| Glossary | Ch01 Ch02 Ch03 Ch04 Ch05 Ch06 Ch07 Ch08 Ch09 Ch10 Ch11 Ch12 Ch13 Ch14 |
| Chapter 3 | |
| abstract expressionism | An American movement in the field of painting that began in the late forties and emphasized a nonrepresentational style. The movement broke into two branches: action painting and color field painting. |
| adaptation | Any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions. It usually results from a beneficial mutation. See biological evolution, differential reproduction, mutation, natural selection. |
| adaptive radiation | Process in which numerous new species evolve to fill vacant and new ecological niches in changed environments, usually after a mass extinction or mass depletion. Typically, this takes millions of years. |
| adaptive trait | See adaptation. |
| allele | Slightly different molecular form found in a particular gene. |
| altitude | Height above sea level. Compare latitude. |
| ancient forest | See old-growth forest. |
| aquatic | Pertaining to water. Compare terrestrial. |
| aquatic life zone | Marine and freshwater portions of the biosphere. Examples include freshwater life zones (such as lakes and streams) and ocean or marine life zones (such as estuaries, coastlines, coral reefs, and the deep ocean). |
| arid | Dry. A desert or other area with an arid climate that has little precipitation. |
| artificial selection | Process by which humans select one or more desirable genetic traits in the population of a plant or animal and then use selective breeding to end up with populations of the species containing large numbers of individuals with the desired traits. Compare genetic engineering, natural selection. |
| 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. Compare sexual reproduction. |
| background extinction | Normal extinction of various species as a result of changes in local environmental conditions. Compare mass depletion, mass extinction. |
| biological evolution | Change in the genetic makeup of a population of a species in successive generations. If continued long enough, it can lead to the formation of a new species. Note that populations--not individuals--evolve. See also adaptation, differential reproduction, natural selection, theory of evolution. |
| biome | Terrestrial regions inhabited by certain types of life, especially vegetation. Examples are various types of deserts, grasslands, and forests. |
| biotic potential | Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth. See environmental resistance. |
| broadleaf deciduous plants | Plants such as oak and maple trees that survive drought and cold by shedding their leaves and becoming dormant. Compare broadleaf evergreen plants, coniferous evergreen plants. |
| broadleaf evergreen plants | Plants that keep most of their broad leaves year round. Examples are the trees found in the canopies of tropical rain forests. Compare broadleaf deciduous plants, coniferous evergreen plants. |
| carrying capacity (K) | Maximum population of a particular species that a given habitat can support over a given period of time. See dieback. |
| chemical evolution | Formation of the earth and its early crust and atmosphere, evolution of the biological molecules necessary for life, and evolution of systems of chemical reactions needed to produce the first living cells. These processes are believed to have occurred about 1 billion years before biological evolution. Compare biological evolution. |
| climate | Physical properties of the troposphere of an area based on analysis of its weather records over a long period (at least 30 years). The two main factors determining an area's climate are temperature, with its seasonal variations, and the amount and distribution of precipitation. Compare weather. |
| coastal wetland | Land along a coastline, extending inland from an estuary, that is covered with salt water all or part of the year. Examples are marshes, bays, lagoons, tidal flats, and mangrove swamps. Compare inland wetland. |
| coastal zone | Warm, nutrient-rich, shallow part of the ocean that extends from the high-tide mark on land to the edge of a shelflike extension of continental land masses known as the continental shelf. Compare open sea. |
| coevolution | Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo various adaptations. See evolution, natural selection. |
| coniferous evergreen plants | Cone-bearing plants (such as spruces, pines, and firs) that keep some of their narrow, pointed leaves (needles) all year. Compare broadleaf deciduous plants, broadleaf evergreen plants. |
| coniferous trees | Cone-bearing trees, mostly evergreens, that have needle-shaped or scalelike leaves. They produce wood known commercially as softwood. Compare deciduous plants. |
| constancy | Ability of a living system, such as a population, to maintain a certain size. See homeostasis. Compare inertia, resilience. |
| coral reef | Formation produced by massive colonies containing billions of tiny coral animals, called polyps, that secrete a stony substance (calcium carbonate) around themselves for protection. When the corals die, their empty outer skeletons form layers and cause the reef to grow. They are found in the coastal zones of warm tropical and subtropical oceans. |
| deciduous plants | Trees, such as oaks and maples, and other plants that survive during dry seasons or cold seasons by shedding their leaves. Compare coniferous trees, succulent plants. |
| desert | Biome in which evaporation exceeds precipitation and the average amount of precipitation is less than 25 centimeters (10 inches) a year. Such areas have little vegetation or have widely spaced, mostly low vegetation. Compare forest, grassland. |
| dieback | Sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat. See carrying capacity. |
| differential reproduction | Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits. See natural selection. |
| doubling time | Time it takes (usually in years) for the quantity of something growing exponentially to double. It can be calculated by dividing the annual percentage growth rate into 70. See rule of 70. |
