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127 Cards in this Set
- Front
- Back
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in ecology, researchers work at four main levels
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1. organisms, 2. populations, 3. communities, and 4. ecosystems.
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community
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groups of species that interact with each other within a particular area.
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ecosystem
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all the organisms in particular region along with nonliving components
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productivity
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total amount of carbon fixed by photosynthesis per unit area per year, and light has major influence on this
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Lakes and Ponds
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freshwater, ponds are small and lakes are big enough that water can be mixed by wind and wave action. Water movement driven by wind and temperature. Plankton, composing of cyanobacteria, algae, and other microscopic organism live in photic zone, and fish that eat them. Animals that eat dead organic matter or detritus are in benthic zone.
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5 zones in lakes
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littoral zone consists of shallow waters along the shore, where flowering plants are rooted. limnetic zone is offshore and comprises water that receives enough light to support photo. benthic zone is made up of the substrate. littoral, limnetic, and benthic zones that receive sunlight are part of photic zone. aphotic zone does not receive light.
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turnovers
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norther and temperate regions of world experiences during spring and fall. it occurs in response to changes in air temperature. in winter, water at surface is locked up in ice, and water just under is a little warmer and has a lot of oxygen. water at bottom is warmer, and has less oxygen (decomposing organic matter use oxygen). ice melts in spring, and water temp rises til 4 degrees, at highest density of water. water at top of heavier, so it sinks.
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thermocline
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"heat slope" and thermal stratification
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wetlands
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shallow-water habitats where soil is saturated with water for at lease part of the year. they have only shallow water, they have EMERGENT VEGETATION - plants that grow above surface of water. most water has light. Marshes and swamps have slow steady flow of water. BOGS develop in depression where water flow is low or nonexistent. oxygen is used up during decomposition of dead organic matter faster than it enters via diffusion from atmosphere. bog is oxygen poor and anoxic. decomposition slow, acids build up, nitrogen becomes unavailable for plants. MARSHES lack trees and feature grasses, SWAMPS have trees and shrubs.
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streams
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bodies of water that move constantly in one direction. creeks are small, rivers are large. variable in streams are speed of current and availability of oxygen and nutrients. Filled with sunlight. At top of mountain glacier, it's colder, narrower and faster. Oxygen higher in fast moving streams because water droplets are exposed to atmosphere when moving water splashes over rocks and obstacles. Cold water has more oxygen. No photo organisms at top of mountain. Some species can live in fast moving streams. When streams are are wide and slow, conditions are better for growth of algae and plants, nutrients increase. Top: fast, cold, nutrient poor, oxygenated.
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Estuaries
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where river meets ocean. fresh and salt water mix. saline marshes, water moving in and out. salinity varies with changes in river flows and proximity to ocean. salinity effects osmosis and water balance. species have adaptations to live in salinity. Shallow enough to have sunlight, but water depth fluctuate dramatically due to tides, storms, and floods. water flow fluctuates daily and seasonally, imp because it alters salinity, and affect organisms. very productive environment, many young fish, feed on vegetation and plankton while hiding from predators.
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6 different zones of ocean
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INTERTIDAL: "between tides" consists of a rocky, sandy, or muddy beach that is exposed to the air at low tide but submerged at high tide, NERITIC zone extends from intertidal zone to depths of 200 m. outermost edge is defined b end of the CONTINENTAL SHELF-gently sloping submerged portion of continental plate. OCEANIC ZONE: "open ocean", deepwater region beyond the continental shelf. BENTHIC ZONE. PHOTIC ZONE: intertidal and sunlit regions of the neritic, oceanic, and benthic zones. APHOTIC ZONE: areas that do not receive sunlight.
