Ecology and the Biosphere

Ecology and the BiosphereCh. 50 (Introduction to Ecology and the Biosphere)I. Ecology is the scientific study of the interactions between organisms and the environment.Events that occur in the framework of ecological season gene ramble into effects over the longer scale of evolutionary metre.The environment of any organism includes two components.Abiotic, or nonliving, components chemical and physical factors such as temperature, light, water, and foods.Biotic, or living, components solely the organisms, or the biota, that argon part of the single(a)s environment.Ecology apprise be divided into atomic estimate 18as of study ranging from the ecology of individual organisms to the dynamics of eco transcriptions and landscapes.Organismal ecology croup be subdivided into the disciplines of physiological ecology, evolutionary ecology, and conductal ecology.Concerns how an organisms structure, physiology, and demeanour meet the challenges posed by the environmentPopulation ecol ogyConcent rank mainly on factors that affect how some(prenominal) individuals of a particular species live in an bea.Population group of individuals of the alike species living in a particular geographic bea.Community ecologyDeals with the upstanding array of interacting species in a community.Community all the organisms of all the species that inhabit a particular areaEcosystem ecologyThe emphasis in this ecology is on energy flow and chemical cycling among the various biotic and abiotic components.Ecosystem all the abiotic factors in addition to the entire community of species that exist in a legitimate area.Landscape ecologyDeals with arrays of ecosystems and how they are arranged in a geographic region.Patchiness is an environmental characteristic where a landscape or seascape consists of a Mosaic of different types of patches.Focuses on the factors controlling exchanges of energy, materials, and organisms among the ecosystem patches.The biosphere is the global ecosy stem, the sum of all the planets ecosystems.II. Interactions between organisms and the environment limit the dispersal of speciesBiogeography is the study of the past and present distribution of individual species, in the context of evolutionary theoryIt provides a good starting point for understanding what limits the geographic distribution of a species.Factors limiting a species distribution may includeDispersal.Behavior.Biotic factors.Abiotic factors.Dispersal is the movement of individuals away from centers of high existence density or from their area of originOne way to contain if dispersal is a key factor limiting distribution is to observe the results of transplants of a speciesFor a transplant to be considered successful, organisms must survive and re affirm in the new areaIf it is successful, the potential range of the species is larger than its actual range.Behavior and habitat selection may limit distribution.Plants may select their habitats by producing seeds that sho ot only under a restricted set of environmental conditionsFemale mosquitoes select specific habitats for oviposition, or the depositing of eggsBiotic factors that limit the distribution of a species may includePredationDiseaseParasitismCompetitionAbiotic factors may also limit distribution.Environmental temperature is an principal(prenominal) factor in the distribution of organisms because of its effect on biologic processesCells may rupture if the water they contain freezesProteins of most organisms denature at temperatures above 45 degrees C.Water availability is early(a) important factor.fresh water and devil dog organisms live submerged in aquatic environments.Terrestrial organisms face a nearly constant threat of desiccationSunlight provides the energy that drives all ecosystems, although only plants and other photosynthetic organisms use this energy generator directlyWind amplifies the effects of environmental temperature on organisms by increase heat firing due to evap oration and convectionIt also contributes to water loss in organisms by increasing the rate of evaporative cooling and transpirationThe physical structure, pH, and mineral composition of rocks and domain limit the distribution of plantsTemperature, water, insolateniness, and wind are the major components of climateGlobal climate conventionalismsEarths curved shape causes latitudinal variation in the intensity of sunlightSunlight strikes the tropics most directly, and the most heat and light are delivered thereEarths tilt causes seasonal variation in the intensity of solar radiation.June solstice Yankee Hemisphere tilts toward sun summertime beginsMarch equinox equator faces sun directly 12 hours of daylight and darknessDecember solstice Northern Hemisphere tilts away from sun winter beginsSeptember equinox equator faces sun directlyIntense solar radiation near the equator initiates a global pattern of air circulation and precipitation advertise flowing close to Earths surfa ce creates predictable global wind patternsMacroclimate are patterns on the global, regional, and local levelOcean streams warp climate along the coasts of continents by heating or cooling overlying air masses, which