POPULATIONS & COMMUNITIES
Populations and communities prezi
Prezi Transcript
Living things are called Organisms
Review
Living Things Need:
Food
Water
Shelter
Air
Homeostasis
Ecology: The study of how living things interact with one another
and their environment
Habitats
An environment that provides for the needs of a living organism
Abiotic Factors: Nonliving things
Biotic Factors: Living things
Abiotic Factors
Water
Needed by most organisms to carry out life processes
Sunlight: Needed for Photosynthesis
Oxygen: Needed for life processes
Temperature: Determines species (Some animals can't live in hot/cold environments)
Soil: Influences plants---also influences animals since they need plants for food
Organization
Organism: One single thing
Population: All members of a species in a given area
Species: A group of organisms that are physically similar and can mate to produce offspring
Community: A combination of populations in an area
Ecosystem: Community plus abiotic factors in an area
Determining Size Of Population
Direct Observation: Count what you see
Indirect Observation: Look at signs but you don't see the animal
Sampling: Estimating (Getting an approximate number) based on assumption
Ex. I see 10 deer on 1 acre..I assume there will be 100 deer in the 10 acres
Mark and recapture studies: Capture and tag the species. They use this to estimate reproduction rate
New animals will not be tagged
Changes in Population
Birth/Death Rates
Birth Rate: How many animals are born into the population
Death Rate: How many animals die and leave the population
If birth rate is larger than death rate: Population increases
If birth rate is smaller than death rate: Population decreases
Immigration/Emigration
Immigration: Animals coming into a population
Emigration: Animals leaving a population--moving out
Population Density
Remember: Density is the amount of matter in a space...SOOOOO.
Population Densityis the number of organisms in a space.
Formula: # Individuals/Unit of area
Density-Dependant factors: Competition, disease & Predation that only become limited when the
population gets to a certain size.
Usually only affect large, dense populations
Density-Independent factors: Affect all individuals regardless of size or density
Unusual weather, natural disasters, seasons, human affects on the environment
Limiting Factors
A factor that causes the population to decrease
Carrying Capacity: The largest population an area can support. (How much it can carry)
Food & Water
: If either is in low supply, organisms will emigrate to find supplies elsewhere
Space
: If organisms don’t have the basic shelter and space needed for survival, they may be killed or may
move to find the space they need.
Weathe
r: Unusual temperature changes, storms, or floods can change available living space and kill animals in
an area.
These events can drastically change the biotic factors in an area.