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ocean
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water movement different in different depths. in intertidal zone, tides and wave action are the major influences, in neritic zone, currents that bring nutrient-rich water from the benthic zone of deep ocean toward shore have a heavy impact. nutrient rich water comes to surface when it hits steep slope of continental plate. large-scale currents circulate water in oceanic zone in response to prevailing winds and earth's rotation. high productivity in in intertidal zone because of sunlight and nutrients from estuaries. also in neritic zone due to nutrients contributed by upwellings at edge of continental plate. fisheries in neritic. CORAL REEFS in shallow neritic zone in tropics. no nutrients in open ocean, but there's light. dead bodies drift downward and are lost.
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biomes
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major groupings of plant and animal communities defined by dominant vegetation type.
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climate
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prevailing, long-term weather conditions found in an area, while WEATHER consists of specific short term atmospheric conditions of temperature, moisture, sunlight, and wind.
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4 components of climate
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temperature: enzymes that make life possible work at optimal efficiency in narrow range of temp. affects availability of moisture. moisture is imp because it's required for life, and terrestrial organisms constantly lose water to the environment through evaporation or transpiration. sunlight: required for photosynthesis. wind: exacerbates the effects of tempearture and moisture, wind increases heat loss due to evaporation and convection and increases water loss. direct physical impact on birds, insects, and plants.
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nature of biome is controlled by this
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1. average annual temperature and precipitation. 2. annual variation in temperature and precipitation.
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NPP
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net primary productivity, total amount of carbon that is fixed per year minus amount of fixed carbon oxidized during cellular respiration. fixed carbon that is consumed by respiration provides energy for organism but is not used for growth, or production of BIOMASS. NPP is imp because it represents organic matter that is available as food for other organisms
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aboveground biomass
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total mass of living plants, excluding roots.
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tropical wet forest
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equatorial regions, broad leaves, evergreen, older leaves are shed throughout year. 25-30 degrees, no seasonal variation in temp. a lot of rain, 2 inches in driest month. high productivity, aboveground biomass. species diversity. distinctive CANOPY: uppermost layers of branches. complex assortment of vines, EPIPHYTES (plants that grow entirely on other plants) ,small trees, shrubs, and herbs.
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subtropical deserts
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found throughout the world in two locations, 30 degrees latitude north and south. temp vary more than tropical climate, but temperatures still never fall below freezing (usually). low precipitation. not adequate for photo, productivity is tiny. spaced plants, competition for water. plants adapt by... growing at low rate year-round, or breaking dormancy and growing rapidly in response to any rainfall. small leaves or no leaves, thick, waxy coating on leaves and stems, and CAM pathway for photo.
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temperate grasslands
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central N America and heartland of Eurasia. (prairies, steppes). region is TEMPERATE if it has pronounced annual fluctuations in temperature, hot summers and cold winters. temperature variation is important because it dictates a well-defined growing season. grasses dominant for two reasons: 1. conditions are too dry to enable tree growth, or 2. encroaching trees are burned out by fires (by lightning or native people managing land for game animals). grassland soils are fertile, packed with roots and rhizomes, which add organic material to soil as they die and decay. retain nutrients, because rainfall is low enough to keep key ions from dissolving and leaching out of soil.
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temperate forests
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comes from temperate areas with high precipitation. most common in N america, western europe, east asia, chile, and new zealand. monthly temp fall below freezing and plant growth stops. precipitation is moderately high, and constant. many deciduous species, dry leaves in autumn and grow new leaves in spring. moderate diversity.
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boreal forests
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same as TAIGA in canada, alaska, russia, and northern Europe. cold winters, and cool short summers. temperature variation is extreme, sometimes 70 degrees celsius. low precipitation, but evaporation is low, so moisture is abundant for trees. dominated by highly cold-tolerate conifers. evergreen. they can begin photo early in spring, even before snow melts, when sunshine is intense enough to warm needles. maybe it's because soils tend to be acidic and contain little nitrogen. leaves are nitrogen rich, species must produce new set of leaves each year might be at disadvantage. low productivity, aboveground biomass is high, because slow-growing trees live long and accumulate. low species diversity.