may then pass across the land.Mountains have a significant effect on the numerate of sunlight r individuallying an area, as well as on local temperature and rainwater.In addition to the global changes in day length, solar radiation, and temperature, the changing bung of the sun affects local environmentsDuring the summer and winter, many lakes in temperate regions are thermally stratified, or layered vertically according to temperatureLakes undergo a periodic mixing of their waters as a result of changing temperature profiles, a process called turnover.Microclimate are very fine patterns, such as those encountered by a community underneath a logMany features in the environment influence microcli equal by casting shade, affecting evaporation from speck, and changin g wind patterns.III. Abiotic and biotic factors influence the structure and dynamics of aquatic biomesBiomes are major types of ecological associations that occupy broad geographic regions of land or waterAquatic biomes describe of the largest part of the biosphere.These biomes are physically and chemically stratifiedThere is sufficient light for photosynthesis in the upper photic zoneLittle light penetrates in the lower aphotic zoneAt the bottom, the subtrate is called the benthic zoneIt is made up of sand and organic and inorganic sedimentsIt is occupied by communities of organisms collectively called benthonic zoneA major source of food for the benthos is dead organic matter called detritusThermal energy from sunlight sensitives surface waters to some(prenominal) depth the sunlight penetrates.In the ocean and in most lakes, a narrow stratum of rapid temperature change called a thermocline separates the more uniformly warm upper layer from more uniformly cold deeper watersMajo r aquatic biomesLakes are standing bodies of water covering thousands of square kilometersOligotrophic lakes are nutrient poor and world(a)ly oxygen richEutrophic lakes are nutrient rich and often depleted of oxygen if ice-covered in winter and in the deepest zone during summerThe littoral zone is the shallow, well-lighted waters close to shoreThe limnetic zone is further away from shore and is too deep to support rooted aquatic plantsA wetland is an area covered with water for a long enough period to support aquatic plantsThe most prominent physical characteristic of streams and rivers is currentHeadwater streams are generally cold, clear, turbulent, and swiftRivers are generally warmer and more turbid, since they carry more sediment than their headwaters.An estuary is a transition area between river and seaThey have very complex flow patternsAn intertidal zone is periodically submerged and exposed by the tides, twice daily on most marine shoresThe oceanic pelagic biome is a vast realm of open blue water, constantly mixed by wind-driven oceanic currentsReef building corals are modified to the photic zone of relatively stable tropical marine environments with high water clarityA coral reef, which is formed largely from the calcium carbonate skeletons of corals, develops over a long time on oceanic islandsThe marine benthic zone consists of the seafloor below the surface waters of the constituteal, or neritic, zone and the offshore, pelagic zone.Organisms in the very deep benthic or abyssal, zone are adapted to continuous cold and extremely high water pressureIV. mood largely determines the distribution and structure of terrestrial biomesA climograph is a plot of the temperature and precipitation in a particular regionVertical stratification is an important feature of terrestrial biomesIn many forests, the layers consist of the upper canopy, the low-tree stratum, the shrub understory, the ground layer of herbaceous plants, the forest floor, and the root lay erTerrestrial biomes normally grade into each other, without sharp boundariesThe area of intergradation is called an ecotone and may be wide or narrowMajor terrestrial biomesIn tropical rain forests, rainfall is relatively constant, and in tropical dry forests, precipitation is highly seasonalTropical forests are stratifiedDeserts occur in a tintinnabulation near 30 degrees north and south latitude or at other latitudes in the interior of continentsPrecipitation is low and highly variantTemperature is variable seasonally and dailyThe savanna is warm year-round, but with somewhat more seasonal variation than in tropical forestsChaparral occurs in midlatitude coastal regions on several continentsIt is dominated by shrubs and small trees, along with a high diversity of grasses and herbsTemperate grasslands cover parts of South Africa, Hungary, Argentina, Uruguay, Russia, and North America.The dominant plants are grasses and forbsThe northern coniferous forest, or taiga, is the larges t terrestrial biome on earthPrecipitation ranges from 30 to 70 cm, and periodic droughts are commonCone-bearing trees dominate these forestsA rise temperate broadleaf forest has distinct, highly diverse, vertical layers.Tundra covers expansive areas of the Arctic, amounting to 20% of Earths land surfaceA permanently frozen layer of soil called permafrost generally prevents water infiltration.Ch. 51 (Behavioral Ecology)I. Behavioral