| Term | Definition |
|---|---|
| generalist species | Species that can survive and reproduce in a wide variety of environmental conditions and food sources, and tend to be advantaged in changing habitats. |
| specialist species | Species that are adapted to specific environmental conditions and have narrow habitat requirements. |
| Term | Definition |
|---|---|
| biotic potential | The maximum reproductive rate of a population under ideal environmental conditions with unlimited resources. |
| invasive species | Non-native organisms introduced to an ecosystem that outcompete native species for resources and can disrupt ecological balance. |
| K-selected species | Species that tend to be large, produce few offspring, invest significant energy in each offspring, mature slowly with extended parental care, have long lifespans, and reproduce multiple times in their lifetime, typically in stable environments with high resource competition. |
| r-selected species | Species that tend to be small, produce many offspring, invest minimal energy in each offspring, mature early, have short lifespans, and may reproduce only once in their lifetime, typically in environments with low resource competition. |
| reproductive strategies | The different approaches species use for reproduction, which may vary along the K-selected to r-selected spectrum or change based on environmental conditions. |
| Term | Definition |
|---|---|
| cohort | A group of individuals of the same age in a population. |
| K-selected species | Species that tend to be large, produce few offspring, invest significant energy in each offspring, mature slowly with extended parental care, have long lifespans, and reproduce multiple times in their lifetime, typically in stable environments with high resource competition. |
| r-selected species | Species that tend to be small, produce many offspring, invest minimal energy in each offspring, mature early, have short lifespans, and may reproduce only once in their lifetime, typically in environments with low resource competition. |
| survivorship curve | A line graph that displays the relative survival rates of a cohort from birth to the maximum age reached by any member of that cohort. |
| Type I curve | A survivorship curve showing high survival rates throughout most of an organism's lifespan, with most deaths occurring at old age; typical of K-selected species. |
| Type II curve | A survivorship curve showing a relatively constant death rate throughout an organism's lifespan; typical of some K-selected species. |
| Type III curve | A survivorship curve showing high mortality rates early in life, with few individuals surviving to old age; typical of r-selected species. |
| Term | Definition |
|---|---|
| carrying capacity | The maximum population size that an environment can sustain indefinitely given available resources and conditions. |
| dieback | A sudden and severe decline in population size, often resulting from resource scarcity or environmental stress. |
| disease | An illness or disorder that affects organisms, often spreading more rapidly in stressed or overcrowded populations. |
| famine | A widespread scarcity of food leading to malnutrition and starvation in a population. |
| population overshoot | A situation where a population exceeds the carrying capacity of its environment, leading to resource depletion and environmental degradation. |
| resource depletion | The reduction or exhaustion of natural resources due to overuse or extraction. |
| Term | Definition |
|---|---|
| carrying capacity | The maximum population size that an environment can sustain indefinitely given available resources and conditions. |
| environmental factors | Physical and biological conditions in an environment that limit or support population growth, including resource availability and space. |
| fecundity | The biological capacity of a population to reproduce, which decreases when resources become scarce. |
| mortality | The death rate in a population, which increases when resource availability declines and resources are unequally distributed. |
| population growth | The increase in the number of individuals in a population over time, which is limited by environmental factors and available resources. |
| resource availability | The presence and accessibility of resources needed by a population, such as food, water, and space, which directly influences the rate and sustainability of population growth. |
| resource base | The total amount of resources available to support a population, which is finite and limited over all time scales. |
| Term | Definition |
|---|---|
| age structure diagrams | Visual representations of the distribution of a population by age groups, typically displayed as horizontal bar charts that show the proportion of males and females at each age level. |
| declining population | A population with a lower proportion of younger individuals compared to older individuals, indicating a decrease in population size over time. |
| population growth rate | The rate at which a population increases or decreases over time, which can be determined by analyzing the shape and proportions shown in age structure diagrams. |
| rapidly growing population | A population characterized by a high proportion of younger individuals relative to older individuals, typically indicated by a wide base in an age structure diagram. |
| stable population | A population with relatively equal proportions across age groups, indicating little change in population size over time. |
| Term | Definition |
|---|---|
| age at first child | The age at which a female has her first child; a factor that affects total fertility rate and population growth patterns. |
| educational opportunities for females | Access to schooling and learning for women and girls; increased education is associated with lower fertility rates. |
| family planning | Access to contraception, reproductive health services, and information that allows individuals to control the timing and number of children they have. |
| government acts and policies | Laws and government programs that influence population growth, such as incentives or restrictions on family size. |
| infant mortality rate | The number of deaths of infants under one year of age per 1,000 live births in a given population. |
| maternal healthcare | Medical services and support provided to mothers during pregnancy, childbirth, and postpartum; affects infant survival rates. |
| nutrition | Adequate food and nutrients necessary for health; maternal and infant nutrition affects infant mortality rates. |
| replacement level | The fertility rate at which a population replaces itself from one generation to the next, typically around 2.1 children per female in developed countries. |
| total fertility rate (TFR) | The average number of children a female is expected to have in her lifetime; a key measure of population growth and demographic change. |
| Term | Definition |
|---|---|
| birth rate | The number of live births per unit of population (typically per 1,000 people) in a given time period. |
| carrying capacity | The maximum population size that an environment can sustain indefinitely given available resources and conditions. |
| death rate | The number of deaths per unit of population (typically per 1,000 people) in a given time period. |
| density-dependent factors | Environmental factors that limit population growth and become more severe as population density increases, such as disease and competition for resources. |
| density-independent factors | Environmental factors that limit population growth regardless of population density, such as natural disasters or extreme weather events. |
| family planning | Access to contraception, reproductive health services, and information that allows individuals to control the timing and number of children they have. |
| infant mortality rate | The number of deaths of infants under one year of age per 1,000 live births in a given population. |
| Malthusian theory | The theory that human population grows exponentially while food supply grows linearly, leading to resource scarcity and population limitations. |
| population doubling time | The number of years required for a population to double in size at a given growth rate. |
| rule of 70 | A mathematical principle stating that dividing 70 by the percentage population growth rate approximates how many years it takes for a population to double in size. |
| Term | Definition |
|---|---|
| birth rate | The number of live births per unit of population (typically per 1,000 people) in a given time period. |
| death rate | The number of deaths per unit of population (typically per 1,000 people) in a given time period. |
| demographic transition | The transition from high to lower birth and death rates in a country or region as development occurs and the country moves from a preindustrial to an industrialized economic system. |
| demographic transition model (DTM) | A four-stage model that demonstrates the transition from high to lower birth and death rates as a country develops from preindustrial to industrialized. |
| developed country | Countries with higher levels of economic development, typically characterized by lower infant mortality rates and less reliance on child labor. |
| developing country | Countries with lower levels of economic development, typically characterized by higher infant mortality rates and greater reliance on child labor. |
| industrialized economic system | An economic system characterized by the development of large-scale manufacturing, mechanization, and factory-based production. |
| infant mortality rate | The number of deaths of infants under one year of age per 1,000 live births in a given population. |
| preindustrial | A stage of economic development before industrialization, characterized by economies based primarily on agriculture and manual labor. |