Global Demographics, Population Dynamics, and Ecological Systems

Vocabulary practice flashcards covering Human Geography, Demographic Transition, Migration Models, Ecology, Genetics, and Evolutionary Biology.

Rate of Natural Change

The birth rate minus the death rate of a population, expressed as a percentage.

Fertility Rate

The average number of children born per woman of childbearing age (usually ages 15 to 49) during her lifetime.

Replacement Rate

The fertility rate required for population replacement, currently considered around $2.1$ babies per woman to replace herself and her partner.

Infant Mortality Rate (IMR)

The number of deaths of infants before their first birthday per 1,000 live births.

Life Expectancy

An estimate of the average age that members of a particular population group will be when they die.

Population Momentum

The phenomenon where a population continues to grow even after fertility rates decline, due to a large existing female population in childbearing years (15-45).

Negative Population Momentum

A condition in lowest-low fertility countries where population decline occurs even if fertility rates rise back toward the replacement level of $2.1$.

Human Development Index (HDI)

A composite statistic combining life expectancy, education, and income indices to rank countries into four tiers of human development.

Refugee

A person who has fled their own country due to a well-founded fear of persecution based on race, religion, nationality, social group, or political opinion.

Asylum Seeker

A person who has fled their country seeking protection because their life is at risk, but whose claim for refugee status has not yet been formally assessed.

Forced Migration

The movement of people away from their home area against their will or as a result of life-threatening circumstances such as natural hazards, war, or persecution.

Voluntary Migration

Relocation that occurs when a migrant chooses to move to a new location based on pull factors like better employment, higher wages, or lifestyle opportunities.

Demographic Transition Model (DTM)

A system theory model tracking changes in birth rates, death rates, and natural increase to describe population features as a nation undergoes economic development across five stages.

Rostow's Five Stages of Economic Growth

A modernization theory model outlining economic and demographic evolution through Traditional Society, Preconditions for Take-off, Take-off, Drive to Maturity, and Age of High Mass Consumption.

Wallerstein's Modern World System

A framework explaining global economic disparity by categorizing regions into Core, Semi-peripheral, and Peripheral tiers based on economic structure and trade dynamics.

Murdie's Model of Residential Structure

An urban structure model depicting physical space layered with economic status, family status, and ethnic status within a city.

Biodiversity

The variability among living organisms from all sources (terrestrial, marine, and aquatic) and the ecological complexes of which they are a part, including diversity within species, between species, and of ecosystems.

Species Richness

The total number of different species present within a given sample or defined ecological area.

Relative Species Abundance

The percentage composition of an organism of a particular kind relative to the total number of organisms in an area, representing species evenness.

Simpson's Diversity Index

A calculated measure of species diversity taking into account both species richness and relative abundance, producing a value between $0$ and $1$.

Binomial Nomenclature

A two-part scientific naming system for organisms consisting of a capitalized genus name and a lowercase species name, formatted in italics.

r/K Selection

A classification system based on reproductive strategies, distinguishing between species producing massive offspring with no parental care ($r$-selection) versus few offspring with extended parental investment ($K$-selection).

Clade

A group of organisms consisting of a common ancestor and all of its evolutionary descendants, including both living and extinct species.

Biological Species Concept

The definition of a species as groups of interbreeding natural populations that are reproductively isolated from other such groups.

Stratified Sampling

A sampling technique in which an area is divided into distinct, non-overlapping homogeneous sub-sections (strata) before sampling to obtain proportionate data.

Gross Primary Production (GPP)

The total amount of organic matter produced in an ecosystem as a result of photosynthesis or chemosynthesis.

Net Primary Productivity (NPP)

Gross primary production minus the rate of energy loss to metabolism and maintenance in autotrophic producers.

Ecological Niche

The functional role and position a species occupies within its environment, encompassing how it uses resources and interacts with its community.

Competitive Exclusion Principle

The ecological rule stating that if two species rely on the exact same limiting resource in an environment, one will out-compete the other, forcing it into extinction or niche shift.

Keystone Species

An organism that plays a critical role in defining and maintaining the structure, balance, and biodiversity of an entire ecosystem.

Carrying Capacity

The maximum population size of a species that can be sustainably supported in a given environment by its available resources.

Lincoln Index

A capture-mark-recapture sampling formula used to estimate total population size $N$ given by $N = \frac{M \times n}{m}$.

Ecological Succession

The progressive process where community composition changes over time as one plant/animal community is gradually replaced by another.

Pioneer Species

Hardy, fast-growing, usually autotrophic organisms that are the first to colonize bare or disrupted environments.

Climax Community

The final, stable stage of ecological succession where plant and animal populations remain in equilibrium with each other and their environment.

Nucleosome

A structural unit of eukaryotic chromatin composed of about 200 base pairs of DNA wrapped around an octamer of 8 histone proteins.

Polymerase Chain Reaction (PCR)

A molecular biology technique used to rapidly make millions of copies of a specific DNA sequence through automated thermal cycling.

Aneuploidy

A condition in which a cell or organism has an abnormal chromosome number due to the loss or gain of individual chromosomes.

Non-disjunction

The failure of homologous chromosomes or sister chromatids to separate normally during cell division, leading to aneuploid daughter cells.

Homeotic Genes (Hox Genes)

A group of developmental genes containing a 180-nucleotide homeobox sequence that regulates embryonic body plan organization and anatomical structures.

Adaptive Radiation

The rapid evolutionary diversification of a single ancestral lineage into multiple new species occupying different ecological niches.

Stabilising Selection

A type of natural selection that favours intermediate phenotypic traits and removes extreme variations in stable environmental conditions.

Directional Selection

A form of natural selection that favours individuals displaying one extreme phenotypic trait, shifting allele frequencies in response to environmental change.

Disruptive Selection

Natural selection that simultaneously favours individuals at both phenotypic extremes while selecting against average intermediate phenotypes.

Genetic Drift

Random changes in allele frequencies within a gene pool over generations, which can cause loss of genetic variation, especially in small populations.

Allopatric Speciation

Speciation triggered by geographic separation that physically isolates populations and prevents gene flow between them.

Sympatric Speciation

The emergence of a new species from a single ancestral species while both inhabit the exact same geographic region.