BSC 116 BSC 116
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Test 4 Study Guide Chapter 50 Sensory and Motor Mechanics Vocabulary Amplification The strengthening of stimulus energy during transduction Cardiac Muscle A type of striated muscle that forms the contractile wall of the heart. Its cells are joined by intercalated disks that relay the electrical signals underlying each heartbeat Chemoreceptor A sensory receptor that responds to a chemical stimulus, such as a solute or an odorant Chitin A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods Cochlea The complex, coiled organ of hearing that contains the organ of Corti Compound Eye A type of multifaceted eye in insects and crustaceans consisting of up to several thousand light detecting, focusing ommatidia Cone A cone shaped cell in the retina of the vertebrate eye, sensitive to color Cuticle (1) A waxy covering on the surface of stems and leaves that prevents desiccation in terrestrial plants. (2) The exoskeleton of an arthropod, consisting of layers of protein and chitin that are variously modified for different functions. (3) A tough coat that covers the body of a nematode Electromagnetic Receptor A receptor of electromagnetic energy, such as visible light, electricity, or magnetism Endoskeleton A hard skeleton buried within the soft tissues of an animal Eustachian Tube The tube that connects the middle ear to the pharynx Exoskeleton A hard encasement on the surface of an animal, such as the shell of a mollusk or the cuticle of an arthropod, that provides protection and points of attachment for muscles Fast Twitch Fiber A muscle fiber used for rapid, powerful contractions Fovea The place on the retina at the eye’s center of focus, where cones are highly concentrated Gustation The sense of taste Hair Cell A mechanosensory cell that alters output to the nervous system when hairlike projections on the cell surface are displaced Hydrostatic Skeleton A skeletal system composed of fluid held under pressure in a closed body compartment; the main skeleton of most cnidarians, flatworms, nematodes, and annelids Intercalated Disk A specialized junction between cardiac muscle cells that provides direct electrical coupling between the cells Iris The colored part of the vertebrate eye, formed by the anterior portion of the choroid Lateral Line System A mechanoreceptor system consisting of a series of pores and receptor units along the sides of the body in fishes and aquatic amphibians; detects water movements made by the animal itself and by other moving objects Lens The structure in an eye that focuses light rays onto the photoreceptors Locomotion Active motion from place to place Motor Unit A single motor neuron and all the muscle fibers it controls Myofibril A longitudinal bundle in a muscle cell (fiber) that contains thin filaments of actin and regulatory proteins and thick filaments of myosin Myoglobin An oxygen storing, pigments protein in muscle cells Nociceptor A sensory receptor that responds to noxious or painful stimuli; also called a pain receptor Odorant A molecule that can be detected by sensory receptors of the olfactory system Olfaction The sense of smell Ommatidium One of the facets of the compound eye of arthropods and some polychaete worms Opsin A membrane protein bound to a light absorbing pigment molecule Organ of Corti The actual hearing organ of the vertebrate ear, located in the floor of the cochlear duct in the inner ear; contains the receptor cells (hair cells) of the ear Oval Window In the vertebrate ear, a membrane covered gap in the skull bone, through which sound waves pass from the middle ear to the inner ear Pain Receptor A sensory receptor that responds to noxious or painful stimuli; also called a nociceptor Penis The copulatory structure of male mammals Perception The interpretation of sensory system input by the brain Peristalsis (1) Alternating waves of contraction and relaxation in the smooth muscles lining the alimentary canal that push food along the canal. (2) A type of movement on land produced by rhythmic waves of muscle contractions passing from front to back, as in many annelids Photoreceptor An electromagnetic receptor that detects the radiation known as visible light Pupil The opening in the iris, which admits light into the interior of the vertebrate eye. Muscles in he iris regulate its size Receptor Potential An initial response of a receptor cell to a stimulus, consisting of a change in voltage across the receptor membrane proportional to the stimulus strength Retina The innermost layer of the vertebrate eye, containing photoreceptor cells (rods and cones) and neurons; transmits images formed by the lens to the brain via the optic nerve Retinal The light absorbing pigment in rods and cones of the vertebrate eye Rhodopsin A visual pigment consisting of retinal and opsin. Upon absorbing light, the retinal changes shape and dissociates from the opsin Round Window In the mammalian ear, the point of contact where vibrations of the stapes create a traveling series of pressure waves in the fluid of the cochlea Saccule In the vertebrate ear, a chamber in the vestibule behind the oval window that participates in the sense of balance Sarcomere The fundamental, repeating unit of striated muscle, delimited by the Z lines Sarcoplasmic Reticulum (SR) A specialized endoplasmic reticulum that regulates the calcium concentration in the cytosol of muscle cells Semicircular Canals A threepart chamber of the inner ear that functions in maintaining equilibrium Sensory Adaptation The tendency of sensory neurons to become less sensitive when they are stimulated repeatedly Sensory Reception The detection of a stimulus by sensory cells Sensory Receptor A specialized structure or cell that responds to a stimulus from an animal’s internal or external environment Sensory Transduction The conversion of stimulus energy to a change in the membrane potential of a sensory receptor cell SingleLens Eye The camera like eye found in some jellies, polychaete worms, spiders, and many molluscs Skeletal Muscle A type of striated muscle that is generally responsible for the voluntary movements of the body SlidingFilament Model The idea that muscle contraction is based on the movement of thin (actin) filaments along thick (myosin) filaments, shortening the sarcomere, the basic unit of muscle organization Slot Twitch Fiber A muscle fiber that can sustain long contractions Smooth Muscle A type of muscle lacking the striations of skeletal and cardiac muscle because of the uniform distribution of