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arctic tundra
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poles. growing season is 6-8 weeks, and other times are freezing. low precipitation, but low evaporation, so soils are saturated year-round. treeless. short summer, cool, wind damage. woody shrubs are common, but they're short. low species diversity, low productivity, low aboveground biomass. soils are permanently frozen, PERMAFROST. low tempeartures inhibit both release of nutrients from decaying organic matte and uptake of nutrients into live roots. covered with plants or lichens.
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hadley cell
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air is heated by strong sunlight along equator expands and rises. warm air can hold a great deal of moisture, because warm water molecules tend to stay in vapor form instead of condensing into droplets. it expands into larger volume of upper atmosphere, which lowers its density and temperature, known as adiabatic cooling. rising air cools, ability to hold water declines. precipitation at equator. air is heated, and cooler "older" air above earth's surface is pushed poleward. when it cooled enough, density increases and sinks, and it absorbs more and more solar radiation reflected from earth's surface and begins to warm, and gains water-holding capacity. it holds on to its water and little rain occurs at deserts.
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mountains and ocean
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affect climate: west coast, winds from west with moisture. as it begin to rise over mountains, air cools and releases large volumes of water as rain. after mountain, it is dry because moisture has been released. areas in this dry air are said to be in a RAIN SHADOW.
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effects of ocean on climates
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water has extremely high specific heat, it has large capacity for storing heat energy. this moisture can absorb heat from atmosphere in summer, when water tempeature is cooler than air temperature. ocean moderates summer temperatures on nearby landmasses. it releases heat to atmosphere in winter, when water temperature is warmer than air temperature.
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studies to predict how global warming will affect aquatic and terrestrial ecosystems.
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1. simulation studies: based on computer models of weather patterns in local regions. by increasing average tempeartures in these modles, researchers can predict how wind and rainfall patterns, storm frequency and intensity and other aspects of weather and climate will change. 2. observational studies, based on long-term monitoring at fixed sites around the globe. document changes in key physical variables, water depth, water flow, temperature, and precipitation, as well as changes in the distribution and abundance of organisms. by extrapolation, they can predict these changes. 3. experiments are designed to simulate changed climate conditions, and to record responses by the organisms present.
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effect of increase in average global temperature
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increasing variability in temperature and precipitation. global warming is making climates more extreme.
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biogeography
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study of how organisms are distributed geographically.
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range
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most fundamental observation, about geographic distribution of species. no one species can survive the full range of environmental conditions present on earth. because of fitness trade-offs, organisms tend to be adapted to a limited set of physical conditions.
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dispersal
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movement of an individual from place of its birth, hatching, to origin to the location where it lives and breeds as an adult. this decides what species live in what area, and physical barriers contribute to this.
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exotic species
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one that is not native, introduced in new area, and it may spread rapidly, and eliminate native species, it is said to be INVASIVE species.
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proximate causation
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mechanistic, explains how actions occur in terms of neurological, hormonal, and skeletal-muscular mechanisms involved.
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ultimate causation
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evolutionary, explains why actions occur - based on their evolutionary consequences and history. is particular behavior adaptive, it increases in individual's fitness? how does it help? (proximate and ultimate are complementary, goes hand and hand)
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learning
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change in behavior that results from a specific experience in the life on an individual.
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fixed action patterns
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FAPS, stereotyped, meaning they are performed in the same way every time, and are triggered by simple stimuli called RELEASERS or SIGN STIMULI.
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innate behavior
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FAPS are examples of this, behavior that is inherited and shows little variation based on learning or the individual's condition. innate behavior is common when 1. situations that have a high impact on fitness and demands a reflex-like, unlearned response, or 2. situations where learning is not possible. (web weaving in spiders, next building in birds.) innate behavior is possessed by all species, but many more behaviors are changed by learning and show flexibility in response to changing environmental changes. animals make choices. they weigh benefits and costs of responding in various ways.
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optimal foraging
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animals should maximize their feeding efficiency. maximize usable energy, given costs of finding and ingesting their food and risk of being eaten while they're at it.
