APES Unit 2 Chapter 7 of the Exploring Environmental Science for AP, 1st Edition

Survivorship curve

Graph showing the number of survivors in different age groups for a particular species.

Secondary ecological succession

ecological succession in an area in which natural vegetation has been removed or destroyed but the soil or bottom sediment has not been destroyed.

r-selected species

organisms that have short lifespans, produce many, usually small offspring to which they give little or no parental care.

Resource partitioning

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.

Resilience

ability of a living system such as a forest or pond to be restored through secondary ecological succession after a severe disturbance.

Range of tolerance

range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally.

Primary ecological succession

ecological succession in an area without soil or bottom sediments.

Prey

organism that is killed by an organism of another species (the predator) and serves as its source of food.

Predator–prey relationship

Relationship that has evolved between two organisms, in which one organism has becomes the prey for the other, the latter called the predator.

Predator

Organism that captures and feeds on some or all parts of an organism of another species (the prey).

Population Size  

Number of individuals making up a population(s) gene pool.

Population Density

number of organisms in a particular population found in a specified area or volume.

Population

group of individual organisms of the same species living in a particular area.

Pioneer Species 

The first hardy species often microbes, mosses, and lichens that begin colonizing a site as the first stage of ecological succession.

Persistence

ability of a living system such as a grassland or forest to survive moderate disturbances.

Parasitism

interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host.

Mutualism

type of species interaction in which both participating species generally benefit.

Limiting Factor

single factor that limits the growth, abundance, or distribution of a population of a species in an ecosystem.

K-selected Species

organisms that reproduce later in life, have few offspring and invest energy in raising and nurturing those offspring, and have long lifespans.

Interspecific Competition 

Attempts by members of two or more species to use the same limited resources in an ecosystem.

Environmental Resistance

all of the limiting factors that act together to limit the growth of a population.

Ecological succession

Process in which communities of plant and animal species in a particular area are replaced over time by a series of different often more complex communities.

Commensalism

an interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree.

Coevolution

Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo adaptations.

Carrying Capacity

Maximum population of a particular species that a given habitat can support over a given period.

Age Structure 

Distribution of individuals in a population among various age groups.