myosin filaments in the cells; responsible for involuntary body activities Statocyst A type of mechanoreceptor that functions in equilibrium in invertebrates by use of statoliths, which stimulate hair cells in relation to gravity Statolith In invertebrates, a dense particle that settles in response to gravity and is found in sensory organs that function in equilibrium Tastant Any chemical that stimulates the sensory receptors in a taste bud Taste Bud A collection of modified epithelial cells on the tongue or in the mouth that are receptors for taste in mammals Test In foram protists, a porous shell that consists of a single piece of organic material hardened with calcium carbonate Tetanus The maximal, sustained contraction of a skeletal muscle, caused by a very high frequency of action potential elicited by continual stimulation Thermoreceptor A receptor stimulated by either heat or cold Thick Filament A filament composed of staggered arrays of myosin molecules; a component of myofibrils in muscle fibers Thin Filament A filament consisting of two strands of actin and two strands of regulatory protein coiled around one another; a component of myofibrils in muscle fibers Transmission The passage of a nerve impulse alone axons Transverse (T) Tubule An infolding of the plasma membrane of skeletal muscle cells Tropomyosin The regulatory protein that blocks the myosin binding sites on actin molecules Troponin Complex The regulatory proteins that control the position of tropomyosin on the thin filament Tympanic Membrane Another name for the eardrum, the membrane between the outer and middle ear Key Facts Sensory receptors transduce stimulus energy and transmit signals to the central nervous system The detections of a stimulus precedes sensory transduction, the change in the membrane potential of a sensory receptor in response to a stimulus. The resulting receptor potential controls transmission of action potentials to the CNS, where sensory information is integrated to generate perceptions. The frequency of action potentials in an axon and the number of axons activated determine stimulus strength. The identity of the axon carrying the signal encodes the nature or quality of the stimulus. Mechanoreceptors respond to stimuli such as pressure, touch, stretch, motion, and sound. Chemoreceptors detect either total solute concentrations or specific molecules. Electromagnetic receptors detect different forms of electromagnetic radiation. Thermoreceptors signal surface and core temperatures of the body. Pain is detected by a group of nociceptors that respond to excess heat, pressure or specific class of chemicals The mechanoreceptors responsible for hearing and equilibrium detect moving fluid or settling particles Most invertebrates sense their orientation with respect to gravity by means of statocysts. Specialized hair cells form the basis for hearing and balance in mammals and for detection of water movement in fishes and aquatic amphibians. In mammals, the tympanic membrane (eardrum) transmits sound waves to bones of the middle ear, which transmit the waves through the oval window to the fluid in the coiled cochlea of the inner ear. Pressure waves in the fluid vibrate the basilar membrane, depolarizing hair cells and triggering action potentials that travel via the auditory nerve to the brain. Receptors in the inner ear function in balance and equilibrium The diverse visual receptors of animals depend on lightabsorbing pigments Invertebrates have varied light detectors, including simple lightsensitive eyespots, imageforming compound eyes, and singlelens eyes. In the vertebrate eye, a single lens is used to focus light on photoreceptors in the retina. Both rods and cones contain a pigment, retinal, bonded to a protein (opsin). Absorption of light by retinal triggers a signal transduction pathway that hyperpolarizes the photoreceptors, causing them to release less neurotransmitter. Synapses transmit information from photoreceptors to cells that integrate information and convey it to the brain along axons that form the optic nerve The senses of taste and smell rely on similar sets of similar sets of sensory receptors Taste (gustation) and small (olfaction) depend on stimulation of chemoreceptors by small dissolved molecules. In humans, sensory cells in taste buds express a receptor type specific for one of the five taste perceptions: sweet, sour, salty, bitter and umami (elicited by glutamate). Olfactory receptor cells line the upper part of the nasal cavity. More than 1,000 genes code for membrane proteins that bind to specific classes of odorants, and each receptor cell appears to express only one of those genes The physical interaction of protein filaments is required for muscle function The muscle cells (fibers) of vertebrate skeletal muscle contain myofibrils composed of thin filaments of (mostly) actin and thick filaments of myosin. These filaments are organized into repeating units called sarcomeres. Myosin heads, energized by the hydrolysis of ATP, bind to the thin filaments, form cross bridges, and then release upon binding ATP anew. As this cycle repeats, the thick and thin filaments slide past each other, shortening the sarcomere and contracting the muscle fiber Motor neurons release acetylcholine, triggering action potentials in muscle fibers that stimulate the release of Ca2+ from the sarcoplasmic reticulum. When the Ca2+ binds the troponin complex, tropomyosin moves, exposing the myosinbinding sites on actin and thus initiating crossbridge formation. A motor unit consists of a motor neuron and the muscle fibers it controls. A twitch results from one action potential. Skeletal muscle fibers are slowtwitch or fasttwitch and oxidative or glycolytic Cardiac muscle, found in the heart, consists of striated cells electrically connected by intercalated disks and generate action potentials without input from neurons. In smooth muscles, contractions are initiated by the muscles or by stimulation from neurons in the autonomic nervous system. Skeletal systems transform muscle contraction into locomotion Skeletal muscles, often in antagonistic pairs, contract and pull against the skeleton. Skeletons may be hydrostatic and maintain by fluid pressure, as in worms; hardened into exoskeletons, as in insects; or in the form of endoskeletons, as in vertebrates Each form of locomotion – swimming, movement on land, or flying – presents a particular challenge. For example, swimmers need to overcome friction, but face less of a challenge from gravity than do animals that move on