the study of the interactions between organisms and their environments
nonliving chemical and physical factors. EX. sunlight, air, minerals, water, wind, temp, rocks, soil.
two components (parts) of the environment
abiotic and biotic
living factors in the environment EX. autotrophs/producers and heterotrophs/consumers
organisms that make their own food
organisms that cannot make their own food & must obtain them by consuming other organisms or products.
only eat plants
only eat other animals
eat both plants and animals
breakdown dead or organic matter
any living thing EX. deer
a group of the same species living together in the same area EX. heard of deer
groups of different organisms living together in the same area EX. squirrels, birds, chipmunks, foxes, etc.
all biotic & abiotic factors in an area EX. forests, woods
an area with its own particular climate & life EX. temperate forest
all biotic & abiotic portions of the Earth that sustain life EX. Earth
mark & recapture
used to make multiple counts in an area, good for populations that move; results are going to be a little lower than actual population
used to make a one-time count of multiple areas, good for large populations that don't move.
Why study populations?
Help conserve species & biodiversity, improve health care & control outbreaks, maintain sustainable harvests, assist with urban & economic planning.
refers to the number individuals in a population/area or volume EX. # of oak trees in a forest, # of ants per cubic meter of soil
Scientists can estimate population density using 2 different sampling techniques
mark & recapture, and random sampling
refers to the way individual's are spaced within the habitat.
results from unequal distribution of resources (water or soil), mating or social behavior, or predator avoidance; most common type in nature. EX. pride of lions, school of fish, flock of birds
results from interactions among individuals in the populations; equal distance away from each other. EX. penguin nests
results from the absence of interactions or environmental pressures; individuals are spaced in a patternless, unpredictable way. EX. forest trees
the change in the size of a population over time
the two types of growth
exponential growth and logistic growth
the population size increases by a constant factor; results from ideal conditions with no regulations; generally short-lived in nature due to limiting factors; produces J-curve graph. EX. bacterial growth
ideal growth that is slowed by limiting factors; predicts slow growth when the population is small or large & fast growth when populations are of intermediate size; growth occurs until it hits the carrying capacity; produces an S-curve graph. EX. Humans
the # of individuals in a population that the environment can maintain with no net increase or decrease, caused by limiting factors.
environmental factors that restrict population growth; 2 types DD and DI
density dependent factors
factors that limit the population only when it reaches a certain size or density; factors effect a greater % of individuals as the # of individuals increases. EX. competition for resources, predators, pollution, parasitism, and disease.
density independent factors
factors that limit a population regardless of the size or density; a factor's effect is unrelated to population size. EX. natural disasters, changes in abiotic factors (light, temp, weather), and human development
boom & bust
rapid increase in a population followed by rapid decrease; related to predation and fluctuation in food supply. EX. snowshoe hare & lynx populations go through a 10-year cycle.
the # or % of people in each age group
age structure pyramid
a graph in which horizontal bars represent the percentage of the population in each age group; male on left, females on right.
factors affecting human population growth (besides normal birth & death rates)
# offspring/birth, age of reproduction/maturity, carrying capacity & technology.