APES Unit 3: Populations

Generalist Species

Organisms that live in a variety of environments, eat a variety of food, have a broad ecological tolerance for environmental changes, and have an advantage when the environment changes

Specialist Species

Organisms that require a specific habitat, have a limited diet, have a narrow ecological tolerance for environmental conditions, and have an advantage in habitats that stay constant

Biotic Potential

Under ideal conditions with unlimited resources available, every population has a maximum potential for growth

Niche

An organisms position and role within a habitat that leads to greater chances of survival

Habitat

The natural environment where a particular species or organism lives and obtains the resources it needs to survive.

Range of Tolerance (Ecological Tolerance)

The range of environmental conditions (abiotic) that an organism or population can endure before experiencing injury or death

Adaptation

A trait that improves an individual’s fitness

Resource Partitioning

When two species divide a resource based on differences in their behavior or morphology

K - Selected Species

A species with a low intrinsic growth rate that causes the population to increase slowly until it reaches the carrying capacity of the environment

r - Selected Species

A species that has a high intrinsic growth rate, and their population typically increases rapidly

Overshoot

When a population becomes larger than the environment’s carrying capacity

Dieback

A rapid decline in a population due to death. Also known as die-off

Reproductive Strategy

The various patterns and traits an organism has evolved to maximize its reproductive success

Carrying Capacity (K)

The limit to the number of individuals that can be supported by an existing habitat or ecosystem, and is denoted as K

Survivorship Curve

A graph that represents the distinct patterns of species survival as a function of age

Type I Survivorship Curve

K-selected species typically have high survivorship until old age followed by high mortality

Type II Survivorship Curve

Constant mortality rate throughout life

Type III Survivorship Curve

High mortality early in life

Longevity

The state of living for a particularly long time, often beyond the average life expectancy

Limiting Resource

A resource that a population cannot live without and that occurs in quantities lower than the population would require to increase in size

Environmental Resistance

In an ecosystem, a measure of how much a disruption can affect flows of energy and matter

Logistic Growth

A growth model that describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment

Population Growth Rate

The number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period - also known as intrinsic growth rate

Population Growth Model

Mathematical equations that can be used to predict population size at any moment in time

Density Dependent Factor

A factor that influences an individual’s probability of survival and reproduction in a manner that depends on the size of the population

Density Independent Factor

A factor that has the same effect on an individual’s probability of survival and the amount of reproduction at any population size

Exponential Growth Model

A growth model that estimates a population’s future size after a period of time based on the biotic potential and the number of reproducing individuals currently in the population

J - Shaped Curve

The curve of the exponential growth model when graphed

S - Shaped Curve

The shape of the logistic growth model when graphed

Age Structure Diagram

A visual representation of the number of individuals within specific age groups for a country, typically expressed for males and females

Population Pyramid

An age structure diagram that is widest at the bottom and smallest at the top, typical of developing countries

Environmental Justice

The study of the disproportionate exposure to environmental hazards experienced by people of color, recent immigrants and people of lower socio-economic backgrounds - and is both an academic field and a social movement

Population Momentum

Continued population growth after growth reduction measures have been implemented

Demography

The study of human populations and population trends

Family Planning

The regulation of the number or spacing of offspring through the use of birth control

Total Fertility Rate (TFR)

An estimate of the average number of children that each woman in a population will bear throughout her childbearing years

Crude Death Rate (CDR)

The number of deaths per 1,000 individuals per year

Crude Birth Rate (CBR)

The number of births per 1,000 individuals per year

Replacement - Level Fertility

The total fertility rate required to offset the average number of deaths in a population in order to maintain the current population size

Infant Mortality Rate

The number of deaths of children under 1 year of age per 1,000 live births

Child Mortality Rate

The number of deaths of children under age 5 per 1,000 live births

Net Migration Rate

The difference between immigration and emigration in a given year per 1,000 people in a country

Developed VS Developing Countries

Developed - Countries that have relatively high levels of industrialization and income

Developing - Countries that have relatively low levels of industrialization and income

Life Expectancy

The average number of years an individual is expected to live based on statistical averages derived from a population's mortality rates - provides insights into the overall health, quality of life, and longevity of a population, influencing social and economic policies

Doubling Time

The number of years it takes a population to double

Rule of 70

A method which dictates that by dividing the number 70 by the percentage population growth rate we can determine a population’s doubling time

Theory of Demographic Transition

A theory that states that a country moves from high to lower birth and death rates as development occurs and that country moves from a preindustrial to an industrialized economic system

IPAT Equation

A conceptual representation of the three major factors that influence environmental Impact: Population of humans, Affluence, Technology

Population Stability

Population stability refers to a state where the size and composition of a population remain relatively constant over time, with birth rates balancing out death rates