land or fly Chapter 51 Animal Behavior Vocabulary Altruism Selflessness; behavior that reduces an individual’s fitness while increasing the fitness or another individual Associative Learning The acquired ability to associate one environmental feature (such as color) with another (such as danger) Behavior Individually, an action carried out by muscles or glands under control of the nervous system in response to a stimulus; collectively, the sum of an animal’s responses to external and internal stimuli Behavioral Ecology The study of the evolution of and ecological basis for animal behavior Coefficient of Relatedness The fraction of genes that, on average, are shared by two individuals Cognition The process of knowing that may include awareness, reasoning, recollection and judgment Cognitive Map A neural representation of the abstract spatial relationships between objects in an animal’s surroundings Cross Fostering Study A behavioral study in which the young of one species are placed in the care of adults from another species Culture A system of information transfer through social learning or teaching that influences the behavior of individuals in a population Fixed Action Pattern In animal behavior, a sequence of unlearned acts that is essentially unchangeable and, once initiated, usually carried to completion Foraging The seeking and obtaining of food Game Theory An approach to evaluating alternative strategies in situations where the outcome of a particular strategy depends on the strategies used by other individuals Hamilton’s Rule The principle that for natural selection to favor an altruistic act, the benefit to the recipient, devalued by the coefficient of relatedness, must exceed the cost to the altruist Imprinting In animal behavior, the formation at a specific stage in life of a longlasting behavioral response to a specific individual or object Inclusive Fitness The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives to increase production of their offspring Innate Behavior Animal behavior that is developmentally fixed and under strong genetic control. Innate behavior is exhibited in virtually the same form by all individuals in a population despite internal and external environmental differences during development and throughout their lifetimes Kin Selection Natural selection that favors altruistic behavior by enhancing the reproductive success of relatives Learning The modification of behavior as a result of specific experiences Mate Choice Copying Behavior in which individuals in a population copy the mate choice of others, apparently as a result of social learning Migration A regular, long distance change in location Monogamous Referring to a type of relationship in which one male mates with just one females Optimal Foraging Model The basis for analyzing behavior as a compromise between feeding costs and feeding benefits Pheromone In animals and fungi, a small molecule released into the environment that functions in communication between members of the same species. In animals, it acts much like a hormone in influencing physiology and behavior Polygamous Referring to a type of relationship in which an individual of one sex mates with several of the other Problem Solving The cognitive activity of devising a method to proceed from one state to another in the face of real or apparent obstacles Reciprocal Altruism Altruistic behavior between unrelated individuals, whereby the altruistic individual benefits in the future when the beneficiary reciprocates Sign Stimulus An external sensory cue that triggers a fixed action pattern by an animal Signal In animal behavior, transmission of a stimulus from one animal to another. The term is also used in the context of communication in other kinds of organisms and in celltocell communication in all multicellular organisms Slow Block to Polyspermy The formation of the fertilization envelope and other changes in an egg’s surface that prevent fusion of the egg with more than one sperm. The slow block begins about 1 minute after fertilization Social Learning Modification of behavior through the observation of other individuals Sociobiology The study of social behavior based on evolutionary theory Spatial Learning The establishment of a memory that reflects the environment’s spatial structure Twin Study A behavioral study in which researchers compare the behavior of identical twins raised apart with that of identical twins raised in the same households Key Facts Discrete sensory inputs can stimulate both simple and complex behaviors Behavior is the sum of an animal’s responses to external and internal stimuli. In behavior studies, proximate, or “how”, questions focus on the stimuli that trigger a behavior and on genetic, physiological, and anatomical mechanisms underlying a behavioral act. Ultimate, or “why”, questions address evolutionary significance. A fixed action pattern is a largely invariant behavior triggered by a simple cue known as a sign stimulus. Migratory movements involve navigation, which can be based on orientation relative to the sun, the stars, or Earth’s magnetic field. Animal behavior is often synchronized to the circadian cycle of light and dark in the environment or to cues that cycle over the seasons. The transmission and reception of signals constitute animal communication. Animals use visual, auditory, chemical and tactile signals. Chemical substances called pheromones transmit speciesspecific information between members of a species in behaviors ranging from foraging to courtship. Learning establishes specific links between experience and behavior Crossfostering studies can be used to measure the influence of social environment and experience on behavior Learning, the modification of behavior as a result of experience can take many forms: imprinting, cognition, associative learning, social learning and spatial learning Selection for individual survival and reproductive success can explain diverse behaviors Controlled experiments in the laboratory can give rise to interpretable evolutionary changes in behavior An optimal foraging model is based on the idea that natural selection should favor foraging behavior that minimizes the costs of foraging and maximizes the benefits Sexual dimorphism correlates with the type of mating relationship between males and females. These include monogamous and polygamous mating systems. Variations in mating system and mode of fertilization affect certainty of paternity, which in turn has a significant influence on mating behavior and parental care Game