CHAPTER 34: The Biosphere: An Introduction to Earth’s Diverse Environments & CHAPTER 36: Population Ecology

Ecology

The scientific study of the interactions of organisms with their environment.

Biotic factors

Living components of the environment, including organisms.

Abiotic factors

Nonliving components of the environment, such as physical features, chemical factors, temperature, forms of energy, water, and nutrients.

Habitat

The specific environment an organism lives in, including both abiotic and biotic factors.

Organism level

How one kind of organism meets the challenges and opportunities of its environment through physiology or behavior.

Population

A group of individuals of the same species living in a particular geographic area.

Community

The assemblage of all the populations of organisms living close enough for potential interaction.

Ecosystem

The biotic and abiotic components of the environment.

Biosphere

An area extending from the atmosphere several kilometers above Earth to the depths of the ocean; all of Earth that is inhabited by life.

Silent Spring

A book by Rachel Carson that highlighted the environmental issues caused by the pesticide DDT.

Energy source

All organisms require a source of energy to live, such as sunlight for photosynthetic organisms.

Temperature

An important abiotic factor affecting metabolism; extremes can hinder biological functions.

Water

Essential for all life.

Population ecology

The branch of ecology that studies changes in population size and the factors that regulate populations over time.

Population density

The number of individuals of a species per unit area or volume.

Dispersion Pattern

The way individuals are spaced within their area.

Clumped Dispersion Pattern

Individuals are grouped in patches; results from unequal distribution of resources.

Uniform Dispersion Pattern

Results from interactions between the individuals of a population, such as territorial behavior.

Random Dispersion Pattern

Individuals in a population are spaced in an unpredictable way.

Life tables

Tools that track survivorship and the chances of individuals surviving to various ages.

Survivorship curves

Graphs that plot survivorship as the proportion of individuals from an initial population that are alive at each age.

Type I Survivorship

Most individuals survive to older age intervals, with dramatic declines in older age.

Type II Survivorship

Individuals have a constant rate of mortality regardless of age.

Type III Survivorship

Low survivorship for the very young, but high for those that survive to a certain age.

Population size

Fluctuates as new individuals are born or immigrate, and others die or emigrate.

Exponential growth

The rate of population increase under ideal conditions.

Carrying Capacity

The maximum population size that a particular environment can sustain.

Logistic Growth Model

Describes population growth slowed by limiting factors as population size increases.

Density-dependent factors

Limiting factors whose intensity is related to population density.

Intraspecific Competition

Competition among individuals of the same species for limited resources.

Density-independent factors

Population-limiting factors unrelated to population density; examples include climate changes.

Boom-and-bust cycle

Dramatic fluctuations in population density, characterized by rapid growth followed by sharp declines.

Life history

Traits affecting an organism’s reproductive schedule and longevity.

r-selection

Reproductive strategy in environments with abundant resources allowing for exponential growth.

K-selection

Reproductive strategy where species produce fewer offspring but invest more care in each.

Sustainable Resource Management

Harvesting crops without destroying the resource.

Demographic Transition

A shift from high birth and death rates to lower rates.

Age Structure

The number of individuals in different age groups within a population.

Fertility Rate

The average number of children produced by a woman over her lifetime.

Population Momentum

The increased proportion of women of childbearing age in a population.

Ecological footprint

An estimate of land and water area required to provide the resources consumed by individuals or nations.