is a group of individuals of a single species that occupy the same general area
the factors that influence a population's density, structure, size growth rate.
Population ecology focuses on
is the number of individuals of a species per unit of area or volume.
Population density
of a population is the distribution of individuals in different age-groups.
age structure
largemouth bass per cubic kilometer (km3) of a lake, oak trees per square kilometer (km2) in a forest, and nematodes per cubic meter (m3) in a forest's soil
Examples of population density
track survivorship (the chance of an individual in a given population surviving to various ages) help to determine the most vulnerable stages of the life cycle
Life tables
the history of a population's survival, reproductive success, and/or how the population relates to environmental factors
The age structure of a population provides insight into
plot the number of individuals still alive at each age in the maximum life span are classified based upon the rate of mortality over the life span of an organism
Survivorship curves
take immediate advantage of favorable conditions and typically exhibit a type III survivorship curve
Organisms with an opportunistic life history
develop and reach sexual maturity slowly, produce few, well-cared-for offspring, are typically larger-bodied and longer-lived, and typically exhibit a type I survivorship curve.
Organisms with an equilibrial life history
are born immigrate into an area, emigrate away, die
Population size fluctuates as new individuals
describes the expansion of a population in an ideal and unlimited environment
Exponential population growth
a few dozen rabbits can multiple into millions in certain circumstances following disasters, organisms that have opportunistic life history patterns can rapidly recolonize a habitat
Exponential growth explains how
are environmental factors that hold population growth in check restrict the number of individuals that can occupy a habitat
Limiting factors
the maximum population size that a particular environment can sustain
carrying capacity
occurs when the growth rate decreases as the population size approaches carrying capacity.
Logistic population growth
species resources available in the habitat.
The carrying capacity for a population varies, depending on the
environments where the population size is at or near carrying capacity
Organisms exhibiting equilibrial life history patterns occur in
competition between individuals of the same species for the same limited resources.
The logistic model is a description of infraspecific competition which is
is competition between individuals of the same species for the same limited resources.
Intraspecific competition
is a population-limiting factor whose effects intensify as the population increases in density.
density-dependent factor
accumulation of toxic wastes, limited food supply, limited territory.
Density-dependent factors may include
mortality was high, births and deaths were equal
From 2,000 to 500 years ago (in 1500),
Currently, In the most developed nations, the overall growth rates are near zero. In the developing world, death rates have dropped and high birth rates persist.
More recently, human population growth has been exponential