| A | B |
|---|
| age structure | Percentage of the population (or number of people of each sex) at each age level in a population. |
| annual | Plant that grows, sets seed, and dies in one growing season. |
| asexual reproduction | Reproduction in which a mother cell divides to produce two identical daughter cells that are clones of the mother cell. This type of reproduction is common in single–celled organisms. |
| biotic potential | Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth. |
| carrying capacity (k) | Maximum population of a particular species that a given habitat can support over a given period. |
| climax community | Also called a mature community. |
| coevoloution | Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo adaptations. |
| commensalism | An interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree. |
| competition | Two or more individual organisms of a single species or two or more individuals of different species attempting to use the same scarce resources in the same ecosystem. |
| dieback | Sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat. |
| dissolved oxygen (DO) content | Amount of oxygen gas (O2) dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water. |
| ecological succession | Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities. |
| environmental resistance | All of the limiting factors that act together to limit the growth of a population. |
| epiphyte | Plant that uses its roots to attach itself to branches high in trees, especially in tropical forests. |
| host | Plant or animal on which a parasite feeds. |
| immature community | Community at an early stage of ecological succession. It usually has a low number of species and ecological niches and cannot capture and use energy and cycle critical nutrients as efficiently as more complex, mature communities. |
| interspecific competition | Attempts by members of two or more species to use the same limited resources in an ecosystem. |
| intraspecific competition | Attempts by two or more organisms of a single species to use the same limited resources in an ecosystem. |
| intrinsic rate of increase (r) | Rate at which a population could grow if it had unlimited resources |
| limiting factor | Single factor that limits the growth, abundance, or distribution of the population of a species in an ecosystem. |
| limiting factor principle | Too much or too little of any abiotic factor can limit or prevent growth of a population of a species in an ecosystem, even if all other factors are at or near the optimal range of tolerance for the species. |
| logistic growth | Pattern in which exponential population growth occurs when the population is small, and population growth decreases steadily with time as the population approaches the carrying capacity. |
| mature community | Fairly stable, self–sustaining community in an advanced stage of ecological succession; usually has a diverse array of species and ecological niches; captures and uses energy and cycles critical chemicals more efficiently than simpler, immature communities. |
| mutualism | Type of species interaction in which both participating species generally benefit. |
| parasite | Consumer organism that lives on or in, and feeds on, a living plant or animal, known as the host, over an extended period. |
| parasitism | Interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host |
| perennial | Plant that can live for more than 2 years. |
| pioneer community | First integrated set of plants, animals, and decomposers found in an area undergoing primary ecological succession. |
| pioneer species | First hardy species—often microbes, mosses, and lichens—that begin colonizing a site as the first stage of ecological succession. |
| population | Group of individual organisms of the same species living in a particular area. |
| population crash | Dieback of a population that has used up its supply of resources, exceeding the carrying capacity of its environment. |
| population density | Number of organisms in a particular population found in a specified area or volume. |
| population dispersion | General pattern in which the members of a population are arranged throughout its habitat. |
| population dynamics | Major abiotic and biotic factors that tend to increase or decrease the population size and affect the age and sex composition of a species. |
| population size | Number of individuals making up a population’s gene pool. |
| predation | Interaction in which an organism of one species captures and feeds on some or all parts of an organism of another species. |
| predator | Organism that captures and feeds on some or all parts of an organism of another species |
| predator–prey relationship | Relationship that has evolved between two organisms, in which one organism has become the prey for the other, the latter called the predator. |
| prey | Organism that is killed by an organism of another species and serves as its source of food. |
| primary ecological succession | Ecological succession in a area without soil or bottom sediments |
| principles of sustainability | Principles by which nature has sustained itself for billions of years by relying on solar energy, biodiversity, and nutrient recycling. |
| range of tolerance | Range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. |
| reproduction | Production of offspring by one or more parents. |
| reproductive potential | Another term for biotic potential. |
| resource partitioning | Process of dividing up resources in an ecosystem so that species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places. |
| restoration ecology | Research and scientific study devoted to restoring, repairing, and reconstructing damaged ecosystems. |
| S–shaped curve | Leveling off of an exponential, J–shaped curve when a rapidly growing population reaches or exceeds the carrying capacity of its environment and ceases to grow. |
| salinity | Amount of various salts dissolved in a given volume of water. |
| secondary ecological succession | Ecological succession in an area in which natural vegetation has been removed or destroyed but the soil or bottom sediment has not been destroyed. |
| sexual reproduction | Reproduction in organisms that produce offspring by combining sex cells or gametes (such as ovum and sperm) from both parents. It produces offspring that have combinations of traits from their parents. |
| succession | The order in which the biotic and abiotic factors of a community are established. |
| population distribution | Variation of population density over a particular geographic area or volume. For example, a country has a high population density in its urban areas and a much lower population density in its rural areas. |