| drainage basin | See watershed. |
| ecological niche | Total way of life or role of a species in an ecosystem. It includes all physical, chemical, and biological conditions a species needs to live and reproduce in an ecosystem. See fundamental niche, realized niche. |
| ecological population density | Number of individuals of a population per unit area of habitat. Compare population density. |
| ecotone | Transitional zone in which one type of ecosystem tends to merge with another ecosystem. See edge effect. |
| edge effect | Existence of a greater number of species and a higher population density in a transition zone (ecotone) between two ecosystems than in either adjacent ecosystem. See ecotone. |
| environmental resistance | All the limiting factors that act together to limit the growth of a population. See biotic potential, limiting factor. |
| estuary | Partially enclosed coastal area at the mouth of a river where its fresh water, carrying fertile silt and runoff from the land, mixes with salty seawater. |
| euphotic zone | Upper layer of a body of water through which sunlight can penetrate and support photosynthesis. |
| eutrophic lake | Lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates. Compare mesotrophic lake, oligotrophic lake. |
| evergreen plants | Plants that keep some of their leaves or needles throughout the year. Examples are ferns and cone-bearing trees (conifers) such as firs, spruces, pines, redwoods, and sequoias. Compare deciduous plants, succulent plants. |
| evolution | See biological evolution. |
| exponential growth | Growth in which some quantity, such as population size or economic output, increases by a fixed percentage of the whole in a given time period; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter J. Compare linear growth. |
| extinction | Complete disappearance of a species from the earth. This happens when a species cannot adapt and successfully reproduce under new environmental conditions or when it evolves into one or more new species. See also endangered species, mass depletion, mass extinction, threatened species. Compare speciation. |
| forest | Biome with enough average annual precipitation (at least 76 centimeters, or 30 inches) to support growth of various tree species and smaller forms of vegetation. Compare desert, grassland. |
| freshwater life zones | Aquatic systems where water with a dissolved salt concentration of less than 1% by volume accumulates on or flows through the surfaces of terrestrial biomes. Examples are (1) standing (lentic) bodies of fresh water such as lakes, ponds, and inland wetlands and (2) flowing (lotic) systems such as streams and rivers. Compare biome. |
| fundamental niche | The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species. See ecological niche. Compare realized niche. |
| gene flow | Movement of genes between populations, which can lead to changes in the genetic composition of local populations. |
| gene mutation | See mutation. |
| gene pool | Sum total of all genes found in the individuals of the population of a particular species. |
| generalist species | Species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Examples are flies, cockroaches, mice, rats, and human beings. Compare specialist species. |
| genetic adaptation | Changes in the genetic makeup of organisms of a species that allow the species to reproduce and gain a competitive advantage under changed environmental conditions. See differential reproduction, evolution, mutation, natural selection. |
| genome | Complete set of genetic information for an organism. |
| geographic isolation | Separation of populations of a species for long times into different areas. |
| grassland | Biome found in regions where moderate annual average precipitation (25-76 centimeters, or 10-30 inches) is enough to support the growth of grass and small plants but not enough to support large stands of trees. Compare desert, forest. |
| habitat | Place or type of place where an organism or population of organisms lives. Compare ecological niche. |
| inertia | Ability of a living system to resist being disturbed or altered. Compare constancy, resilience. |
| inland wetland | Land away from the coast, such as a swamp, marsh, or bog, that is covered all or part of the time with fresh water. Compare coastal wetland. |
| intertidal zone | Area of shoreline between low and high tides. |
| intrinsic rate of increase (r) | Rate at which a population could grow if it had unlimited resources. Compare environmental resistance. |
| invertebrates | Animals that have no backbones. Compare vertebrates. |
| K-selected species | Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age. Compare r-selected species. |
| K-strategists | See K-selected species. |
| lake | Large natural body of standing fresh water formed when water from precipitation, land runoff, or groundwater flow fills a depression in the earth created by (1) glaciation, (2) earth movement, (3) volcanic activity, or (4) a giant meteorite. See eutrophic lake, mesotrophic lake, oligotrophic lake. |
| latitude | Distance from the equator. Compare altitude. |
| linear growth | Growth in which a quantity increases by some fixed amount during each unit of time. Compare exponential growth. |
| 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. See S-shaped curve. Compare J-shaped curve. |
| macroevolution | Long-term, large-scale evolutionary changes among groups of species. Compare microevolution. |
| mangrove swamps | Swamps found on the coastlines in warm tropical climates. They are dominated by mangrove trees, any of about 55 species of trees and shrubs that can live partly submerged in the salty environment of coastal swamps. |
| mass depletion | Period of species loss in which extinction rates are much higher than normal but not high enough to classify as a mass extinction. Compare background, extinction, mass extinction. |
| mass extinction | Catastrophic, widespread, often global event in which major groups of species are wiped out over a short time compared with normal (background) extinctions. Compare background extinction, mass depletion. |
