Ecology

ECOLOGY

I. VOCABULARY:

Ecology- The scientific study of interaction between organism and their environments.

I. VOCABULARY:

◦Environments:

Biotic factors –all the living organism that inhabit an environment

Environments:

Abiotic factors – the nonliving parts of the environment

Ex: air currents, temperature, moisture, light, and soil

I. VOCABULARY:

Population – is a group of organisms of one species that interbreed and live in the same place at the same time

◦Organisms compete for food, water, mates.

Determines how large each population can become

I. VOCABULARY:Ecosyste

m- The interacting system of a biological community and its nonliving environment.

I. VOCABULARY:Community – is a collection of

interacting populations

◦A change in one population in a community will cause changes in the other populations

I. VOCABULARY:

Habitat- Place where an organism lives;

◦Even in the same ecosystem, different organisms differ in their habitats.

II. SPECIES RELATIONSHIPS:

Producer- Organisms that produce their own food are called autotrophs.

Ex: Plants

all of the species of the ecosystem depend on autotrophs for nutrients and energy.

II. SPECIES RELATIONSHIPS:

Consumer- They obtain food by eating other organisms.

All the organisms that cannot make their own food (and need autotrophs) are called heterotrophs.

II. SPECIES RELATIONSHIPS:◦There are different levels of consumers:

Those that feed directly from producers, i.e. organisms that eat plant or plant products are called primary consumers.

Niche_= a role that an organism has in the environment (based on what they EAT!)

II. SPECIES RELATIONSHIPS:

1. Herbivores- consumer that eats only plants

◦Ex: grasshoppers, mice, rabbits, deer, beavers, moose, cows, sheep

II. SPECIES RELATIONSHIPS:

2. Carnivores- consumer that eats only other animals.

◦Ex: Foxes, frogs, snakes, hawks, and spiders.

II. SPECIES RELATIONSHIPS:

3. Scavengers – consumer that eats the remains of dead animals.

◦Ex: vultures, buzzards, crows, ants, beetles

II. SPECIES RELATIONSHIPS:

4. Omnivores- eats both plants (acting as primary consumers) and meat (acting as secondary or tertiary consumers).

◦Ex: Bears --They eat insects, fish, moose, elk, deer, sheep as well as honey, grass

II. SPECIES RELATIONSHIPS:

5. Decomposers- organisms that break down the remains of other organisms.

◦Found at the bottom of the food web.

◦Ex: Bacteria, yeast, fungi, worms and many insects

III. RELATIONSHIPS FOR SURVIVAL:

Symbiosis – permanent, close association between two or more organisms of different species

Symbiosis- 3 types:1. Commensalism – one species

benefits and the other species is neither harmed nor helped

◦Ex: an orchid growing on the branch of a larger plant

Symbiosis- 3 types:2. Mutualism – relationship that is

beneficial to both species

◦Ex: acacia trees (provides food/shelter for ants) and ants (protect tree by attacking any herbivore)

Symbiosis- 3 types:3. Parasitism – one species benefits

at the expense of the other species

◦Ex: ticks, tapeworms live on or in the organism

IV. MATTER & ENERGY IN ECOSYSTEMS:

Food Chain- Show one prey-predator relationship and how each living thing gets its food.

◦Some animals eat plants and some animals eat other animals.

◦Ex: Trees/shrubs giraffes lions

IV. MATTER & ENERGY IN ECOSYSTEMS:

Each link in this chain is food for the next link.

Always starts with plant life and ends with an animal.

IV. MATTER & ENERGY IN ECOSYSTEMS:

Trophic levels-link represented by each organism in a food chain;

◦Represents a feeding step in the transfer of energy and matter in an ecosystem.

IV. MATTER & ENERGY IN ECOSYSTEMS:

All energy in an ecosystem originates with the sun.

◦Plants transform solar energy into chemical energy (food) via photosynthesis

◦This is consumed by plant-eating animals, which are in turn consumed as food.

IV. MATTER & ENERGY IN ECOSYSTEMS:

The total energy transfer from one trophic level to the next is only about 10 %, the other 90% is lost as heat

IV. MATTER & ENERGY IN ECOSYSTEMS:

Heat is lost by:

1) Organisms fail to capture and eat ALL food available at the trophic level below them

2) Not all food that is captured and eaten gets digested

3) Digested food is used by the organism as a source of energy.

IV. MATTER & ENERGY IN ECOSYSTEMS:

Food web- model used to express feeding relationship among the members of a community.

◦A group of interlinked food chains

IV. MATTER & ENERGY IN ECOSYSTEMS:

Illustrates:

1. Who eats who?

2. Arrow = Energy flow through the community

3. Functional feeding groups

4. Important ecological interactions

Identify a primary producer

Identify a primary consumer

Identify a secondary consumer

Identify a tertiary consumer

Identify a Quaternary Consumer

Identify a decomposer

V. Differences between a food web & food chain:

1) Food chains ONLY show one prey-predator relationship. The source of food is also often seasonal with many animals adapting to changes in the season by eating different types of food.

2)  Food webs show a better picture of interrelationships between plants and animals.

