Download 4.2 What shapes an Ecosystem? Key Concepts How do biotic and

4.2 What shapes an Ecosystem?
Key Concepts
How do biotic and abiotic factors influence an ecosystem?
What interactions occur within communities?
What is ecological succession?
Biotic Factors
all living things in an ecosystem
example - all animals and plants
Abiotic Factors
physical, or nonliving things in an ecosystem
example - temperature, rain, humidity, wind, soil, rocks, sun
Removing biotic elements can dramatically affect the ecosystem's abiotic conditions.
Example - Trees in forest hold topsoil with their roots, shade the
soil, contribute organic matter to the soil in the form of
dead leaves, and return water to the atmosphere
through evaporation and transpiration. Removing trees
from the forest ecosystem reduces these benefits.
Niche
physical and biological conditions in which or organism lives and the way in which the
organism uses these conditions
type of food
how it gets its food
what is its predator
Community Interactions
Resource
any necessity of life
water, food, light, nutrients
Competition
 
*occurs when two or more organisms of the same
 
or different species attempt to use the same limited resource
 
examples: pollinators, sunlight, animals
Predation
 
*one organism kills and eats another organism
 
 
prey -- organism that is eaten
predator -- organism that does the killing and eating
 Several principles of predation
 
1. predators are usually beneficial organisms
 
2. predators prey on surplus animals and do
not cause a serious decline in the prey population
 
3. predators do not cause extinction
 
4. predators will control population
Wolves - top predator in its ecosystem. Wolves were once hunted until they were considered
endangered. The populations of deer and other herbivores increased dramatically. As these
populations overgrazed the vegetation, many plant species that could not tolerate such
grazing pressure disappeared from the ecosystem. In turn, many insects and small animals
that depended on the plants for food also disappeared. The elimination of wolves thus
produced an ecosystem with considerably less species diversity.
How does human activity affect the patterns of predation?
Symbiosis
two species live closely together
Classes of Symbiosis
 
Mutualism
*relationship between two species in which both benefit
 
 
 
 
 
example: ant/blue butterfly
ant protects larvae from predators, larvae secrete sugar
solution for the ants
Commensalism
*relationship in which one species benefits and the
other is neither harmed nor helped
 
examples: remoras/sharks, flowers that grow in trees
Parasitism
 *relationship between a host and a parasite
 
 
 
host -- organism that gives the parasite nourishment
parasite -- organism that lives in or on another
organism without immediately killing it
woodtick, tapeworm
Would a giraffe be a parasite eating leaves? Why or why not?
Lab - Competition Lab
Life Video - Fish
Fox Lab