4-2 What Shapes an Ecosystem? A. Ecosystem conditions: 1. Biotic factorsbiological influences on organisms within an ecosystem. a. Examples: plants, bacteria, and animals.
2. Abiotic factors- nonliving or physical factors that effect the ecosystem a. Examples: temperature, precipitation, wind, soil type and sunlight.
3. habitat- the area were an organism lives, it includes both biotic and abiotic factors.
4. niche- the job of an organism, it too includes biotic and abiotic factors, the full range of conditions in which an organism lives and the way in which the organism uses those conditions.
B. Community interactions: 1. competition- when organisms of the same or different species attempt to use an ecological resource in the same way at the same time. There is usually a winner and a loser that does not survive.
a. resource- anything that is needed to survive
b. competitive exclusion principle- states that no two species can occupy the same niche in the same habitat at the same time. Blue Warbler Feeds at the tips of branches near the top of the tree Bay-Breasted Warbler Feeds in the middle part of the tree Spruce tree X Cape May Warbler Feeds at the tips of branches near the top of the tree Yellow-Rumped Warbler Feeds in the lower part of the tree and at the bases of the middle branches
2. Predation- an interaction in which one organism captures and feeds on another organism.
a. Predator- the animal that captures and feeds on another animal b. Prey- the animal that is hunted and eaten by a predator
3. Symbiosis- a relationship in which two species live closely together 3 types
a. Mutualism- both species benefit from the symbiotic relationship.
1) Example: a) flowers and bees: the flower benefits by being pollinated and the bees benefits by getting food (nectar and pollen)
b) termite and the flagellate; the termite get nutrients from the wood that the flagellate digests and the flagellate gets a home and is feed by the termite.
c) Ants and aphids
d) algae and fungus living together form a lichen
b. Commensalism- one member of the relationship benefits and the other is nether helped nor harmed.
1) Examples: a) barnacles attached to a whale s skin: whale is not hurt or helped by the barnacles, barnacles benefit from the constant movement of the water which carries food particles.
b) A remora (a small fish with a suction disk on the top of its head) hitches a ride with a large sea animal such as a sea turtle or a shark. This benefits the remora by being taken to its next meal without having to spend energy to swim and hunt. The shark or turtle isn t hurt but doesn t benefit either.
c) Orchids and trees
d) Lichen and trees
e) Hermit crabs and other mollusk s shells
c. Parasitism- one organism lives on or inside another organism and harms it. The organism that benefits is called the parasite, the other organism is called the host. Usually the parasite weakens, not kills, the host.
1) Examples: a) tapeworms that live inside their host organism.
b) Fleas, ticks, lice, leeches, flukes and even mosquitoes living on mammals for their skin and blood.
c) Some molds (water molds on fish), some fungi (athletics foot, ringworm, tree fungi) are parasites.
C. Ecological Succession 1. ecosystems are constantly changing.
a. in response to natural changes
b. and human disturbances
2. ecosystems go through a predictable series of changes. a. Older inhabitants die out and b. new organisms move in producing additional changes. 3. ecosystems change a. slowly as changes occur over time or b. quickly in response to disasters
4. Succession a. Primary succession- succession that occurs on surfaces where no soil exists. The surface is rock or ash, typical of a volcanic area.
1) The first organisms to grow in the area are called pioneer species. a) Lichens- these organisms actually help to break down the rock with enzymes from their rhizoids. This broken rock is the beginning of soil. As soil is produced the surface begins to change other plants will now be able to live in the area.
Mosses on rock Lichens on rock Grasses and other plants growing in thin layer of soil over rock layers
b. Secondary succession- occurs when a disturbance of some kind changes the community without removing the soil. This often occurs after a plot of farmland has been abandoned and begins to grow wild.
After a forest fire, the forest will start to re-grow.
Mt. Saint Helen s forest at 3 month, 9 years, and 14 years after the 1980 volcanic eruption.
Climax community- As areas proceed through the stages of succession, eventually a mature, stable group of organisms populate the area. This community seems stable and maintains itself over a long period of time. However, the environment is constantly changing and even the climax community changes in response to subtle changes through time.