theory provides a way of thinking about evolution in situations where the fitness of a particular behavioral phenotype is influenced by other behavioral phenotypes in the population Genetic analyses and the concept of inclusive fitness provide a basis for studying the evolution of behavior Genetic studies in insects have revealed the existence of master regulatory genes that control behaviors. Within the underlying hierarchy, multiple genes influence specific behaviors, such s a courtship song. Research on voles has revealed that variation in a single gene can determine differences in complex behaviors involved in both mating and parenting When behavioral variation within a species correlates with variation in environmental conditions, it may be evidence of past evolution. Field and laboratory studies have documented the genetic basis for a change in migratory behavior of certain birds and revealed behavioral differences in snakes that correlate with geographic variation in prey availability. Altruism can be explained by the concept of inclusive fitness, the total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables close relatives to produce offspring. The coefficient of relatedness and Hamilton’s rule provide a way of measuring the strength of the selective forces favoring altruism against the potential cost of the “selfless” behavior. Kin selection favors altruistic behavior by enhancing the reproductive success of relatives. Chapter 52 An Introduction to Ecology and the Biosphere Vocabulary Abiotic Nonliving; referring to the physical and chemical properties of an environment Abyssal Zone The part of the ocean’s benthic zone between 2,000 and 6,000 m deep Aphotic Zone The part of an ocean or lake beneath the photic zone, where light does not penetrate sufficiently for photosynthesis to occur Benthic Zone The bottom surface of an aquatic environment Benthos The communities of organisms living in the benthic zone of an aquatic biome Biome Any of the world’s major ecosystem types, often classified according to the predominant vegetation for terrestrial biomes and the physical environment for aquatic biomes and characterized by adaptations of organisms to that particular environment Biosphere The entire portion of Earth inhabited by life; the sum of all the planet’s ecosystems Biotic Pertaining to the living factors – the organisms – in an environment Canopy The uppermost layer of vegetation in a terrestrial biome Chaparral A scrubland biome of dense, spiny evergreen shrubs found at midlatitudes along coasts where cold ocean currents circulate offshore; characterized by mild, rainy winters and long, hot, dry summers Climate The longterm prevailing weather conditions at a given place Climograph A plot of the temperature and precipitation in a particular region Community Ecology The study of how interactions between species affect community structure and organization Coral Reef Typically a warmwater, tropical ecosystem dominated by the hard skeletal structures secreted primarily by corals. Some coral reefs also exist in cold, deep water Deep Sea Hydrothermal Vent A dark, hot, oxygendeficient environment associated with volcanic activity on or near the seafloor. The produces in a vent community are chemoautotrophic prokaryotes Depolarization A change in a cell’s membrane potential such that the inside of the membrane is made less negative relative to the outside. For example, a neuron membrane is depolarized if a stimulus decreases its voltage from the resting potential of 70 mV in the direction of zero voltage Desert A terrestrial biome characterized by very low precipitation Detritus Dead organic matter Dispersal The movement of individuals or gametes away from their parent location. This movement sometimes expands the geographic range of a population or species Disturbance A natural or human caused event that changes a biological community and usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal role in structuring many communities. Ecology The study of how organisms interact with each other and their environment Ecosystem All the organisms in a given area as well as the abiotic factors with which they interact; one or more communities and the physical environment around them Ecosystem Ecology The study of energy flow and the cycling of chemicals among the various biotic and abiotic components in an ecosystem Ecotone The transition from one type of habitat or ecosystem to another, such as the transition from a forest to a grassland Estuary The area where a freshwater stream or river merges with the ocean Eutrophic Lake A lake that has a high rate of biological productivity supported by a high rate of nutrient cycling Global Ecology The study of the functioning and distribution of organisms across the biosphere and how the regional exchange of energy and materials affects them Intertidal Zone The shallow zone of the ocean adjacent to land and between the high and low tide lines Landscape An area containing several different ecosystems linked by exchanges of energy, materials and organisms Landscape Ecology The study of how the spatial arrangement of habitat types affects the distribution and abundance of organisms and ecosystem processes Limnetic Zone In a lake, the welllit, open surface waters far from shore Littoral Zone In a lake, the shallow, welllit waters close to shore Macroclimate Largescale patterns in climate; the climate of an entire region Marine Benthic Zone The ocean floor Microclimate Climate patterns on a very fine scale, such as the specific climatic conditions underneath a log Neritic Zone The shallow region of the ocean overlying the continental shelf Northern Coniferous Forest A terrestrial biome characterized by long, cold winters and dominated by conebearing trees Oceanic Pelagic Zone Most of the ocean’s waters far from shore, constantly mixed by ocean currents Oligotrophic Lake A nutrientpoor, clear lake with few phytoplankton Organismal Ecology The branch of ecology concerned with the morphological, physiological and behavioral ways in which individual organisms meet the challenges posed by their biotic and abiotic environments Pelagic Zone The openwater component of aquatic biomes Photic Zone The narrow top layer of an ocean or lake, where light penetrates sufficiently for photosynthesis to occur Population A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring Population Ecology The study of populations in relation to their environment, including environmental influences on population density and distribution, age