and the other is harmed

Ecological Succession

• The series of predictable changes over time is succession.

Ecosystems constantly change due to natural and human influences. Ex: Further disturbances, long term climate changes, introduction of non-native species

Primary Succession occurs on bare rock surfaces where no soil exists.Ex: Lava flow or glacier melt

*Pioneer species are the first species to populate an area following a disturbance that causes primary succession.

Ex: Lichens

Secondary Succession occurs when a disturbance changes a community without

removing the soil

Climax communities are those that seem to be stable and undergoing no more change.

Changes may occur very slowly due to climate changes or introduction of non-native species

Biomes

• Biomes are groups of communities that cover large areas and are characterized by certain soil and climate conditions and particular assemblages of plants and animals.

• Each biome is identified by its particular set of abiotic factors and characteristic ecological community and organisms.

Tolerance - plants and animals ability to survive under conditions that differ from their optimal (most desirable or favorable) conditions

Microclimate – climate conditions in a small area that differ significantly from the climate of the surrounding area

Aquatic Ecosystems• Determined by depth, flow, temperature, and

chemistry of the water (salts, nutrients and oxygen).

• Grouped by the abiotic factors that affect them (different than land biomes which are determined by biotic factors)

• Three main categories of Aquatic Ecosystems1.Freshwater2.Estuaries3.Marine

Freshwater Ecosystems

• Flowing water: Rivers, streams, creeks, and brooks

• Standing-water: Lakes and pondsPlankton- tiny organisms that live in fresh or saltwater environmentsPhytoplankton - single-celled algae are producers

in aquatic food websZooplankton – tiny animals that feed on

phytoplankton

• Freshwater wetlands: an ecosystem that has water covering the soil or is present at or near the surface for a portion of the year

• Very productive ecosystems; important breeding grounds for organisms (birds and insects)

• Bogs, marshes and swamps• Water can be flowing or standing and fresh,

salty or brackish(mixture of fresh and salty)

Estuaries• Wetlands formed where rivers meet the sea• Contain a mixture of fresh water and salt

water• Affected by tides• A lot of detritus (organic material that provide

food for organisms at base of food web) from primary producers

• Examples: Salt marsh-Chesapeake Bay and Mangrove swamp-Florida Everglades

Marine Ecosystems

• Photic Zone - well-lit upper layer; producers can photosynthesize here (0 to 200 meters)

• Aphotic Zone – Sunlight can not penetrate due to depth (200 meters and deeper)

• Other zones based on depth and distance from shore: intertidal zone(close to shore), coastal zone, open ocean, benthic zone(ocean floor)