age structure
A population's age structure�the proportions of individuals at various ages�can have a strong effect on how rapidly it increases or decreases in size.
biotic potential
Species vary in their biotic potential or capacity for population growth under ideal conditions.
carrying capacity (K)
Together, biotic potential and environmental resistance determine the carrying capacity (K): the maximum population of a given species that a particular habitat can sustain indefinitely without being degraded.
coevolution
When populations of two different species interact in this way over a such long period of time, changes in the gene pool of one species can lead to changes in the gene pool of the other species. Such changes can help both sides to become more competitive
commensalism
is an interaction that benefits one species but has little, if any, effect on the other.
ecological succession
The gradual change in species composition in a given area is called ecological succession, during which, some species colonize an area and their populations become more numerous, while populations of other species decline and may even disappear.
environmental resistance
is the combination of all factors that act to limit the growth of a population.
inertia, or persistence
It is useful to distinguish among two aspects of stability in living systems. One is inertia, or persistence: the ability of a living system, such as a grassland or a forest, to survive moderate disturbances.
interspecific competition
occurs when members of two or more species interact to gain access to the same limited resources such as food, light, or space.
intrinsic rate of increase (r)
is the rate at which the population of a species would grow if it had unlimited resources.
K-selected species
At the other extreme are competitor or K-selected species. They tend to reproduce later in life and have a small number of offspring with fairly long life spans.
logistic growth
involves rapid exponential population growth followed by a steady decrease in population growth until the population size levels off.
mutualism
two species behave in ways that benefit both by providing each with food, shelter, or some other resource.
parasitism
occurs when one species (the parasite) feeds on the body of, or the energy used by, another organism (the host), usually by living on or in the host.
population density
is the number of individuals in a population found in a particular area or volume.
population dynamics
Populations differ in factors such as their distribution, numbers, age structure (proportions of individuals in different age groups), and density (number of individuals in a certain space). Population dynamics is a study of how these characteristics of p
predation
In predation, a member of one species (the predator) feeds directly on all or part of a living organism of another plant or animal species (the prey) as part of a food web.
predator
In predation, a member of one species (the predator) feeds directly on all or part of a living organism of another plant or animal species (the prey) as part of a food web.
predator-prey relationship
Together, the two different species, such as lions (the predator or hunter) and zebras (the prey or hunted), form a predator-prey relationship.
prey
In predation, a member of one species (the predator) feeds directly on all or part of a living organism of another plant or animal species (the prey) as part of a food web.
primary succession
involves the gradual establishment of biotic communities in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem.
r-selected species
Species have different reproductive patterns that can help enhance their survival. Species with a capacity for a high rate of population increase (r) are called r-selected species
resilience
A second factor is resilience: the ability of a living system to be restored through secondary succession after a moderate disturbance.
resource partitioning
It occurs when species competing for similar scarce resources evolve specialized traits that allow them to use shared resources at different times, in different ways, or in different places.
secondary succession
The other more common type of ecological succession is called secondary succession, in which a series of communities or ecosystems with different species develop in places containing soil or bottom sediment.
tipping point
there are limits to the stresses that ecosystems and global systems such as climate can take. As a result, such systems can reach a tipping point, where any additional stress can cause the system to change in an abrupt and usually irreversible way that of