structure and variations in population size Savanna A tropical grassland biome with scattered individual trees and large herbivores and maintained by occasional fires and droughts Temperate Broadleaf Forest A biome located throughout midlatitude regions where there is sufficient moisture to support the growth or large, broadleaf deciduous trees Temperate Grassland A terrestrial biome that exists at midlatitude regions and is dominated by grasses and forbs Thermocline A narrow stratum of abrupt temperature changes in the ocean and in many temperatezone lakes Tropical Dry Forest A terrestrial biome characterized by relatively high temperatures and precipitation overall but with a pronounced dry season Tropical Rain Forest A terrestrial biome characterized by relatively high precipitation and temperatures year round Tropics Latitudes between 23.5 north and south Tundra A terrestrial biome at the extreme limits of plant growth. At the northernmost limits, it is called the arctic tundra, and at high altitudes, where plant forms are limited to low shrubby or matlike vegetation, it called alpine tundra Turnover The mixing of waters as a result of changing water temperature profiles in a lake Wetland A habitat that in inundated by water at least some of the time and that supports plants adapted to water saturated soil Key Facts Earth’s climate varies by latitude and season and is changing rapidly Global climate patterns are largely determined by the input of solar energy and Earth’s revolution around the sun The changing angle of the sun over the year, bodies or water, and mountains exert seasonal, regional and local effects on macroclimate Fine scale differences in abiotic (nonliving) factors, such as sunlight and temperature, determine microclimate Increasing greenhouse gas concentrations in the air are warming Earth and altering the distributions of many species. Some species will not be able to shift their ranges quickly enough to reach suitable habitat in the future The structure and distribution of terrestrial biomes are controlled by climate and disturbance Climographs show that temperature and precipitation are correlated with biomes. Because other factors also play roles in biomes location, biomes overlap Terrestrial biomes are often named for major physical or climatic factors and for their predominant vegetation. Vertical layering is an important feature of terrestrial biomes. Disturbance, both natural and human induced, influences the type of vegetation found in biomes. Humans have altered much of Earth’s surface, replacing the natural terrestrial communities with urban and agricultural ones The pattern of climatic variation is as important as the average climate in determining where biomes occur Aquatic biomes are diverse and dynamic systems that cover most of Earth Aquatic biomes are characterized primarily by their physical environment rather than by climate and are often layered with regard to light penetration, temperature and community structure. Marine biomes have a higher salt concentration than freshwater biomes In the ocean and in most lakes, an abrupt temperature change called a thermocline separates a more uniformly warm upper layer form more uniformly cold deeper waters Many temperate lakes undergo a turnover or mixing of water in spring and fall that sends deep, nutrient rich water to the surface and shallow, oxygen rich water to deeper layers Chapter 53 Population Ecology Vocabulary Age Structure The relative number of individuals of each age in a population Carrying Capacity The maximum population size that can be supported by the available resources, symbolized as K Cohort A group of individuals of the same age in a population Demographic Transition In a stable population, a shift from high birth and death rates to low birth and death rates Demography The study of changes over time in the vital statistics of populations, especially birth rates and death rates Density The number of individuals per unit area or volume Density Independent Referring to any characteristic that is not affected by population density Dispersion The pattern of spacing among individuals within the boundaries of a population Ecological Footprint The aggregate land and water area required by a person, city, or nation to produce all of the resources it consumes and to absorb all of the wastes it generates Ecological Niche (Nich) The sum of a species’ use of the biotic and abiotic resources in its environment Emigration The movement of individuals out of a population Exponential Population Growth Growth of a population in an ideal, unlimited environment, represented by a Jshaped curve when population size is plotted over time Immigration The influx of new individuals into a population from other areas Iteroparity Reproduction in which adults produce offspring over many years; also called repeated reproduction K Selection Selection for life history traits that are sensitive to population density; also called densitydependent selection Life History The traits that affect an organism’s schedule of reproduction and survival Life Table An age specific summary of the survival pattern of a population Logistic Population Growth Population growth that levels off as population size approaches carrying capacity Mark Recapture Method A sampling technique used to estimate the size of animal populations Metapopulation A group of spatially separated populations of one species that interact through immigration and emigration Population A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring Population Dynamics The study of how complex interactions between biotic and abiotic factors influence variations in population size Reproductive Table An age specific summary of the reproductive rates in a population R Selection Selection for life history traits that maximize reproductive success in uncrowded environments; also called densityindependent selection Semelparity Reproduction in which an organism produces all of its offspring in a single event; also called big band reproduction Survivorship Curve A plot of the number of members of a cohort that are still alive at each age; one way to represent age specific mortality Sympathetic Division One of three divisions of the autonomic nervous system; generally, increases energy expenditure and prepares the body for action Territoriality A behavior in which an animal defends a bounded physical space against encroachment by other individuals, usually of its own species Zero Population Growth (ZPG) A period of stability in population size, when