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size-advantage hypothesis
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states that if a group of fish is living in a territory dominated by a single male, and if that male dies, then the largest female should switch from female to male. based on observation that fish habe indeterminate growth, meaning they continue growing thorughout their lives.
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classical conditioning
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individuals are trained by experience to give the same response to more than one stimulus, even a stimulus that has nothing to do with the normal response
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imprinting
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upon hatching, ducklings and goslings adopt as their mother the first moving thing they see. some geese imprint on whatever boots he was wearing at the time, and some ducklings would imprint on him only if he crawled on all fours and quacked continuously. fast, irreversible, and occurs during a critical period... it is not typical of most types of learning.
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ctirical period
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imprinting occurs during this period, in the early life of the animal.
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white-crowned sparrows
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heavily influenced by learning. learning is constrained to certain periods of life and occurs only in response to certain types of stimuli. variation exists in song-learning ability and in the size of song repertoires.
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cognition
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recognition and manipulation of facts about the world, combined with the ability to form concepts and gain insignts. the results cannot be observed directly. researchers must design experimental situations that require animals to manipulate facts or information and demonstrate an ability to form novel associations or insights. crows can think
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adaptive significance of learning
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learning depends on the environment of where the species life. mice living in pipes and eat trash can go through mazes well and can distinguish poisonous food. mice in dirt can remember where they hid their food and can think to steel others' foods.
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echolocation
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by bats, to find insects int he dark. they emit high-pitched pulses of sound and listen for the echo.
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communication
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any process in which a signal from one individual modifies the behavior of a recipient individual. a SIGNAL is any information-containing behavior. it's a crucial component of animal behavior, because it creates a stimulus that elicits a response.
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types of communication
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varies with its habitat. sounds in water, because it's not dispelled quickly. several modes of communication used in conjunction (red-winged blackbird with model and speakers). advantages and disadvantages.
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deceit
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only works when it is rare. when it's common, natural selection will favor individuals that can detect and avoid or punish liars. but if liars are rare, then natural selection will favor individuals that are occasionally fooled by are more commonly rewarded by responding to signals in a normal way.
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orientation
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movement that results in a change of position, like the flight paths of hunting bats, escaping moths and foraging bees.
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taxis
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simple foraging, involves positioning the body, or part of the body, toward or away form a stimulus.
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phototaxis
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a moth attracted to a porchlight.
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phonotaxis
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female cricket approaching a calling male, toward sound. (negative phonotaxis: retreat from siren blaring)
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migration
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long-distance movement of a population associated with a change of seasons
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how animals find their way
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PILOTING: use of familiar landmarks, COMPASS ORIENTATION: movement that is oriented in a specific direction - use sun and starts. , TRUE NAVIGATION: ability to locate a specific place on earth's surface.
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circadian clock
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internal clock, maintaining a 24-hour rhythm of chemical activity. set by light-dark transitions of day and night, and it tells individuals enough about the time of day that they can use the Sun's position to find magnetic north. orient also using magnetic field. (birds probably have multiple compasses).
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altruism
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behavior that has a fitness cost to the individual exhibiting the behavior and a fitness benefit to the recipient of the behavior. C: altruistic actor, B benefit. allele could spread if Br>C, where r is the COEFFICIENT OF RELATEDNESS. (fraction of alleles in the actor and beneficiary that are identical by descent)
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hamilton's rule
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individuals can pass their alleles on to the next generation not only by having their own offspring by also by helping close relatives produce more offspring.
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kin selection
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natural selection that acts through benefits to relatives.
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reciprocal altruism
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exchange of fitness benefits that are separated in time. if someone helped them before, they'll probably help them back regardless of if they're related or not.
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demography
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analyzing birth rates, death rates, immigration rates, and emigration rates are all part of this, the study of factors that determine the size and structure of populations through time.
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generation
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average time between a mother's first offspring and her daughter's first offspring
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life table
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summarizes the probability that an individual will survive and reproduce in any given time interval over the course of its lifetime.
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survivorship
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key component of a life table and is defined as the proportion of offspring produced that survive, on average, to a particular age.
