Ecology
study of the relationships among organisms and the environment.
population
consists of interbreeding organisms of one species occupying the same area at the same time.
community
includes all populations, representing multiple species, in the same region.
ecosystem
is the biotic, or living, community plus the abiotic, or nonliving, environment
biosphere
all parts of the planet where life exists
habitat
the physical location where the members of a population live.
Population density
number of individuals of a species per unit area or unit volume of a habitat.
Population distribution
describes how individuals are scattered through the habitat. •Uniform •Clumped •Random
Subpopulations
separate a population, If separated for a long period of time, subpopulations may become new species.
Birth rate
number of individuals produced per unit of time.
Immigration
movement of individuals into a population
Death rate
the number of deaths per unit of time
Emigration
movement of individuals out of a population.
Survivorship curves
show the proportion of surviving individuals at each age.
Life tables
group of individuals within a population from birth to death. In the accompanying survivorship curve
type I survivorship curve
representative of species that invest much energy caring for young and have low death rates early in life. Most individuals survive to reproduce.
Type II survivorship curve
have an approximately equal probability of dying at any age.
Type III survivorship curve
representative of species that invest little energy raising their young and have high death rates among offspring. Few individuals survive to reproductive age.
population growth formula
G=rN
G is the growth rate
r is the per capita rate of increase
N is the initial size of the population
Exponential growth
when its growing / death rate increases over a given time period ( J-shaped curve)
Environmental resistance
combination of factors that keeps a population from reaching its maximum growth rate. (ase as population size increases due to competition, predation)
carrying capacity
which is the maximum number of individuals that the ecosystem can support indefinitely
logistic
population size approaches the carrying capacity, the growth rate slows (s curve)
logistic growth equation
G=rN((K-N)/K)
G is the growth rate
r is the per capita rate of increase
N is the initial population size
K is the carrying capacity
Density-dependent factors
result from interactions between organisms
Density-independent factors
effects that are unrelated to population density.
Life history
all of the events of an organism's life from conception through death.
opportunistic life history
short-lived, reproduce at an early age, and have many offspring that receive little care.
equilibrium life history
tend to be long-lived, mature late, and receive extended parental care.