additions to the population through births and immigration are balanced by subtractions through deaths and emigration Key Facts Biological processes influence population density, dispersion and demographics Population density – the number of individuals per unit area or volume – reflects the interplay of births, deaths, immigration, and emigration. Environmental and social factors influence the dispersion of individuals Populations increase from births and immigration and decrease from deaths and emigration. Life tables, survivorship curves, and reproductive tables summarize specific trends in demography The exponential model describes population growth in an idealized, unlimited environment If immigration and emigration are ignored, a population’s growth rate (the per capita rate of increase) equals its birth rate minus its death rate The exponential growth equation dN/dt = rN represents a population’s growth when resources are relatively abundant, where r is the instantaneous per capita rate of increase and N is the number of individuals in the population The logistic model describes how a population grows more slowly as it nears its carrying capacity Exponential growth cannot be sustained for long in any population. A more realistic population model limits growth by incorporating carrying capacity (K), the maximum population size the environment can support According to the logistic growth equation dN/dt = rN (KN)/K, growth levels off as population size approaches the carrying capacity The logistic model fits few populations perfectly, but it is useful for estimating possible growth Life history traits are products of natural selection Life history traits are evolutionary outcomes reflected in the development, physiology and behavior of organisms Big bang, or semelparous organisms reproduce once and die. Iteroparous organisms produce offspring repeatedly Life history traits such as brood size, age at maturity, and parental caregiving represents tradeoffs between conflicting demands for time, energy, and nutrients. Two hypothetical life history patterns are K selection, or densitydependent selection, and r selection, or densityindependent selection Many factors that regulate population growth are density dependent In density dependent population regulation, death rates rise and birth rates fall with increasing density. In density independent population regulation, birth and death rates do not vary with density Density dependent changes in birth and death rates curb population increase through negative feedback and can eventually stabilize a population near its carrying capacity. Density dependent limiting factors include intraspecific competition for limited food or space, increased predation, disease, intrinsic physiological factors and buildup of toxic substances Because changing environmental conditions periodically disrupt them, all populations exhibit some size fluctuations. Many populations undergo regular boomandbust cycles that are influenced by complex interactions between biotic and abiotic factors. A metapopulation is a group of populations linked by immigration and emigration The human population is no longer growing exponentially but is still increasing rapidly Since about 1650, the global human population has grown exponentially, but within the last 50 years, the rate of growth has fallen by half. Differences in age structure show that while some nations’ populations are growing rapidly, those of others are stable or declining in size. Infant mortality rates and life expectancy at birth vary widely in different countries. Ecological footprint is the aggregate land and water area needed to produce all the resources a person or group of people consume and to absorb all of their wastes. It is one measure of how close we are to the carrying capacity of Earth, which is uncertain. With a world population of more than 7 billion people, we are already using many resources in an unsustainable manner Chapter 54 Community Ecology Vocabulary Aposematic Coloration The bright warning coloration of many animals with effective physical or chemical defenses Batesian Mimicry A type of mimicry in which a harmless species looks like a species that is poisonous or otherwise harmful to predators Biomanipulation An approach that applies the topdown model of community organization to alter ecosystem characteristics. For example, ecologists can prevent algal blooms and eutrophication by altering the density of higherlevel consumers in lakes instead of by using chemical treatments. Biomass The total mass of organic matter comprising a group of organisms in a particular habitat Bottom Up Model A model of community organization in which mineral nutrients influence community organization by controlling plant of phytoplankton numbers, which in turn control herbivore numbers, which in turn control predator numbers Character Displacement The tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations of the same two species Commensalism A symbiotic relationship in which one organism benefits but the other is neither helped nor harmed Competitive Exclusion The concept that when populations of two similar species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population. Cryptic Coloration Camouflage that makes a potential prey difficult to spot against its background Disturbance A natural or human caused event that changes a biological community and usually removes organisms from it. Disturbances, such as fires and storms, play a pivotal role in structuring many communities Dominant Species A species with substantially higher abundance or biomass than other species in a community. Dominant species exert a powerful control over the occurrence and distribution of other species Ecological Succession Transition in the species composition of a community following a disturbance; establishment of a community in an area virtually barren of life Ecosystem Engineer An organism that influences community structure by causing physical changes in the environment Ectoparasite A parasite that feeds on the external surface of a host Endoparasite A parasite that lives within a host Energetic Hypothesis The concept that the length of a food chain is limited by the inefficiency of energy transfer along the chain Evapotranspiration The total evaporation of water from an ecosystem, including water transpired by plants and evaporated from a landscape, usually measured in millimeters and estimated for a year Facilitation An interaction in which one species has a positive effect on the