VI. How Pollution Can Affect Organism:

Biomagnification = The process of increasing a chemical concentration through the food chain (Examples: DDT and PCB)

◦Animals that eat other animals have HIGHER levels of contaminants than animals that eat plants. 

◦Some contaminants are persistent - once they are in the animal's body, they stay there for a long time. 

Biomagnification:

So when smaller animals are eaten by bigger animals, all the contaminants stored in their tissues are then passed on to the bigger animal.

The result of biomagnification is that animals at the "top" of their food chain have higher contaminant levels than animals at the "bottom".

Biomagnification:The top predators at the end of a long

food chain may accumulate concentrations of a toxic chemical high enough to cause serious deformities or death even though the concentration of the chemical in the open water is extremely low.

◦The concentration of some chemicals in the fatty tissues of top predators can be millions of times higher than the concentration in the open water.

Ex: Mercury, DDT, PCB’s, arsenic

Nutrient

Cycles

Water Cycle

1. Water cycles between the oceans, atmosphere and land.

A. Water enters the atmosphere as water vapor, a gas, when water evaporates from the ocean or other bodies of water.

◦Evaporation—the process by which water changes from a liquid to a gas.

Water CycleB. Water can also enter the atmosphere by evaporating from the leaves of plants—Transpiration.

Water Cycle

C. Precipitation--rain, snow, sleet, or hail

◦The sun heats the atmosphere.

◦Warm, moist air rises and cools.

◦Eventually, the water vapor condenses into tiny droplets that form clouds.

◦When the droplets become large enough, the water return to Earth’s surface.

Water Cycle

D. Run-off—Precipitation runs along the surface of the ground until it enters a river or a stream that carries the run-off back to an ocean or lake.

E. Seepage—Rain also seeps into the soil, some of it deeply enough to become ground water. Water in the soil enters plants through the roots, and the water cycle begins anew.

Water Cycle

Precipitation

EvaporationTranspiration

Condensation Condensation

SeepageSurface Run-off

Ground Water

Precipitation

Carbon Cycle

1. Every organic molecule contains the element carbon.

A. Carbon and oxygen form carbon dioxide gas (CO2), an important component of the atmosphere.

Carbon CycleB. Carbon dioxide is taken in by plants during photosynthesis and is given off by plants and animals during cellular respiration.

◦Cellular respiration is a process where cells transform chemical energy (sugar) into a useable form of energy (ATP).

Carbon Cycle

2. Four main types of processes move carbon through its cycle:

Biological processes, such as photosynthesis, cellular respiration, and decomposition, take up and release carbon and oxygen.

Geochemical processes, such as erosion and volcanic activity, release carbon dioxide into the atmosphere and oceans.

Carbon CycleMixed biogeochemical processes, such as the

burial and decomposition of dead organisms and their conversion under pressure into coal and petroleum (fossil fuels), store carbon underground.

Human activities, such as mining, cutting and burning forests, and burning fossil fuels (car emissions, electricity), release carbon dioxide into the atmosphere.

Carbon Cycle

Burning of Fossil Fuels Cellular

Respiration

CO2 in atmosphere

Photosynthesis

Coal & Petroleum

Decomposition of dead organisms

Nitrogen Cycle1. All organisms require nitrogen to make amino acids, which in turn are used to build proteins.

A. Nitrogen gas makes up 78% of Earth’s atmosphere.

Nitrogen Cycle

B. Nitrogen containing substances such as ammonia (NH3), nitrites (NO2

-), and nitrates (NO3

-) are found in the wastes produced by many organisms and in dead and decaying organic matter

C. Nitrate is major component of plant fertilizers.

Nitrogen Cycle2. Nitrogen gas is the most abundant form but only certain bacteria can use this form.

A. Such bacteria live in the soil and on the roots of plants.

B. These bacteria convert nitrogen gas into ammonium--nitrogen fixation

C. Other bacteria in the soil convert ammonia into nitrites and nitrates.

Nitrogen Cycle

3. Once the nitrites and nitrates are available, producers (plants) can use them to make proteins.

◦Consumers then eat the producers and reuse the nitrogen to make their own proteins.

4. When organisms die, decomposers return nitrogen to the soil as ammonia.5. Other soil bacteria convert nitrates into nitrogen gas--denitrification. This process releases nitrogen into the atmosphere once again.

Nitrogen Cycle

Nitrogen Decomposers

return ammonia to soil

Denitrification

Nitrates

(NO3-)

Nitrites(NO2

-)

Nitrogen in atmosphere (N2)

VIII. A Change in Communities OVER Time: SUCCESSION

Succession = orderly, natural changes that take place in the communities of an ecosystem

◦The community of organisms inhabiting an area gradually changes.

◦Difficult to observe since it can take decade or centuries for one type of community to completely succeed another.

Figure 1: Succession of plant species on abandoned fields in North Carolina. Pioneer species consist of a variety of annual plants. This successional stage is then followed by communities of perennials and grasses, shrubs, softwood trees and shrubs, and finally hardwood trees and shrubs. This succession takes about 120 years to go from the pioneer stage to the climax community.