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cohort
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a group of individuals of the same age that can be followed through time. (if survivorship from birth to age 2 was .308, that means an average of 308 female lizards would survive for two years.
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survivorship curve
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resulting graph to recognize general patterns in survivorship and make comparisons among populations or species, biologists plot the logarithm of the number of survivors versus age. type I: most species reach maximum life span (humans), type II: relatively constant mortality throughout their lives once they leave nest (songbirds), and type III: high death rates at the beginning. survivorship curves pinpoint the stag of life when endangered species have particularly low survivorship. then biologists can protect them at that stage in life.
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fecundity
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number of female offspring produced by each female in the population
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age-specific fecundity
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average number of female offspring produced by a female in age class x.
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age class
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group of individuals of a specific age, like if female lizards between four and five years old. data on survivorship and fecundity allow researchers to calculate growth rate of a population.
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net reproductive rate
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growth rate of a population per generation. it is sum of survivorship at an age class times age specific fecundity.
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fitness trade-offs
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high fecundity and high survival are not both possible because of this. every individual has restricted amount of time and energy at its disposal, meaning their resources are limited.
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life history
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how an individual allocates resources to growth, reproduction, and activities or structures that are related to survival.
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per-capita rate of increase
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symbolized r, is the difference between the birth rate and death rate per individual. a population's growth rate is change in number of individuals in population (delta N) per unit time (delta t). if no immigration or emigration is occurring, then growth rate is equal to number of individuals (N) in population times difference between birth rate per individual (b) and death rates per individual (d). it is useful for growth rate because it is independent of geneartion time and is relevant for speices that breed either seasonally or continuously.
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intrinsic rate of increase
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r max. happens when birth rates per individual are high as possible and death rates are low as possible. when this happens, population's growth rate is delta N/delta t = r maxN. each species has r max that does not change.
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exponential population growth
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when r does not change over time. growth rate does not depend on the number of individuals in the population. biologists say this type of population growth is DENSITY INDEPENDENT. exponential growth adds an increasing number of individuals as the total number of individuals, N, gets larger. r of 0.02 will add more individuals in a larger population than a smaller one. in nature, exponential population growth happens when few individuals found a new population in a new habitat or when a population hs been devastated by a storm or some other type of catastrophe and then begins to recover, starting with a few surviving individuals. exponential growth cannot continue indefinitely. growth is usually density dependent, hits carrying capacity
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carrying capacity
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K, defined as maximum number of individuals in a population that can be supported in a particular habitat over a sustained period of time. it depends on large number of factors: food, space, water, soil quality, resting or nesting sites, and intensity of disease and predation. it can change from year to year, depending on conditions.
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logistic population growth
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changes in growth rate that occur as function of population size. density dependent.
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finite rate of increase
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when N1/N0 = lamda. lamda is this. it is growth rate.
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population dynamics
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changes in populations through time, it has uncovered a wide array of patterns in natural populations in addition to exponential logistic growth.
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metapopulation
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population of populations. because humans are reducing large, continuous areas of forest and grasslands to isolated patches or reserves, more and more species are being forced into a metapopulation structure.
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population cycles
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regular fluctuations in size that some animal populations exhibit
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age structure
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proportion of individual that are at each possible age. it has dramatic influence on population's growth over time. primrose: 1. populations that are dominated by juveniles should experience rapid growth. but after a while, goes down because of shading. 2. dependent on windstorms that knock down trees and create sunlit gaps. governed by abiotic, density-independent factor. 3. large population, large number of subpopulations, each found in canopy gaps. each will arise, grow, and go extinct over time.
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zpg
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zero population growth, when r = 0 and there's replacement rate.
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population viability analysis (PVA)
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model that estimates the likelihood that a population will avoid extenction for a given time period. it attempts to combine basic demographic models for a species with data on geographic structure and the rate and severity of habitat disturbance.
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coevolution
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species influence each others' evolution, leading to reciprocal adaptation. lead to long-term changes in the characteristics of populations.
