Chapter 11: Ecology

Endotherms

Animals that generate their own body heat through metabolism.

Ectotherms

Animals that lack an internal mechanism to control body temperature.

Instinct

Inborn, unlearned behavior.

Learning

A change in behavior brought about by an experience.

Imprinting

When offspring accept the first moving object they see as their mother in the absence of their actual mother.

Critical period

A window of time when the animal is sensitive to certain aspects of the environment during imprinting.

Habituation

When an animal learns not to respond to a stimulus.

Circadian rhythms

Internal clocks or cycles that occur in animals and plants.

Pheromones

Chemical signals between members of the same species that affect behavior.

Agonistic behavior

Aggressive behavior that occurs due to competition for resources.

Dominance hierarchies

A social structure in which members of a group establish the most dominant members.

Territoriality

A behavior that occurs when food and nesting sites are scarce.

Altruistic behavior

Unselfish behavior that benefits another organism in the group at the individual's expense.

Mutualism

A symbiotic relationship in which both organisms benefit.

Commensalism

A symbiotic relationship in which one organism benefits without harming the other.

Parasitism

A symbiotic relationship in which one organism harms the other.

Tropism

A turning in response to a stimulus

Phototropism

The way plants respond to sunlight

Gravitropism

The way plants respond to gravity

Thigmotropism

The way plants respond to touch

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 that belong to the same species and that are interbreeding.

Gross Productivity

The total amount of organic matter produced by photosynthesis in an ecosystem.

Net Productivity

The amount of organic matter produced by photosynthesis in an ecosystem, minus the amount used by the producers for their own cellular energy needs.

Keystone Species

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

10% Rule

Only about 10% of the energy available at one trophic level is transferred to the next level.

Biomass Pyramid

A diagram that shows the amount of living organic matter at each trophic level in an ecosystem.

Pyramid of Numbers

A diagram that shows the number of individual organisms at each trophic level in an ecosystem.

Pyramid of Energy

A diagram that shows the amount of energy available at each trophic level in an ecosystem.

Toxins

Harmful substances that can accumulate in the tissues of organisms.

Concentration

The process by which toxins become more concentrated in the tissues of organisms at higher trophic levels.

Danger

The increased risk of harm to animals at higher trophic levels due to the concentration of toxins in their tissues.

Ecological succession

The predictable procession of plant communities over a relatively short period of time (decades or centuries).