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  1. AP Environmental Science
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Glossary

B

Biotic potential

Criticality: 2

The maximum reproductive capacity of a population under ideal environmental conditions, representing the highest possible growth rate.

Example:

A single bacterium, under perfect conditions, has an immense biotic potential, capable of producing millions of descendants in just a few hours.

C

Carrying capacity

Criticality: 3

The maximum population size of a biological species that can be sustained indefinitely by a given environment, considering the available resources.

Example:

The deer population in a national park will eventually stabilize around its carrying capacity as food and habitat become limiting factors.

E

Ecological Succession

Criticality: 3

The gradual process of change in the species structure of an ecological community over time, often following a disturbance or in newly formed habitats.

Example:

After a forest fire, the regrowth of vegetation from grasses to shrubs and eventually trees is an example of ecological succession.

Exponential growth

Criticality: 2

Population growth that occurs when a population's per capita growth rate remains constant, resulting in a rapid, accelerating increase in population size over time, often seen in r-selected species.

Example:

In a lab setting with unlimited nutrients, a bacterial colony can exhibit exponential growth, doubling its numbers at a fixed rate.

I

Invasive species

Criticality: 3

A non-native species whose introduction to an ecosystem causes or is likely to cause environmental or economic harm, often characterized by r-selected traits.

Example:

The zebra mussel is an invasive species in North American waterways, outcompeting native mussels and clogging pipes.

K

K-selected species

Criticality: 3

Species characterized by a low reproductive rate, few large offspring, extensive parental care, and long lifespans, typically found in stable, competitive environments near their carrying capacity.

Example:

The long gestation period and intensive maternal care of a grizzly bear exemplify a K-selected species focused on the survival of a few high-quality offspring.

L

Late-successional species

Criticality: 2

Species that dominate the later stages of ecological succession, typically K-selected, characterized by slower growth, longer lifespans, and strong competitive abilities.

Example:

Large, shade-tolerant redwood trees are late-successional species that thrive in mature, stable forest ecosystems.

P

Pioneer species

Criticality: 2

The first species to colonize newly disturbed or barren environments, often r-selected due to their rapid reproduction and dispersal abilities.

Example:

Lichens are classic pioneer species that can grow on bare rock, slowly breaking it down to create soil for other plants.

R

Reproductive Strategies

Criticality: 3

Different approaches species adopt to maximize their survival and the passing on of their genes, typically categorized along a spectrum from r-selected to K-selected.

Example:

An organism's reproductive strategy determines whether it produces many offspring with little care or few offspring with extensive parental investment.

S

Survivorship Curve

Criticality: 3

A graph that illustrates the number or proportion of individuals surviving at each age for a given species or group, revealing patterns of mortality over a lifespan.

Example:

By analyzing a population's survivorship curve, ecologists can understand if most individuals die young, live to old age, or have a constant mortality risk.

T

Type I Survivorship Curve

Criticality: 2

A survivorship curve characterized by high survival rates throughout most of the lifespan, with mortality increasing sharply in old age, typical of K-selected species.

Example:

Modern human populations often display a Type I Survivorship Curve, where most individuals survive well into adulthood due to healthcare and stable conditions.

Type II Survivorship Curve

Criticality: 2

A survivorship curve characterized by a relatively constant mortality rate throughout the lifespan, meaning individuals are equally likely to die at any age.

Example:

Many bird species exhibit a Type II Survivorship Curve, facing a consistent risk of predation or disease regardless of their age.

Type III Survivorship Curve

Criticality: 3

A survivorship curve characterized by very high mortality rates early in life, with much lower mortality for those few individuals who survive to adulthood, typical of r-selected species.

Example:

A sea turtle laying hundreds of eggs, most of which will not survive to maturity, demonstrates a classic Type III Survivorship Curve.

r

r-selected species

Criticality: 3

Species characterized by a high reproductive rate, many small offspring, little to no parental care, and short lifespans, often thriving in unstable or newly disturbed environments.

Example:

A sudden outbreak of mosquitoes after heavy rainfall is typical of an r-selected species, rapidly exploiting temporary abundant resources.