population
a collection of individuals of all one species living in a specific area
community
a collection of several populations interacting with one another in a particular location
population density
the number of organisms of a population living in a specified area;
affected by birth rate, death rate and immigration and emigration
exponential growth
there is plenty of food and space and a population grows rapidly,
DOUBLING every generation
equilibrium
stability, equal balance between any powers, influences, etc.
carrying capacity
the largest population that an ecosystem can support
Three factors that affect the size (density) of a population
1. Birth rate
2. Death rate
3. Immigration and Emigration
population growth occurs when
occurs when there is an abundant amount of food, space, and resources with few or no predators
logistic growth
Factors that cause population growth to decrease: 1. competition 2. predation
3. parasitism 4. disease
Two types of logistic growth:
1) density-dependent factors
2) density-independent factors
competition
when the population becomes crowded, organisms compete with one another for food, water, space, sunlight etc.
predation
when one animal hunts another animal;
predators often control population growth
density-independent factors
affect a population regardless of density (numbers or size)
includes: weather, natural disasters, and certain human activities
density-dependent factors
factors that affect crowded populations more than uncrowded ones;
spread of disease, competition for food, water space, and sunlight
Food Chain
A series of steps in which organisms transfer energy by eating and being eaten
Food Web
A network of many food chains
consumer
any organism that must consume (eat) other organisms to get energy
primary producer
organisms that make their own food from sunlight or chemical energy
primary consumer
organisms that get their energy by eating primary producers (herbivores)
herbivores
organisms that eat only plants
secondary consumer
organisms that get energy by eating the primary consumers and/or primary producers
(carnivores or omnivores)
tertiary consumers
organisms that get energy by eating secondary consumers (carnivores)
(tertiary = third)
tertiary
third
omnivore
eats both plants and animals
carnivore
only eats meat
food chains always begin with
producers / autotrophs (make their own energy using sunlight)
autotrophs
organisms who use photosynthesis or chemosynthesis as a source of energy, (most plants and certain bacteria and protists)
heterotrophs
organisms who cannot make there own food
arrows in a food chain show the flow of
energy
ecological pyramid
represents how food and energy are transferred from each feeding level to another
biomass pyramid
shows the mass of consumer tissue supported by each level below it
numbers pyramid
shows the total numbers of individuals in an ecosystem at each level during one year
energy pyramid
shows the transfer of energy from one level to another in a food chain