Ecology

Ecology

The study of the interaction between biotic and abiotic factors.

Biosphere

all of the places on earth where life can exist.

Biome

Large regions characterized by a particular geography, climate, flora and fauna.

Ecosystem

A place and all of its biotic and abiotic parts.

Community

All of the living things in an ecosystem.

Population

All of the living things of a particular species in a community.

Organism

The individual members of a population.

Population Dynamics

Exponential Growth

Growth without limits. Population growth when there is plenty of food, water, space, shelter, no disease, no predators, etc. Also called Biotic Potential. Human are the only species that can somewhat maintain exponential growth.

Logistic GrowthGrowth with limits. Reflects

population growth in response to limiting factors.

Limiting FactorsAnything that limits the growth of a

population. The sum total of all limiting factors is environmental resistance.

Ex. Food, water, shelter, space, predators, disease, etc.

Density Dependent L.F.

Limiting Factors which are impacted by population size.

Ex. Competition for resources

Density Independent L.F.

Limiting factors which are not impacted by population size.

Ex. Natural disasters, fires, freezes, etc.

Carrying Capacity

The average population that can be supported by an ecosystem over time due to the presence of limiting factors.

Interactions between Populations

Predator/Prey relationships

Predator hunts, catches and eats prey. Examples: Cheetahs eat Gazelles, Bobcats

and Rabbits, Frogs eat crickets, Crickets eat grass.

Symbiotic Relationships- when organisms of different species are interdependent.

Parasitism- one organism is harmed, one benefits. Ex. Ticks on dogs, Tapeworms in humans.

Mutualism- both organisms benefit. Ex. Lichens, intestinal bacteria and humans, Clown fish and sea anemones.

Commensalism- one organism benefits and the other is unaffected. Ex. Cattle Egrets and cows.

Ecosystem Change

Ecological Succession

Ecological Succession

The changing of an ecosystems community of organisms over time as conditions within the ecosystem are altered by the original community.

Two types of Succession

Primary succession occurs in a place where organisms have not previously existed. Ex. Volcanic islands.

Secondary succession occurs in a place where organisms have already lived. Ex. Burned forest, abandoned farm.

Types of Communities

Pioneer community is the first set of organisms to inhabit an ecosystem. Ex. Lichens, mosses, grasses, insects, rodents.

Transition community is the organisms that succeed the pioneer organisms on the way to a stable climax community.

Climax community is the set of organisms that can survive in the mature, stable ecosystem. Ex. Trees, deer, bobcats, etc.

Energy in Ecosystems

Food Webs and Energy Pyramids

Habitat

The place where an organism lives.

NicheHow an organism makes its living.

Where it fits into an ecosystem. It’s chemical and physical needs.

Energy The ability to do work. Kinetic energy- energy of movement.

Examples: rock rolling downhill, a person running, a car rolling down the road.

Potential energy- stored energy.

Examples: a rock sitting at the top of a hill, food, gasoline.

SunThe original source of energy on

earth. Plants harness sunlight and turn it into food during photosynthesis.

Food WebTracks the movement of energy

through an ecosystem.

Trophic Levels

The feeding levels within a food chain or web.

ProducersMake their own food using sunlight

during photosynthesis.

Ex. Plants.

Primary ConsumersReceive their energy from

producers.

Ex. Rabbits, deer.

Secondary ConsumersReceive their energy from primary

consumers.

Ex. Snake.

Tertiary ConsumersReceive their energy from

secondary consumers.

Ex. Hawk.

DecomposersConsume organisms from each

level after death. Recycle nutrients. Ex. Bacteria.

Energy Pyramids

Show the transfer of energy between trophic levels.

10% Rule

90% of the energy captured by a trophic level is used and lost while 10% is available for use by the next level.

Matter in Ecosystems

Biogeochemical (Nutrient) Cycles

Matter

Anything that has mass and takes up space. Energy moves matter around.

Biogeochemical CyclesTrack the movement of nutrients through an ecosystem.

Nutrients

The building blocks of living matter.

Ex. Water, nitrogen, carbon, oxygen

Hydrological CycleTracks the movement of water

molecules through an ecosystem.

We interfere with this cycle by pumping water out of aquifers and off of surface water for irrigation and other uses. We also pollute water with our waste.

Importance of Water

Carries nutrients to the cells. Carries waste away from the cells. Is an ingredient of photosynthesis. Is an ingredient of decomposition. Is a coolant. Mixes with other substances to form

solutions.Ex. Blood, Kool Aid Is habitat for living organisms.

Nitrogen Cycle

Tracks the movement of nitrogen through an ecosystem.

Driven by bacterial fixation and decomposition.

Nitrogen is important to plant growth and forms part of DNA in all life.

We interfere with this cycle by mining nitrogen turning it into fertilizer which runs off into stream and lakes causing fish kills.

Carbon Cycle

Tracks the movement of carbon through ecosystems.

Is important because carbon forms many molecules that are found in living things.

Is driven by two processes: photosynthesis and cellular respiration.

We interfere with this cycle by burning fossil fuels which increases greenhouse gases causing global warming.