Unit 5 Exam - Populations

Population

Individuals of the same species living in the same area at a particular time

Size, density, distribution, ratio, age structure

Distinctive population characteristics

Population Size

The number of organisms in an area at a given time

Population growth

Population dynamic with abundant resources

Population decrease

Population dynamic with scarce resources, increased mortality and decreased fecundity

Fecundity

The ability to reproduce

Population density

The number of individuals per unit area

Population Distrubution

Spatial arrangement of organisms within an area

Random

Population distribution with no particular pattern

Uniform

Population distribution where individuals are spread evenly

Clumped

Population distribution where individuals are concentrated in certain areas

Sex Ratio

Proportion of males to females, usually 1:1 in monogamous species, varies in others

Age Structure

Number of individuals of different ages within a population, predicts population growth of shrinkage

Survivorship Curve (Life History Strategies)

Chart that represents how natural selection influences reproduction, survival, and lifespan. Age vs number of survivors

Type III

Survivorship curve representing many offspring →less/no care, survival rate due to changes, r-selected, unstable environments. Mortality rates high early in life

Type II

Survivorship curve representing the middle of the spectrum, relatively constant mortality rate at all ages

Type I

Survivorship curve with few offspring, invest heavily in their survival, K-selected, stable environments. Mortality rates high late in life

K-Selected species

Quality, long life span, long time to reproductive maturity, few reproductive events, few and large offspring, parental care, slow growth rate, density dependent, stable - near carrying capacity. Low biotic potential, less likely to adapt, bottleneck

r-selected

Quantity, short life span, young reproductive maturity, many events, small and many offspring, no parental care, fast growth rate, density independent, highly variable population. High biotic potential, often invasive

Natality, Mortality, Immigration, Emmigration

Four key factors of population dynamics

Natality

Births within a population

Morality

Deaths within a population

Immigration

Arrival of individuals from outside a population

Emmigration

Departure of individuals from a population

Exponential Growth

Growth of a population where it increases by a fixed percentage each year

Biotic Potential

Max rate of increase in a population under ideal conditions →Low population, low competition, good conditions

Logistic Growth

Growth of a population that accounts for limiting factors and constraints on population growth. S-shaped curve

Carrying Capacity

The max number of individuals an environment can sustain, population growth slows as it approaches the max

IPAT

Formula that represents the human impact on the environment. Multiplies population by affluence by technology

Population

Factor of environmental impact that revolves around humans taking up more space and resources while generating more waste

Affluence

Factor of environmental impact that involves greater per capita resource consumption

Technology

Factor of environmental impact that revolves around humans enhancing our ability to exploit resources or decrease impact by improving efficiency

Sensitivity Factor (S)

Factor that may be added to IPAT to show the vulnerability of a given environment

Global Distribution

The overall spread of humans, often clumped, densest in temperate, subtropical, and tropical climates

Increasing

Type of age structure diagram with a large percent of the population in pre-reproductive ages, small percent in post-reproductive age

Stable

Type of age structure diagram with a similar percent of ages in all stages of life

Decreasing

Type of age structure diagram with a small percent of the population in pre-reproductive age, with a larger post-reproductive percent

Age Structure Diagram

AKA population pyramid, describe the relative numbers of individuals at each age class in a population. Used to predict future growth of populations

Total Fertility Rate (TFR)

A statistic relating to the average number of children born per woman during her lifetime

Causes of high TFR

Demographic fatigue, no money to help with poverty, education, food, jobs, or to treat disease

Replacement Fertility

The TFR that keeps the size of the population stable, 2.1 for humans (higher than 2 to account for infant mortality)

Preindustrial

Stage of transition with high death rate (disease, poor healthcare, unreliable food supplies), high infant mortality (compensated for with many children), no birth control, stable population growth

Transitional

Stage of transition with a decline in death rates (better food production and healthcare), birth rates still high (society has not adjusted yet), very high population growth rate

Industrial

Stage of transition where birth rates decrease (Women employed, birth control available & acceptable), population growth slows and begins to stabilize

Post-Industrial

Stage of transition where population growth stabilizes or begins to shrink, US in this stage (even with higher growth rates due to an increased immigration rate)

Demographic Fatigue

The inability of a country to transition from one stage to another due to overpopulation and often prevalence of HIV/AIDS

Family Planning Programs

Programs in countries designed to decrease the population size and TFR, methods to slow growth are diverse, flexible, and culturally specific

Top Down

Type of policy that involves government regulation and broad goals from authorities and pushes them down to influence the amount of kids couples can have

Bottom Up

A type of family planning that emphasizes addressing poverty and social needs first without widespread regulation