Download Ecology – study of relationships between organisms and between

ECOLOGY – study of relationships between organisms and between organisms and their physical
environment.
ECOLOGICAL ORGANIZATION –
1. Population – all members of a species living in a given location
2. Community – all the interacting populations in a given location
3. Ecosystem – all members of a community plus the physical environment in which they live
(living and non-living)
4. Biosphere – portion of earth in which living things exist; composed of many complex
ecosystems, including H2O, soil, and air.
ABIOTIC FACTORS OF ECOSYSTEMS – “abiotic” = non-living
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intensity of light
temperature range
amount of H2O
soil type
availability of minerals and other inorganic substances
supply of gases (O2, CO2, N2)
pH (how basic or acidic a substance is)
Abiotic factors determine types of plants and animals that can exist in an area.
Abiotic factors = “Limiting Factors”
Example – amount of H2O limits kinds of plants and animals in a desert
BIOTIC FACTORS – “biotic” = living plants and animals
Biotic factors interact in 2 ways:
1. Nutritional Relationships: transfer of nutrients
 Autotroph – makes own food (photosynthesis)
 Heterotroph – obtains food from environment
4 Categories of heterotrophs –
* Saprophyte – obtain nutrients from remains of other plants (mushrooms feed on
dead plants and animals)
* Herbivores – feed on plants
* Carnivores – feed on other animals
Predator – kill and consume prey
Scavenger – feed on remains of animals they do not kill
* Omnivore – feeds on plant and animal
2. Symbiotic Relationships: different organisms living together in a close association
 Commensalism – one organism benefits and the other is not negatively affected
*Barnacles living on whales
 Mutualism – both organisms benefit
*Protozoan lives in digestive tract of termite. Wood that is eaten is digested by
protozoan so termite can eat more
 Parasitism – one organism benefits and the other is harmed
*Tapeworm in a dog
ENERGY RELATIONSHIPS:
1. Food Chain – transfer of energy from green plants through a series of organisms with
repeated stages of eating and being eaten
1. Producers – green plants and other autotrophs
2. Consumers – all heterotrophic organisms
 Primary consumer – animal that eats green plants
 Secondary consumer – animal that feeds on primary consumer
(carnivore)
 Omnivore – a primary or secondary consumer
3. Decomposers (bacteria or fungi) – break down dead organisms
2. Food Web – combination of food chains
3. Energy Pyramid – shows loss of usable energy in a community
CYCLES OF MATERIALS:
1. Carbon-Hydrogen-Oxygen Cycle – recycled through respiration and photosynthesis
2. H2O Cycle
3. Nitrogen Cycle – nitrogen is important because it is part of the structure of amino acids and
proteins
ECOSYSTEM FORMATION: both abiotic and biotic parts change over time
Succession – replacement of one kind of community by another (depends on climate)
*Pioneer Organisms – 1st plants to populate a given area
*Modifications – starting with pioneers, each community modifies the environment
making it less favorable for itself and more favorable for others
Example in NY: lichens, grasses, shrubs, conifers (pine), deciduous woodland (beech
and maple)
*** These modifications also change the animal populations. ***
Climax Communities – end of succession in which populations of plants and animals exist in balance
with each other and the environment.
 climax comm.. remains stable until a catastrophe; succession will begin again.
Example in NY: Oak/Hickory and Hemlock/Beech/Maple association are stable
Niche – specific role a species has, including its type of food or nutrients it requires, where it lives,
where it reproduces, and its relationships with other species.
* Competition for the same niche results in eliminating the weaker species
BIOMES
Biome – the type of climax ecosystem that develops in large climatic areas; can be terrestrial or
aquatic
Terrestrial biomes – determined by
*latitude– at equator, temp and rainfall are constant; varies toward the poles
*altitude – increasing altitude affects vegetation
*water, mountains, deserts
Aquatic Biomes – largest ecosystem on earth
1. Marine Biome – saltwater
 most stable environment on earth
 absorbs/hold large quantities of solar heat, stabilizing temp
 constant supply of nutrients and dissolved salts
 most photosynthesis occurs in oceans along edges of land
2. Freshwater Biome – ponds, lakes, rivers
 vary in size, temp, O2, CO2, current velocity, rate of succession, murkiness
 in all but the largest lakes, there is succession from freshwater to terrestrial biome:
 Dead plants accumulate on bottom and around banks
 The body of water will become smaller and shallower