Unit 8: Ecology

N

population size

r max

maximum per capita growth rate of population

Adaptation

A trait that increases the survival and reproductive success of an organism.

Age Structure

The distribution of individuals of different ages within a population.

Biodiversity

The variety of life in an area, measured by species richness and evenness.

Biome

A large community of plants and animals that occupy a distinct region defined by climate and vegetation.

Biotic Factor

A living component of an ecosystem (e.g., plants, animals, bacteria).

Carbon Cycle

The movement of carbon through the biosphere, atmosphere, and geosphere.

Carrying Capacity

The maximum number of individuals an environment can support sustainably.

Climate Change

Long-term changes in temperature, precipitation, and other climate patterns.

Community

A group of interacting populations of different species in the same area.

Conservation

The protection and management of biodiversity and natural resources.

Decomposer

An organism that breaks down dead organic material, recycling nutrients back into the ecosystem.

Density-Dependent Factor

Factors that affect a population more strongly as its density increases, such as food availability and disease.

Food Chain

A linear sequence of organisms through which energy and nutrients flow.

Food Web

A complex network of interconnected food chains in an ecosystem.

Global Warming

The increase in Earth's average surface temperature due to human activities, primarily fossil fuel burning.

Greenhouse Effect

The trapping of heat in Earth's atmosphere by greenhouse gases, leading to global warming.

Gross Primary Productivity

The total amount of energy captured by primary producers (plants) in an ecosystem.

Habitat

The physical environment in which a species lives.

Hydrologic Cycle

The continuous movement of water on, above, and below Earth's surface.

Imprinting

A form of learning in which an animal forms an attachment to the first moving object it sees, often its parent.

Interspecific Competition

Competition between different species for the same resources.

Intraspecific Competition

Competition within the same species for resources.

K-Selection

A reproductive strategy characterized by fewer offspring with more parental care and longer life expectancy.

Keystone Species

A species that has a disproportionately large effect on its ecosystem relative to its abundance.

Nitrogen Cycle

The movement of nitrogen through the ecosystem, including fixation, assimilation, nitrification, and denitrification.

Parasite

An organism that lives in or on another organism (host) and benefits at the host's expense.

Photoautotroph

An organism that produces its own food using sunlight (e.g., plants, algae).

Population

A group of individuals of the same species living in the same area.

Population Growth

The change in the number of individuals in a population over time.

Pollution

The introduction of harmful substances into the environment.

Predator

An organism that hunts and kills another organism for food.

Primary Consumer

An herbivore that feeds on primary producers (plants).

Rate of Increase

The rate at which a population's size grows.

R-Selection

A reproductive strategy characterized by producing many offspring with little parental care.

Saprophyte

An organism that feeds on decaying organic matter, similar to a decomposer.

Detritivore

An organism that consumes dead organic material, like dead plants and animals.

Distribution

The geographic area where a species can be found.

Niche

The role and position of a species in its environment, including its habitat, interactions, and resources.

Primary Succession

Ecological succession that occurs in an area where no soil exists, such as after a volcanic eruption.

Secondary Succession

Ecological succession that occurs in an area where soil remains after a disturbance (e.g., fire).

Ecosystem

A community of organisms interacting with their physical environment.

Endangered Species

A species at risk of extinction due to a rapid decline in its population size.

Exponential Growth

A growth pattern in which the population size increases rapidly over time under ideal conditions.

• represented by a J-shaped curve

Limiting Factor

A factor that limits the growth, abundance, or distribution of a population.

Logistic Growth

A growth pattern where population growth slows as it approaches carrying capacity.

• starts slow, exponential growth, ends with stable maximum growth rate reached at carrying capacity

• S-shaped curve

Migration

The seasonal movement of organisms from one place to another.

Mutualism

A symbiotic relationship in which both species benefit.

Secondary Consumer

An organism that feeds on primary consumers (carnivores or omnivores).

Survivorship Curve

A graph that shows the number of individuals surviving at each age for a given species.

Symbiosis

A close relationship between two species, which can be mutualistic, commensal, or parasitic.

10% Rule

In an ecosystem, only about 10% of the energy from one trophic level is passed on to the next level.

Trophic Level

Each step in a food chain or food web, representing the flow of energy.

dN

change in population size

dt

change in time

B

birth rate

D

death rate

Factors that affect population growth are…

• age at reproductive maturity

• number of offspring produced

• frequency of reproduction

• survivorship of offspring to reproductive maturity

K

carrying capacity

Limiting factors impacting growth are…

• population density (how close individuals live near each other)

• abundance of foods leads to dense populations (high reprod rates, limited space)

• limited food leads to decrease in density of populations (lower reprod. rates, spread out individuals)

Density dependent factors

factors that impact population size as density changes

• competition

• territoriality

• disease

• predation

Density-independent factors

factors that impact population size regardless of the density of the population

• Natural disasters

• Pollution

Competitive exclusion principle

When two species have overlapping requirements in the same ecosystem, one species will outcompete the other for those overlapping resources.

“Bottom up”

Limitations in higher trophic levels as a result of energy availability in lower levels.

“Top down”

Controls on lower trophic levels from higher levels.