ecology extends observations of animal behavior by studying how such behavior is controlled and how it develops, takes, and contributes to survival and reproductive success.II. Behavioral ecologists pock between proximate and ultimate causes of behavior.Behavior traits are also a part of an animals phenotypeIt includes muscular as well as nonmuscular activityIs everything that an animal does and how it does it. nurture is also considered a behavioral process.Proximate questions focus on the environmental stimuli that trigger a behavior, as well as the familial, physiological, and anatomical mechanisms underlying a behavioral actThese are how questionsUltimate questions address the evolutionary significance of a behaviorThese are why questionsEthology is the scientific study of animal behavior, peculiarly in natural environments.Tindenbergen suggested four questions that must be answered to fully understand any behaviorWhat is the mechanistic basis of the behavior, including chemical, anatomical, and physiological mechanisms?How does development of the animal, from zygote to mature individual, influence behavior?What is the evolutionary history of the behavior?How does the behavior contribute to survival and reproduction?The fixed action pattern is a sequence of unknowing behavioral acts that Is essentially unchangeable and is carried to completionA FAP is triggered by an external sensory stimulus known as a sign stimulusimprint is a type of behavior that includes some(prenominal) learning and innate components and is generally irreversibleA sensitive period is a limited phase in an animals development that is the only time when certain behaviors can be learnedIII. Many behaviors have a strong genetic component.Biologists study the shipway both genes and the environment influence development of behavioral phenotypes.Nature and nurtureInnate behaviors are behavior that is developmentally fixed and are under strong genetic influenceKinesis is a simple change in activity or turning rateTaxis is an oriented movement toward or away from some stimulus.Trout automatically swim or orient themselves in an upstream direction, scuppering rheotaxisBird migration is partly under genetic control.Animal communication consists of the transmission of, reception of, and response to signalsA signal is a behavior that causes a change in another animals behaviorIt is an essential element of interactions between individualsMany animals that communicate through odors pass out chemical substances called pheromonesThey are ty pically very concentratedMany animals also communicate by auditory communicationA variety of mammalian behaviors are under relatively strong genetic control.Research has revealed the genetic and neural basis for the mating and parental behavior of male prairie voles.IV. Environment, interacting with an animals genetic makeup, influences the development of behaviors. research lab experiments have demonstrated that the type of food eaten during larval development strongly influences later mate selection by Drosophila mojavensis femalesCross-fostering studies of California mice and white-footed mice have exposed an influence of social environment on the aggressive and parental behaviors of mice.Learning is the alteration of behavior based on specific experiences.Special learning is the modification of behavior based on experience with the special structure of the environmentThis makes use of landmarks, or location indicatorsA cognitive map is an internal authority or code of the spa tial relationships between objects in an animals surroundingsAssociative learning is the ability of many animals to associate one feature of the environment with anotherClassical instruct is a type of associative learning in which an arbitrary stimulus is associated with a reward or punishmentoperant conditioning is called trial-and-error learningCognition is the ability of an animals nervous system to perceive, store, process, and use information gathered by sensory receptors.The study of animal cognition, called cognitive ethology, examines the association between an animals nervous system and its behavior.Habituation is a loss of responsiveness to stimuli that convey little or no informationV. Behavioral traits can evolve by natural selection.When behavioral variation within a species corresponds to variation in environmental conditions, it may be evidence of past evolutionAn exercise of genetically based variation in behavior within a species is pretty selection by the garter snake Thamnophis elegansForaging is behavior associated with recognizing, searching for, capture, and consuming foodLaboratory studies of Drosophila communitys raised in high and low density conditions show a clear divergence in behavior linked to specific genesD. melangogaster living at low universe density followed a foraging path shorter than that of D. melanogaster living at high existence densityVI. Natural selection favors behaviors that increase survival and reproductive success.Optimal foraging theory states that natural selection should favor foraging behavior that minimizes the be of foraging and maximizing the benefits.How mate