age structure
The proportions of individuals at various ages.A population's age structure can have a strong effect on how rapidly it increases or decreases in size.
biotic potential
Capacity for population growth under ideal conditions.Species vary in this.Generally, populations of species with large individuals, such as elephants and blue whales, have a low biotic potential while those of small individuals, such as bacteria and insects, have a high biotic potential.
carrying capacity (K)
The maximum population of a given species that a particular habitat can sustain indefinitely without being degraded.The biotic potential and environmental resistance determine this when put together.
coevolution
Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo adaptations.Ex: The relationship between bats and moths: bats hunt at night and emit sounds when capturing moths to eat, so overtime, certain moth species have evolved ears that are sensitive to these sound frequencies that bats use to find them. Bats have also responded back by evolving ways to change the frequency of their sound pulses.
commensalism
An interaction that benefits one species but has little, if any, effect on the other.Ex: flatworms attach themselves to crabs and eat their food, but the crabs are not harmed
ecological succession
Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities.Ex: forests undergo changes in their species composition over long periods of time
environmental resistance
The combination of all factors that act to limit the growth of a population.
exponential growth
Growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time.
inertia (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.Ex: leopards and lions feed on the same prey
K-selected species
Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age.Ex: most large mammals (such as elephants, whales, and humans), birds of prey, and large and long-lived plants (such as saguaro cactus, and most tropical rain forest trees)
intrinsic rate of increase (r)
The rate at which the population of a species would grow if it had unlimited resources.
logistic growth
Involves rapid exponential population growth followed by a steady decrease in population growth until the population size levels off.
mutualism
An interaction that benefits both species by providing each with food, shelter, or some other resource.Ex: the oxpecker bird and a rhinoceros or zebra
parasitism
Occurs when one organism (the parasite) feeds on the body of, or the energy used by, another organism (the host), usually by living on or in the host.Ex: tapeworms attach themselves to the inside intestines of cows, pigs, and humans
population density
Number of individuals in a population found in a particular area or volume.
population crash
The sudden decline in the numbers of individual members in a population, species or group of organisms.*This usually occurs when individuals don't have enough resources to survive.
population dynamics
Major abiotic and biotic factors that tend to increase or decrease the population size and effect the age and sex composition of a species.*The study of how characteristics of populations change in response to changes in environmental conditions.
predation
Occurs when a member of one species (the predator) feeds directly on all or part of a member of another species (the prey).Ex: bears feed on fish
predator
Organism that captures and feeds on parts or all of an organism of another species (the prey).Ex: lions, zebras, bears (eat fish)
predator-prey relationship
Relationship that has evolved between two organisms, in which one organism has become the prey for the other, the latter called the predator.
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.
resilience
The ability of a living system to be restored through secondary succession after a moderate disturbance.
prey
Organism that is captured and serves as a source of food for an organism of another species (the predator).Ex: fish (eaten by bears), rabbit (eaten by fox)
r-selected species
Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period.Species with a capacity for high rate of population increase (r).Ex: algae, bacteria, rodents, frogs, turtles, annual plants (such as dandelions), and most insects
secondary succession
Where a series of communities or ecosystems with different species develop in places containing soil or bottom sediment.
resource partinioning
Process of dividing up resources in an ecosystem so that species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places.
S curve
The shape of a population curve after a population size has stabilized.
founder effect
When few individuals in a population colonize a new habitat.
chemical warfare
A method in which a prey could discourage a predator through the use of chemicals.
demographic bottleneck
This occurs when only a few individuals of a population survive a catastrophe.
succession
The gradual change in species composition in a given area over time.
deceptive looks
Looking like a larger animal is an example of this type of prey survival method.
density
Number of individuals found in a particular area/volume.
inertia
The ability of a living system to survive moderate disturbances.
deceptive behavior
Actions taken by prey to scare off a predator.
intrinsic rate of increase
The rate at which a population could grow given unlimited resources.
genetic drift
A change in gene frequency that could hinder the survivability of a population.
warning coloration
Message to predators that "I taste bad/am poisonous/etc.
K selected species
Species with slow rate of population increase; a few individuals, but big and strong.
camouflage
A disguise used by prey to "hide in plain sight.
dieback
The crash that can happen from exceeding the carrying capacity of an environment.
R selected
Populations with a high rate of population increase.
coevolution
A process by which changes in one species' gene pool can lead to changes in another species' gene pool.
overshot
To temporarily exceed the carrying capacity of an environment.
environmental resistence
The combination of all factors that act to limit the growth of a population.
inbreeding
If a population is small and lacks possible mates, this tends to happen.
resource partitioning
What occurs when species competing for the same scarce resource evolve to "share" the resource in different ways/times.
mimicry
Looking like something undesirable by a predator in order to protect yourself.
tipping point
The point at which any additional stress can cause a system to change in a (usually) uninterruptible way.
carrying capacity
The maximum population of a species population that can be supported without degrading the environment.
J curve
The beginning shape of a growth curve of a population growing exponentially.