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6 different aspects of interspecific competition (competition between different species)
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1. consumptive competition: individuals consume same resources. 2. preemptive competition: one species makes space unavailable to other species. 3. overgrowth competition happens when one species grows above another. 4. chemical competition when one species produces toxins that negatively affect another. 5. territorial competition: when mobile species protects its feeding or breeding territory against other species, and 6. encounter competition: two species interfere directly for access to specific resources.
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niche
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range of resources that the species is able to use or range of conditions it can tolerate. interspecific competition occurs when niches of two species overlap.
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competitive exclusion principle
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GF Gause claimed it isn't possible for species with the same niche to coexist. ASYMMETRIC COMPETION: one species suffers a much greater fitness decline than the other species. SYMMETRIC COMPETITION: each of interacting species experiences equal decrease in fitness.
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fundamental niche
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combination of resources or areas used or conditions tolerated in the absense of competitors, and it's REALIZED NICHE, which is portion of resources or areas used or conditions tolerated when competition occurs.
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niche differentiation
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change in resource to avoid competition and reduce amount of niche overlap. the change in species' traits is called CHARACTER DISPLACEMENT.
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standing or constitutive defenses
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always present, like sharp spines, kicking hooves, schooling and flocking behavior...
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mimicry
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one species closely resembles another species to look like another dangerous species. when harmful prey species resemble each other, MULLERIAN MIMICRY is said to occur. BATESIAN mimicry is when harmless species look like dangerous species.
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inducible defenses
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defensive traits produced only in response to presence of a predator. it declines if predators leave the habitat. they're efficient energetically, but they are slow, it takes time to produce them.
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meta-analysis
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study of studies, meaning an analysis of a large number of data sets on a particular question.
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1. top-down control hypothesis
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one of reasons why world is still green: herbivore populations are limited by predation and disease. predators and parasites remove herbivores that eat plants "top-down" of food chain.
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2. poor-nutrition hypothesis
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plants are a poor food source in terms of nutrients they provide for herbivores. plants only have 10% of nitrogen in animals. herbivores could eat more plants, but at a cost of being seen by predators and expend energy processing food.
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3. plant-defense hypothesis
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plants defend themselves effectively enough to limit herbivory. thorns, prickles, hairs, poisons, etc. animals can't digest cellulose or lignin without help form protists or bacteria.
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climax community
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stable final stage in development of communities. nature of climax community is determined by the area's climate and does no change over time. part of idea of Clements, that stated communities develop passing through a series of predictable stages. Gleason said community is neither stable nor predictable.
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impact of disturbance
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1. type of disturbance, 2. its frequency, and 3. its severity. biologists refer to a community's DISTURBANCE REGIME.
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succession
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recovery that follows severe disturbances. PRIMARY SUCCESSION: when disturbance removes soil and its organisms as well as organisms that live above the surface. (glaciers, floods, volcanic eruptions, landslides) SECONDARY SUCCESSION: disturbance removes some or all of organisms from an area but leaves the soil intact. (fire and logging)
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pioneering species
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"weedy" life histories when organisms arrive, and endure harsh environmental conditions. a WEED is a plant that is adapted for growth in disturbed sil. most of their energy to reproduction and little to competitive ability.
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three effects of subsequent species
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1. FACILITATION: when presence of an early arriving species makes conditions more favorable for arrival of certain later species by providing shade or nutrients. 2. TOLDERANCE: existing species do not affect the probability that subsequent species will become established. INHIBITION occurs wen the presence of one species inhibits the establishment of another. Glacier bay Alaska: 1. lower part of bay, Sitka spruce began growing and quickly formed desnse forests. 2. middle-aged sites in upper part of the bay, alder thickets were dominant for several decades, spruce just beginning to become common. 3. youngest sites have alder thickets, spruce trees scarce. cottonwood
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species richness
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simple count of how man species are present in a given community
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species diversity
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weighted measure that incorporates a species' relative abundance as well as its presence or absence.