Primary Succession Primary succession =establishment of a

community in an area of exposed rock that does not have any topsoil.

◦Ex: Lava flowing from a volcano destroys everything in its path, but when it cools it forms new land

Primary Succession◦Ex: Streams gradually deposit silt along their banks, creating new soil in which plants can take root.

Primary Succession◦After some time, primary succession slows down, and the community becomes fairly stable.

A stable, mature community that undergoes little of NO succession is called a climax community.

Secondary Succession:Secondary succession = the sequence

of community changes that takes place when a community is disrupted by natural disasters or human actions

Ex: Hurricanes, forest fires, farmers abandoning fields

BIOMES

IX. BiomesBiomes = a large group of

ecosystems that share the same type of climax community

Two factors that will determine which biome will be dominant on land:

1. Temperature

2. Precipitation

What do you think the Tundra would look like?

1. TundraCharacteristics: treeless, long cold winters,

little winter sun, poor soil, little rain (less than 5 in)

Permafrost – permanently frozen ground

Location: Canada, Russia, Alaska

Vegetation: grasses, moss, lichen

TundraAnimals: insects, fox, rodents,

caribou, reindeer

What do you think the tiaga looks like?

2. TaigaCharacteristics: coniferous forest, poor soil, long

severe winter

Location: Canada, N. Europe, N. Asia

Vegetation: pine, fir, hemlock, spruce

Animals: rabbits, lynx, caribou, moose, woodpecker

What do you think a temperate forest looks

like?

3. Temperate Forest (where we live!)

Characteristics: deciduous trees, 4 seasons, vegetation exhibits seasonal changes

◦Deciduous – trees lose leaves in winter

Location: East US, Europe

Vegetation: Maple, Oak, Birch, Hickory

3. Temperate Forest (where we live!)

Animals: bear, deer, robin, raccoon

What do you think a tropical rain forest would look like?

4. Tropical Rain ForestCharacteristics: warm, wet,

humid, most diversity, up to 17 feet of rainfall annually

Location: islands, equatorial regions

Vegetation: broad lush plants, flowers, vines, palms, fruit trees

◦lush with many layers in the canopy that support an incredible diversity of life.

4. Tropical Rain ForestAnimals: monkey, sloth, frogs,

snakes, parrots

What do you think a grassland would look

like?

5. GrasslandCharacteristics: ideal growing

season, good soil quality, little precipitation does not support trees, but grasses and herbs are present in great abundance.

5. Grassland Location: central regions

Types:

◦ Prairie – US

◦ Steppe – Russia

◦ Savanna – Serengeti

◦ Pampas - Argentina

5. GrasslandVegetation: grass, grains, crops,

wildflowers

Animals: bison, prairie dogs, birds, lions, elephants

What do you think a desert would look like?

6. DesertCharacteristics: dry & arid, less than 10 in

of rainfall

Location: SW US, N. Africa, Middle East

◦Hot- Mojave, Sahara

◦Cold- Gobi

6. DesertVegetation: Plant cover is sparse,

and characterized by drought tolerant brushes, succulent (cacti, creosote bushes)

6. DesertAnimals: rodents(gerbils,

jerboas and kangaroo rats), snakes, lizards, scorpions, turtles, hawks

Population

Dynamics

X. Population DynamicsAll species occur in groups called

populations

Limiting factors = factors that are biotic or abiotic that keep a population from continuing to increase indefinitely

X. Population Dynamics 2 types of Population-Limiting

Factors:

• density-independent factors

• density-dependent factors

X. Population Dynamics

Density-independent factors = Any factor in the environment that does not depend on the number of members in a population per unit area

Usually abiotic (natural phenomena)

Ex:

Weather events (tornadoes, floods, hurricanes)

Fire

Human alterations of the landscape

Air, land, and water pollution

X. Population DynamicsDensity-dependent factor = Any factor in

the environment that depends on the number of members in a population per unit area

Usually biotic

Ex:

◦Predation

◦Disease- (high population density--> disease quickly spreads)

◦Parasites

◦Competition – food, space limitations

X. Population DynamicsThe population growth rate (PGR)

explains how fast a given population grows.

X. Population DynamicsExponential

growth occurs when the growth rate is proportional to the size of the population.

All populations grow exponentially until some limiting factor slows the population’s growth.

X. Population DynamicsThe population’s growth slows or

stops following exponential growth, at the population’s carrying capacity.

X. Population DynamicsA population stops increasing when

the number of births is less than the number of deaths or when emigration exceeds immigration.

X. Population DynamicsCarrying capacity = The

maximum number of individuals in a species that an environment can support for the long term.

◦limited by the energy, water, oxygen, and nutrients available.

◦Population exceeds carrying capacity- deaths outnumber births because resources are not available to support all individuals

X. Population Dynamics

If the major food source of seals declines due to pollution or overfishing, which of the following would likely occur?

a) The carrying capacity of seals would decrease, as would the seal population.

b) The carrying capacity of seals would decrease, but the seal population would remain the same.

c) The number of seal deaths would increase, but the number of births would also increase, so the population size would remain the same.

d) The carrying capacity of seals would remain the same, but the population of seals would decrease.