survival and reproduction of another species without the intimate association of a symbiosis Food Chain The pathway along which food energy is transferred form trophic level to trophic level, beginning with producers Food Web The interconnected feeding relationships in an ecosystem Herbivory An interaction in which an organism eats part of a plant of alga Intermediate Disturbance Hypothesis The concept that moderate levels of disturbance can foster greater species diversity than low or high levels of disturbance Interspecific Competition Competition for resources between individuals of two or more species when resources are in short supply Interspecific Interaction A relationship between individuals of two or more species in a community Invasive Species A species, often introduced by humans, that takes hold outside its native range Keystone Species A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role or niche Mullerian Mimicry Reciprocal mimicry by two unpalatable species Mutualism A symbiotic relationship in which both participants benefit Nonequilibrium Model A model that maintains that communities change constantly after being buffeted by disturbances Parasite An organism that feeds on the cell contents, tissues, or body fluids of another species (the host) while in or on the host organism. Parasites harm but usually do not kill their host Predation An interaction between species in which one species, the predator, eats the other, the prey Primary Succession A type of ecological succession that occurs in an area where there were originally no organisms present and where soil has not yet formed Production Efficiency The percentage of energy stored in assimilated food that is not used for respiration or eliminated as waste Relative Abundance The proportional abundance of different species in a community Resource Partitioning The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species Secondary Succession A type of succession that occurs where an existing community has been cleared by some disturbance that leaves the soil or substrate intact Shannon Diversity An index of community diversity symbolized by H and represented by the equation H = −(p An p A+ p Bln p B p Cln p C+ . . .), where A, B, C . . . are species, p is the relative abundance of each species, and ln is the natural logarithm. Species Diversity The number and relative abundance of species in a biological community Species Richness The number of species in a biological community Species Area Curve The biodiversity pattern that shows that the larger the geographic area of a community is, the more species it has Symbiosis An ecological relationship between organisms of two different species that live together in direct and intimate contact Top Down Model A model of community organization in which predation influences community organization by controlling herbivore numbers, which in turn control plant of phytoplankton numbers, which in turn control nutrient levels; also called the trophic cascade model Trophic Structure The different feeding relationships in an ecosystem, which determine the route of energy flow and the pattern of chemical cycling Vector An organism that transmits pathogens from one host to another Key Facts Community interactions are classified by whether they help, harm or have no effect on the species involved A variety of interspecific interactions affect the survival and reproduction or the species that engage in them. These interactions include interspecific competition, predation, herbivory, symbiosis and facilitation Competitive exclusion states that two species competing for the same resource cannot coexist permanently in the same place. Resource partitioning is the differentiation of ecological niches that enables species to coexist in a community Interspecific Interaction Description Interspecific competition (/) Two or more species compete for a resource that is in short supply Predation (+/) One species, the predator, kills and eats the other, the pray. Predation has led to diverse adaptations, including mimicry Herbivory (+/) An herbivore eats part of a plant of alga Symbiosis Individuals of two or more species live in close contact with one another. Symbiosis includes parasitism, mutualism and commensalism Parasitism (+/) The parasite derives its nourishment from a second organism, its host, which is harmed Mutualism (+/+) Both species benefit from the interaction Commensalism (+/0) One species benefits from the interaction, while the other is unaffected by it Facilitation (+/+ or 0/+) Species have positive effects on the survival and reproduction of other species without the intimate contact of a symbiosis Diversity and trophic structure characterize biological communities Species diversity measures the number of species in a community – its species richness – and their relative abundance More diverse communities typically produce more biomass and show less yeartoyear variation in growth than less diverse communities and are more resistant to invasion by exotic species Trophic structure is a key factor in community dynamics. Food chains link the trophic levels from producers to top carnivores. Branching food chains and complex trophic interactions from food webs Dominant species are the most abundant species in a community. Keystone species are usually less abundant species that exert a disproportionate influence on community structure The bottom up model proposes a unidirectional influence from lower to higher trophic levels, in which nutrients and other abiotic factors primarily determine community structure. The top down model proposes that control of each trophic level comes from the trophic level above, with the result that predators control herbivores, which in turn control primary producers Disturbance influences species diversity and composition Increasing evidence suggest that disturbance and lack of equilibrium, rather than stability and equilibrium, are the norm for most communities. According to the intermediate disturbance hypothesis, moderate levels of disturbance can foster higher species diversity than can low or high levels of disturbance Ecological succession is the sequence of community and ecosystem changes after a disturbance. Primary succession occurs where no soil exists when succession begins; secondary succession begins in an area where soil remains after a disturbance Biogeographic factors affect community diversity Species richness generally declines along a latitudinal gradient from the trophics to the poles. The greater are of