| mesotrophic lake | Lake with a moderate supply of plant nutrients. Compare eutrophic lake, oligotrophic lake. |
| microevolution | Small genetic changes a population undergoes. Compare macroevolution. |
| minimum dynamic area (MDA) | Minimum area of suitable habitat needed to maintain the minimum viable population. See minimum viable population. |
| minimum viable population (MVP) | Estimate of the smallest number of individuals necessary to ensure the survival of a population in a region for a specified time period, typically ranging from decades to 100 years. |
| mutagen | Chemical or form of radiation that causes inheritable changes (mutations) in the DNA molecules in the genes found in chromosomes. See carcinogen, mutation, teratogen. |
| mutation | Random change in DNA molecules making up genes that can yield changes in anatomy, physiology, or behavior in offspring. See mutagen. |
| natural rate of extinction | See background extinction. |
| natural selection | Process by which a particular beneficial gene (or set of genes) is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions. See adaptation, biological evolution, differential reproduction, mutation. |
| nekton | Strongly swimming organisms found in aquatic systems. Compare benthos, plankton. |
| niche | See ecological niche. |
| old-growth forest | Virgin and old, second-growth forests containing trees that are often hundreds, sometimes thousands of years old. Examples include forests of Douglas fir, western hemlock, giant sequoia, and coastal redwoods in the western United States. Compare second-growth forest, tree plantation. |
| oligotrophic lake | Lake with a low supply of plant nutrients. Compare eutrophic lake, mesotrophic lake. |
| open sea | Part of an ocean that is beyond the continental shelf. Compare coastal zone. |
| plankton | Small plant organisms (phytoplankton) and animal organisms (zooplankton) that float in aquatic ecosystems. |
| 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 distribution | Variation of population density over a particular geographic area. For example, a country has a high population density in its urban areas and a much lower population density in rural areas. |
| population dynamics | Major abiotic and biotic factors that tend to increase or decrease the population size and age and sex composition of a species. |
| population size | Number of individuals making up a population's gene pool. |
| population viability analysis (PVA) | Use of mathematical models to estimate a population's risk of extinction. See minimum viable population. |
| r-selected species | Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period of time. Compare K-selected species. |
| r-strategists | See r-selected species. |
| realized niche | Parts of the fundamental niche of a species that are actually used by that species. See ecological niche, fundamental niche. |
| reproduction | Production of offspring by one or more parents. |
| reproductive isolation | Long-term geographic separation of members of a particular sexually reproducing species. |
| reproductive potential | See biotic potential. |
| resilience | Ability of a living system to restore itself to original condition after being exposed to an outside disturbance that is not too drastic. See constancy, inertia. |
| runoff | Fresh water from precipitation and melting ice that flows on the earth's surface into nearby streams, lakes, wetlands, and reservoirs. See reliable runoff, surface runoff, surface water. Compare groundwater. |
| S-shaped curve | Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow. |
| sexual reproduction | Reproduction in organisms that produce offspring by combining sex cells, or gametes (such as ovum and sperm), from both parents. This produces offspring that have combinations of traits from their parents. Compare asexual reproduction. |
| specialist species | Species with a narrow ecological niche. They may be able to (1) live in only one type of habitat, (2) tolerate only a narrow range of climatic and other environmental conditions, or (3) use only one type or a few types of food. Compare generalist species. |
| speciation | Formation of two species from one species because of divergent natural selection in response to changes in environmental conditions; usually takes thousands of years. Compare extinction. |
| species equilibrium model | See theory of island biogeography. |
| succulent plants | Plants, such as desert cacti, that survive in dry climates by having no leaves, thus reducing the loss of scarce water. They store water and use sunlight to produce the food they need in the thick, fleshy tissue of their green stems and branches. Compare deciduous plants, evergreen plants. |
| surface water | Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation or transpiration. See runoff. Compare groundwater. |
| survivorship curve | Graph showing the number of survivors in different age groups for a particular species. |
| terrestrial | Pertaining to land. Compare aquatic. |
| territoriality | Process in which organisms patrol or mark an area around their home, nesting, or major feeding site and defend it against members of their own species. |
| theory of evolution | Widely accepted scientific idea that all life-forms developed from earlier life-forms. Although this theory conflicts with the creation stories of many religions, it is the way biologists explain how life has changed over the past 3.6-3.8 billion years and why it is so diverse today. |
| theory of island biogeography | The number of species found on an island is determined by a balance between two factors: the (1) immigration rate (of species new to the island) from other inhabited areas and (2) extinction rate (of species established on the island). The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity). |
| tree farm | See tree plantation. |
| vertebrates | Animals that have backbones. Compare invertebrates. |
| watershed | Land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river). |