Science Man and His Environment/Ecology

Review

 * Environment : Everything that affects a living organism


 * Ecology : The branch of biology studying the relationships between living organisms and their environment

Abiotic/Biotic
We can divide the components of the environment into abiotic and biotic


 * Abiotic : non-living components


 * Biotic : living components

Abiotic components

 * sunlight
 * temperature
 * precipitation
 * wind
 * latitude
 * altitude
 * fire frequency
 * soil

In addition for aquatic organisms
 * water currents
 * dissolved nutrients
 * suspended solids

Species and Taxonomy

 * Organism : Any form of life


 * Species : Groups of organisms which can reproduce and produce fertile offspring


 * Genus (pl. genera) : Group of closely related species

Species names are given as Genus species. Both words are in italic, the first is always capitalized, the second is never capitalized.

Examples,
 * Felis catus - Domestic cat
 * Homo sapiens - Human

Higher groups with less closely related species (in order of most closely related to least related):
 * Family
 * Order
 * Class
 * Phylum

Example: Felis catus
 * Family: Felidae (all cats - including tigers, lions)
 * Order: Carnivores (carnivores)
 * Class: Mammalia (mammals)
 * Phylum: Chordata (chordates - includes all vertebrates)

Ecosystem Components

 * Population : group of organisms of the same species interacting within a geographical area


 * Community : All populations of different species within an area


 * Ecosystem : A community and their non-living environment


 * Biosphere : All of the Earth's ecosystems put together



Limiting factors
certain factors can be vital for the survival of a given organism. If these factors are present in too low or high a quantity then a species will not survive. These are called Limiting Factors

Habitat
A habitat is the place where a population lives

Niche
A niche (pronounced nitch) is the role which a species has within an ecosystem.

These niches can be from very broad to very narrow. Examples:
 * Broad niche - a cockroach


 * Narrow niche - giant panda -- feeds only on bamboo

Note that the habitat can be considered the address and the niche as the occupation.

Example 1: Giraffe versus Deer

 * Giraffe (with long neck) feed at the top of trees


 * Deer feed near the bottom of the tree


 * These are different niches

Example 2: Darwin's Finches

 * Darwin's finches are 14 species, each with a different niche


 * Some are seed eaters, while others eat insects.


 * Some are tree finches while others are ground finches


 * One has even adapted to the role of a woodpecker (using a cactus spine as a tool)

Food Chains
A food chain is a series of organisms each of which is a source of food for the next one




 * Trophic level : each level in a food chain

Major roles

 * Producers : Organisms which use energy to produce their own food


 * Consumers : Organisms which get their food by consuming other organisms


 * Primary consumers or Herbivores : Animal that eat producers


 * Secondary consumers or Carnivores : Animal that eat other consumers


 * Omnivores : Animals which are both herbivores and carnivores


 * Decomposers : Organisms which get their energy from dead organic matter

Food Web
The description of a food chain is too simplistic. Organism eat many other organisms. This leads to a further concept.


 * Food web : A food web is a set of interconnected food chains



Energy Flow
As energy is transferred through the food chain, the concept of energy flow applies.



The efficiency of each trophic level is about 5 - 20%. (10% is typical).

This means that carnivores have about 1% of the energy that plants capture.

The energy can be described in terms of biomass

This energy flow has an effect on the number of organisms at each level.