Unit 8: Ecology (copy)

Endotherms

Animals that generate their own body heat through metabolism.

Ectotherms

Animals that lack an internal mechanism to control body temperature.

Instinct

An inborn, unlearned behavior.

Learning

A change in behavior brought about by experience.

Imprinting

A process where offspring accept the first moving object they see as their mother.

Habituation

A form of learning where an animal learns not to respond to a stimulus.

Circadian rhythms

Internal clocks or cycles that regulate behavioral patterns such as daily sleep-wake cycles.

Pheromones

Chemical signals between members of the same species that stimulate olfactory receptors and affect behavior.

Agonistic behavior

Aggressive behavior resulting from competition for food or other resources.

Dominance hierarchies

Established ranks among members of a group based on dominance.

Territoriality

A behavior displayed when food and nesting sites are scarce.

Altruistic behavior

Unselfish behavior that benefits another organism at the individual’s expense.

Mutualism

A symbiotic relationship in which both organisms benefit.

Commensalism

A symbiotic relationship in which one organism benefits and the other is not affected.

Parasitism

A symbiotic relationship in which one organism harms its host.

Photoperiodism

The response of plants to changes in the amount of daylight and darkness.

Tropism

A turning in response to a stimulus.

Phototropism

Plant response to sunlight by bending toward light.

Gravitropism

Plant response to gravity—stems grow upward, while roots grow downward.

Thigmotropism

Plant response to touch, such as ivy growing around a trellis.

Ecology

The study of interactions between living things and their environments.

Biosphere

The entire part of the Earth where living things exist.

Ecosystem

The interaction of living and nonliving things.

Community

A group of populations interacting in the same area.

Population

A group of individuals belonging to the same species that interbreed.

Producers

Organisms that make their own food.

Primary consumers

Herbivores that eat producers.

Secondary consumers

Carnivores and omnivores that eat producers and primary consumers.

Tertiary consumers

Organisms that eat both primary and secondary consumers.

Decomposers

Organisms that break down dead material.

Keystone species

A species that is particularly important to an ecosystem.

10% rule

In a food chain, only about 10 percent of energy is transferred from one level to the next.

Ecological pyramid

A representation of energy flow, biomass, and numbers of members within an ecosystem.

Toxins

Substances that can be concentrated in the ecosystem and become more dangerous for those higher up the food chain.

Simpson’s Diversity Index

A formula used to measure biodiversity in a community.

Population growth

The difference between births and deaths divided by the population size.

Carrying capacity

The maximum number of individuals of a species that a habitat can support.

Density-independent factors

Factors that affect population size regardless of the population's density.

Density-dependent factors

Factors that affect population size based on the population's density.

Exponential growth

Rapid population increase in an ideal environment resulting in a J-shaped curve.

Ecological succession

The predictable progression of plant communities over time.

Primary succession

The process of ecological succession occurring in an area with no previous organisms.

Pioneer organisms

First organisms to colonize previously uninhabited areas, like lichens.

Human impact on the environment

Issues caused by humans such as greenhouse effect, ozone depletion, and pollution.