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Ecology - PowerPoint PPT Presentation

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Ecology. Ecology. Ecology is the study of the relationships between living things and their interactions with the physical environment. All life is found in a thin band that surrounds the planet called the Biosphere .

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Ecology is the study of the relationships between living things and their interactions with the physical environment.

the biosphere
The Biosphere

Biosphere is made of biotic factors (living)


The biosphere is broken up into regions based on climate, & the resulting organisms.


The ecosystems are regions inside biomes that have the same climate.

Ecosystems in different areas of Earth may have different organisms.


Are all the living things that are found in an ecosystem.

A forest community would have trees, deer, birds, bacteria, etc


All the creatures that are found in the same area and have the potential to reproduce together is considered a population

Deer pop., tick pop., Pine tree pop.






individual of a species

niche and habitat
Niche and Habitat
  • In the ecosystem, each species has a niche and a habitat.
  • The habitat is where it lives, e.g. top of tree, open ocean, grasslands
habitat and niche
Habitat and Niche

An organism’s niche is what it does in that habitat (its lifestyle)

e.g. eats a specific type of seed on a bush, hunts a specific prey

No more than one species can occupy a specific niche or there will be competition, and all but one species will ultimately die off.
food webs
Food Webs

The main relationship between organisms is based on energy

Organisms are placed into levels based on how they get their energy.

trophic levels
Trophic Levels

The levels that organisms are placed into are called trophic levels (feeding levels).

Producers- organisms that convert sunlight into chemical energy (glucose)

trophic levels1
Trophic Levels

Consumers- organisms that must eat other things for energy

Herbivores- (primary consumers) eats only plants or producers

trophic levels2
Trophic Levels

Carnivores- (secondary consumers) eats only other consumers

Ominvores- eats both producers and consumers

trophic levels3
Trophic Levels

Decomposers- breaks down large molecules into smaller ones to be reused by producers.

E.g. bacteria and fungi

The flow of energy from one creature to another is a food chain.
  • Krill eats some algae, a cod eats the krill, a seal eats the cod, orca eats seal.





energy pyramids
Energy Pyramids
  • Organisms are unable to utilize all the energy they consume.
  • Much of the energy is lost as heat.
Only 10% of the energy at one trophic level can be used by animals at the next trophic level.
  • The result is that there must be many more producers than herbivores & more herbivores than carnivores.

Because of the loss of energy at each trophic level, there is usually a larger mass of living tissue at the lower levels than at the upper levels.

biomass pyramid
BioMass Pyramid

Secondary Carnivore

Primary carnivore



nutrient cycles
Nutrient Cycles
  • Energy is not the only thing moved from one organism to another.
  • Nutrients (nitrogen, carbon, oxygen, water) are also cycled through the ecosystem
nitrogen cycle
Nitrogen Cycle
  • Nitrogen gas (N2) is naturally found in the atmosphere.
  • N2 is unusable to most living things.
Some bacteria are able to change nitrogen gas into chemicals called nitrates, which are usable by plants.
  • The process of making nitrates is called nitrogen fixation
Plants use nitrates to make amino acids and proteins.
  • These proteins are then passed through the food web.
When an organism dies or gives off waste, the nitrogen trapped is changed back into nitrates or nitrogen gas by decomposing bacteria.
  • This process is called denitrification
carbon cycle
Carbon Cycle
  • Carbon is found in the atmosphere as Carbon Dioxide (CO2)
  • CO2 is used by plants during photosynthesis to build carbohydrates.
Animals eat carbohydrates for energy
  • During cellular respiration, the carbohydrates are changed into ATP and CO2.
  • The organism must then release the CO2 back into the atmosphere.
Some carbon is trapped in dead creatures and changed into a fossil fuel (coal or oil).
  • When these are burned, the carbon is released as CO2 .

Symbiosis is a relationship between any two living things.

There are four main types of relationships.

The caterpillars have nectar organs which the ants drink from, and the acacia tolerates the feeding caterpillars. The ants appear to provide some protection for both plant and caterpillar.
The senita cactus, whose flowers bloom only after dark and are pollinated almost exclusively by this senita moth. The moth lays its eggs (top right) in flowers. Larvae (moth caterpillars) which hatch from these eggs later consume some of the fruits.
population ecology
Population Ecology

The relationships between populations have an effect on their size and success.

There are many factors that help to determine the size of a population

population change
Population Change

There are two things that cause the population to grow:

Births and immigration (individuals entering the population from another population)

Two things cause the population to decline:

Death and emigration (individuals leaving the population)

Under ideal conditions, a population will grow at an exponential rate, the larger it gets, the faster it grows

Exponential Growth Curve

In natural conditions, exponential grown does not last long.

Limiting factors will control how large a population can grow.

limiting factors
Limiting Factors

Limiting factors come in two forms

  • Density-dependent
  • Density- independent

The larger the population, the greater the effect. (food, water, space, disease, mates, predators)


Population size has no effect (natural disaster, climate, temperature)

carrying capacity
Carrying Capacity

If a population has sufficient resources, it will grow at an exponential rate.

There will be many births and few deaths

carrying capacity1
Carrying Capacity

Eventually the population reaches the limit the environment can support. Limiting factors cause more deaths (starvation, disease, malnutrition)

The natural limit the environment can support is called the carrying capacity.

Logistical Growth Curve

human population
Human Population

Currently, the human population is growing at an exponential rate.

With more people on the planet, we require more resources to keep us alive and produce more waste with our activities.
Most ecological problems are caused by human activities.

Habitat destruction, pollution, greenhouse effect, ozone depletion, and endangered species