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intermediate disturbance hypothesis
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regions with a moderate type, frequency, and severity of disturbance should have high species richness and diversity. intermediate levels of disturbance, communities will contain pioneering species as well as species better adapted to late-successional conditions.
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grazing food chin
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primary consumers are key link in this. the collection of organisms that eat plants, along with organisms that eat herbivores.
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what limits length of food chains
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1. there should be more trophic levels (longest food chains) in ecosystems with higher productivity.
2. long food chains are easily disrupted by droughts, floods, or other disturbances and thus tend to be eliminated. it took longer to recover. lengths of food chains should increase with stability of environment. 3. food-chain length is a function of an ecosystem's physical structure... two dimensional ecosystems should have shorter food chain, and longer one should be 3-D. |
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gross primary productivity
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total amount of photo in a given area and time period
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gross photosynthetic efficiency
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efficiency with which plants use the total amount of energy available to them.
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secondary production
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production of new tissue by primary consumers
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biogeochemical cycle
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the path that an element takes as it moves from abiotic systems through organisms and back again. to study this: 1. what are nature and size of RESERVOIRS, or areas where elements are stored for a period of time? 2. how fast does element move between reservoir, and what factors influence these rates? 3. how does biogeochemical cycle interact with other cycles?
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humus
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completely decayed organic material, it is rich in a family of carbon-containing molecules called humic acids. organic matter are converted to inorganic form by bacteria and archaea and make them available to plants
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watersheds
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a test to see the effect of vegetation removal on nutrient export. it's a large-scale experiment , where they chose two similar watersheds, areas drained by a single stream. they cut all vegetation from forests in one of two watersheds. it was treated with herbicide to prevent vegetation from regrowing. losses from devegetated site were 10 times higher than control site. nutrients wash out absence of vegetation. nutrients in soil are either dissolved in water or attached to small particles of sand or clay, and plant roots don't hold the soil particles in place.
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greenhouse gas
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carbon dioxide. it traps heat that has been radiated from earth and keeps it from being lost to space, similar to the way the glass of a greenhouse traps heat. it also absorbs and reflects the infrared wavelengths radiating from earth's surface.
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human fixed nitrogen
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1. industrially produced fertilizers, 2. cultivation of crops, such as soybeans and peas that harbor nitrogen fixing bacteria, and 3. production of nitric oxide during combustion of fossil fuels.
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measurements of biodiversity
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1. genetic diversity, total genetic info contained in all individuals of species. 2. species diversity: variety of species on earth. 3. ecosystem diversity: variety of biotic communities in a region along with abiotic components, such as soil, water and nutrients.
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endemic species
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species that are found in an area and nowhere else.
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reasons for endangerment
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habitat loss in terrestrial environments. overharvesting in marine species, pollution in freshwater. also predation/competition, natural disturbances.
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habitat fragmentation causes these...
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1. too small to support some species, 2. reduce ability of individuals to disperse from one habitat to another, and 3. fragmentation creates large amounts of "edge" habitat. (inbreeding, genetic drift)
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species-area relationships
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a way to estimate rates of extinction based on well-documented way given reasonable projections of habitat loss.
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sustainability
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managed use of resources at a rate only as fast as the rate at which they are replaced.
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species richness has positive impact on NPP...
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1. resource use efficiency: diversity in plants make more efficient use of sunlight, water, and other resources available and lead to greater overall productivity. 2. facilitation: certain species or functional groups facilitate the growth of other species by providing them with nutrients, partial shade or other benefits. 3. sampling effects: if diversity is high, extremely productive species are likely to be in there.
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resistance
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how much a community is affected by a disturbance
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resilience
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measure of how quickly a community recovers following a disturbance
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gap analysis program (GAP)
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measure of how efficiently is existing network of protected areas protecting biodiversity? it tries to identify gaps between geographic areas that are particularly rich in biodiversity and areas that are actually managed for the preservation of biodiversity. implies that earth's surface area that is now being managed for biodiversity won't be enough to conserve many species.
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