choice enhances reproductive success varies, depending on the species mating system.In promiscuous mating, there are no strong duette bonds or lasting relationshipsIn monogamous mating, one male mates with one femaleIn polygamous mating, an individual of one sex mates with several of the otherIn polygyny, one males mates with many femalesIn po lyandry, one female mates with several malesMales competition for mates is a source of intrasexual selection that can reduce variation among malesagonistic behavior is an often ritualized contest that determines which competitor gains access to a resource, such as food or matesGame 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.VII. The concept of inclusive fitness can account for most altruistic social behavior.On occasion, animals behave in altruistic ways that reduce their individual fitness but increase the fitness of the recipient of the behavior.For example, if a squirrel sees a predator approach, the squirrel gives off an alarm, alerting unaware individuals but increasing the risk to itselfThis behavior can be explained by the concept of inclusive fitnessIt is the total effect an individual has on proliferating its genes by producing its own payoff and by providing aid that enables other close relatives to produce offspringThe three key variables in an act of altruism are the benefit to the recipient (B), the cost to the altruist (C), and the coefficient of relatedness (r).Hamiltons rule states that rB CKin selection favors altruistic behavior by enhancing the reproductive success of relativesAltruistic behavior toward unrelated individuals can be adaptive if the help individual returns the favor in the future, an exchange of aid called reciprocal altruism.Social learning forms the roots of culture, which can be be as a system of information transfer through observation or teaching that influences the behavior of individuals in a population.Male choice copy is a behavior in which individuals in a population copy the mate choice of othersHuman culture is related to evolutionary theory in the discipline of sociobiology, whose main forego is that certain behavior characteristics exist because they are expressions of ge nes that have been perpetuated by natural selection.Ch. 52I. Population ecology is the study of populations in relation to the environment, including environmental influences on population density and distribution.A population is a group of individuals of a single species living in the same general areaII. Dynamic biological processes influence population density, dispersion, and demography.Population density, the number of individuals per area or volume, results from the combination of births, deaths, immigration, and emigration.Dispersion is the pattern of spacing among individuals within the boundaries of the populationEnvironmental and social factors influence the spacing of individualsIn clumped patterns, individuals are aggregated in patchesIn uniform patterns, individuals are evenly spacedAnimals often exhibit uniform dispersion as a result of antagonistic social interactions, such as territoriality, the defense of a bounded physical space against irreverence by other indivi dualsIn random dispersion, individuals are unpredictably spaced, and the position of each individual is independent of othersThis occurs in the absence of strong attraction or repulsions among individuals of a populationPopulations fester from births and immigration and shrink from deaths and emigrationImmigration is the influx of new individuals from other areasEmigration is the movement of individuals out of a populationDemography is the study of the brisk statistics of populations and how they change over timeOf particularly interest to demographers are birth rates and how they vary among individuals and death rates life couplet tables are period-specific summaries of the survival pattern of a populationthe best way to construct one is to follow the fate of a cohort, a group of individuals of the same age, from birth until all are deadA survivorship curve is a plot of the proportion or numbers in a cohort gloss over alive at each ageIdealized survivorship curvesType I curve i s flat at the start, reflecting low death rates during early and lay life, then drops steeply as death rates increase among older age groupsType II curves are intermediate, with a constant death rate over the organisms life spanType III curve drops sharply at the start, reflecting very high death rates for the young, but the flattens out as death rates fall for those individuals that have survived to a critical ageReproductive tables, or fertility schedules, are age specific summaries of the reproductive rates in a populationIII. The traits that affect an organisms schedule of reproduction and survival from birth through reproduction to death make up its life history.They are evolutionary outcomes reflected in the development, physiology, and behavior of an organism.Semelparous organisms reproduce a single time and die.When the survival rate of offspring is low, as in highly variable or unpredictable environments, this is favoredIteroparous organisms produce offspring