ecology quiz

Population

A group of individuals of the same species living at the same place at the same time.

Community

A group of populations living at the same place at the same time.

Ecosystem

All of the living and nonliving factors that affect an organism in a specific area.

Biosphere

All of the portions of Earth that support life.

Habitat

The area where an organism lives out its life.

Niche

The role or position of a species in an ecosystem.

Population ecology

The study of growth, abundance, and distribution of populations.

Size (represented by N)

The total number of individuals.

Population density

The number of individuals from a population per area or volume.

Dispersion

How a population is distributed throughout an ecosystem.

Clumped dispersion

Organisms are huddled together and tightly packed.

• Example: Ants

Uniform dispersion

Organisms are evenly dispersed.

• Example: Penguins, orchard farms

Random dispersion

There's no detectable pattern in how the population is dispersed.

• Example: Dandelions

Age structure

A diagram that shows how the individuals in a population are distributed by gender and age.

Pyramid

Indicates rapid population growth.

Tiered

Indicates slow population growth.

Rectangular or urn-shaped

Indicates zero/decreasing population growth.

Type I survivorship curve

Individuals are more likely to die when old.

• Example: Humans, gorillas

Type II survivorship curve

Individuals have an equal chance of dying at any age.

• Example: Rats, squirrels

Type III survivorship curve

Most individuals die young.

• Example: Fish, oysters

Biotic Potential

The maximum growth rate of a population under ideal conditions.

Carrying capacity

The maximum number of individuals of a population that can be sustained by a particular habitat.

Density-dependent factors

Factors that intensify as the population gets bigger.

• Example: Disease, competition for food.

Density-independent factors

Factors that affect populations regardless of size.

• Example: Fires, volcanic eruptions, hurricanes.

r = (births - deaths)/N

A formula used for calculating the population growth rate.

Intrinsic rate

The maximum reproductive rate of an individual; occurs when r is at its maximum (biotic potential).

Zero population growth

Occurs when births = deaths ; the birth rate is equal to the death rate.

Exponential growth

As the population increases, it grows faster; represented by a J-shaped curve.

Logistic growth

As the population increases, it grows slower; starts off exponentially but then slows down and stops due to density-dependent factors; represented by an S-shaped curve.

Short lifespan, many offspring, little parental care.

Characteristics of r-selected species.

Long lifespan, few offspring, and lots of parental care.

Characteristics of K-selected species.

Mosquitoes, mice, dandelions.

Examples of r-selected species.

Humans, elephants

Examples of K-selected species.

Competitive exclusion principle

States that no two species can coexist if they occupy the same niche.

Resource partitioning

A process that avoid competition by taking a large niche and splitting it into smaller niches.

Fundamental niche

The niche that an organism occupies in the absence of competing species.

Realized niche

The niche competition organisms occupy and prevent competition, resulting in no niche overlap; a direct result of resource partitioning.

Local extinction

The termination of a species within a specific geographic area, although the species still exists elsewhere in the world.

Symbiosis

An interaction of two or more individuals of different species.

Mutualism

A type of symbiosis where all of the species benefit.

Commensalism

A type of symbiosis where one species benefits and the other species doesn't benefit but is unharmed.

Parasitism

A type of symbiosis where one species benefits and the other species is harmed.

True predator

A predator that kills and eats animals.

Parasite

An organism that lives on another organism and feeds on its tissues; benefits in parasitism.

Parasitoid

An insect that lays eggs inside a host; the larva devours the host until they are fully developed.

Herbivore

A predator that feeds on plant matter.

Grainivores

Herbivores that eat grains.

Frugivores

Herbivores that eat fruits.

Grazers

Herbivores that eat grass.

Browsers

Herbivores that eat leaves.

Primary succession

Life that colonizes on an area that was previously uninhabited.

Pioneer species

The first species to populate an area during primary succession; not good at competition.

Secondary succession

The natural process by which ecosystems recover and regrow after a disturbance that doesn't destroy the soil; occurs when an existing community is disrupted (example: fires, hurricanes)

Climax community

The final stage of ecological succession; forms a stable and long-lasting community of plants, animals, and other organisms; stays relatively stable over time.

Marginal habitats

Environments where conditions aren't ideal for most species to live and thrive in; contains low or unpredictable resources, extreme conditions, and high competition or disturbances.