tropical environments may account for their greater species richness Species richness is directly related to a community’s geographic size, a principle formalized in the speciesarea curve Species richness on islands depends on island size and distance from the mainland. The island equilibrium model maintains that species richness on an ecological island reaches an equilibrium where new immigrants are balanced by extinctions Pathogens alter community structure locally and globally Recent work has highlighted the role that pathogens play in structuring terrestrial and marine communities Zoonotic pathogens are transferred from other animals to humans and cause the largest class of emerging human diseases. Community ecology provides the framework for identifying key species interactions associated with such pathogens and for helping us track and control their spread Chapter 55 Ecosystems and Restoration Ecology Vocabulary Biogeochemical Cycle Any of the various chemical cycles, which involve both biotic and abiotic components of ecosystems Biological Augmentation An approach to restoration ecology that uses organisms to ass essential materials to a degraded ecosystem Bioremediation The use of organisms to detoxify and restore polluted and degraded ecosystems Decomposer An organism that absorbs nutrients from nonliving organic material such as corpses, fallen plant material, and the wastes of living organisms and converted them to inorganic forms; a detritivore Detritivore A consumer that derives its energy and nutrients from nonliving organic material such as corpses, fallen plant material and the wastes of living organisms; a decomposer Detritus Dead organic matter Ecosystem All the organisms in a given area as well as the abiotic factors with which they interact; one or more communities and the physical environment around them Eutrophication A process by which nutrients, particularly phosphorus and nitrogen, become highly concentrated in a body of water, leading to increased growth of organisms such as algae or cyanobacteria Gross Primary Production (GPP) The total primary production of an ecosystem Law of Conservation of Mass A physical law stating that matter can change form but cannot be created or destroyed. In a closed system, the mass of the system is constant Limiting Nutrient An element that must be added for production to increase in a particular area Net Ecosystem Production (NEP) The gross primary production of an ecosystem minus the energy used by all autotrophs and heterotrophs for respiration Primary Consumer An herbivore; an organism that eats plants or other autotrophs Primary Producer An autotroph, usually a photosynthetic organism. Collectively, autotrophs make up the trophic level of an ecosystem that ultimately supports all other levels Primary Production The amount of light energy converted to chemical energy (organic compounds) by the autotrophs in an ecosystem during a given time period Producer An organism that produces organic compounds from CO2 by harnessing light energy (in photosynthesis) or by oxidizing inorganic chemicals (in chemosynthetic reactions carried out by some prokaryotes) Secondary Consumer A carnivore that eats herbivores Secondary Production The amount of chemical energy in consumer’s food that is converted to their own new biomass during a given time period Tertiary Consumer A carnivore that eats other carnivores Trophic Efficiency The percentage of production transferred from one trophic level to the next higher trophic level Turnover Time The time required to replace the standing crop of a population or group of populations calculated as the ratio of standing crop to production Zoonotic Pathogen A diseasecausing agent that is transmitted to humans from other animals Key Facts Physical laws govern energy flow and chemical cycling in ecosystems An ecosystem consists of all the organisms in a community and all the abiotic factors with which they interact. The laws of physics and chemistry apply to ecosystems, particularly regarding the conservation of energy. Energy is conserved but degraded to heat during ecosystem processes. Chemical elements enter and leave an ecosystem and cycle within it, subject to the law of conservation of mass. Inputs and outputs are generally small compared to recycled amounts, but their balance determines whether the ecosystem gains or loses and element over time. Energy and other limiting factors control primary production in ecosystems Primary production sets the spending limit for the global energy budget. Gross primary production is the total energy assimilated by an ecosystem in a given period. Net primary production, the energy accumulated in autotroph biomass, equals gross primary production minus the energy used by the primary producers for respiration. Net ecosystem production is the total biomass accumulation of an ecosystem, defined as the difference between gross primary production and total ecosystem respiration In aquatic ecosystems, light and nutrients limit primary production. In terrestrial ecosystems, climatic factors such a temperature and moisture affect primary production at large scales, but a soil nutrient if often the limiting factor locally. Energy transfer between trophic levels is typically only 10% efficient The amount of energy available to each trophic level is determined by the net primary production and the production efficiency, the efficiency with which food energy is converted to biomass at each link in the food chain The percentage of energy transferred from one trophic level to the next, called trophic efficiency, is typically 10%. Pyramids of net production and biomass reflect low trophic efficiency Biological and geochemical processes cycle nutrients and water in ecosystems Water moves in a global cycle driven by solar energy. The carbon cycle primarily reflects the reciprocal processes of photosynthesis and cellular respiration. Nitrogen enters ecosystems through atmospheric deposition and nitrogen fixation by prokaryotes The proportion of a nutrient in a particular form and its cycling in that form vary among ecosystems, largely because of the differences in the rate of decomposition Nutrient cycling is strongly regulated by vegetation. The Hubbard Brook case study showed that logging increases water runoff and can cause large losses of minerals Restoration ecologists return degraded ecosystems to a more natural state Restoration ecologists harness organisms to detoxify polluted ecosystems through
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