repeatedly.Wh en environments are dependable and where competition for resources may be intense, this is favored.Life history traits such as brood size, age at maturity, and parental caregiving represent trade-offs between conflicting demands for limited time, energy, and nutrients.IV. The exponential model describes population growth in an idealized, unlimited environment.The per capita birth rate (b) is the number of offspring produced per unit time by an average member of the populationThe per capita death rate (m) is the number of individuals of a population that die per unit timeThe per capita rate of increase (r), or a populations growth rate, equals birth rate minus death rate.R = b mGrowth occurs when r0 and decline occurs when r CKin selection favors altruistic behavior by enhancing the reproductive success of relativesAltruistic behavior toward unrelated individuals can be adaptive if the aided individual returns the favor in the future, an exchange of aid called reciprocal altruism.So cial learning forms the roots of culture, which can be defined as a system of information transfer through observation or teaching that influences the behavior of individuals in a population.Male choice copying is a behavior in which individuals in a population copy the mate choice of othersHuman culture is related to evolutionary theory in the discipline of sociobiology, whose main premise is that certain behavior characteristics exist because they are expressions of genes that have been perpetuated by natural selection.Ch. 52I. Population ecology is the study of populations in relation to the environment, including environmental influences on population density and distribution.A population is a group of individuals of a single species living in the same general areaII. Dynamic biological processes influence population density, dispersion, and demography.Population density, the number of individuals per area or volume, results from the combination of births, deaths, immigration, a nd emigration.Dispersion is the pattern of spacing among individuals within the boundaries of the populationEnvironmental and social factors influence the spacing of individualsIn clumped patterns, individuals are aggregated in patchesIn uniform patterns, individuals are evenly spacedAnimals often exhibit uniform dispersion as a result of antagonistic social interactions, such as territoriality, the defense of a bounded physical space against encroachment by other individualsIn random dispersion, individuals are unpredictably spaced, and the position of each individual is independent of othersThis occurs in the absence of strong attraction or repulsions among individuals of a populationPopulations grow from births and immigration and shrink from deaths and emigrationImmigration is the influx of new individuals from other areasEmigration is the movement of individuals out of a populationDemography is the study of the vital statistics of populations and how they change over timeOf par ticularly interest to demographers are birth rates and how they vary among individuals and death ratesLife tables are age-specific summaries of the survival pattern of a populationthe best way to construct one is to follow the fate of a cohort, a group of individuals of the same age, from birth until all are deadA survivorship curve is a plot of the proportion or numbers in a cohort still alive at each ageIdealized survivorship curvesType I curve is flat at the start, reflecting low death rates during early and middle life, then drops steeply as death rates increase among older age groupsType II curves are intermediate, with a constant death rate over the organisms life spanType III curve drops sharply at the start, reflecting very high death rates for the young, but the flattens out as death rates decline for those individuals that have survived to a critical ageReproductive tables, or fertility schedules, are age specific summaries of the reproductive rates in a populationIII. The traits that affect an organisms schedule of reproduction and survival from birth through reproduction to death make up its life history.They are evolutionary outcomes reflected in the development, physiology, and behavior of an organism.Semelparous organisms reproduce a single time and die.When the survival rate of offspring is low, as in highly variable or unpredictable environments, this is favoredIteroparous organisms produce offspring repeatedly.When environments are dependable and where competition for resources may be intense, this is favored.Life history traits such as brood size, age at maturity, and parental caregiving represent trade-offs between conflicting demands for limited time, energy, and nutrients.IV. The exponential model describes population growth in an idealized, unlimited environment.The per capita birth rate (b) is the number of offspring produced per unit time by an average member of the populationThe per capita death rate (m) is the number of individuals o f a population that die per unit timeThe per capita rate of increase (r), or a populations growth rate, equals birth rate minus death rate.R = b mGrowth occurs when r0 and decline occurs when r