* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapters 42
Survey
Document related concepts
Biogeography wikipedia , lookup
Island restoration wikipedia , lookup
Restoration ecology wikipedia , lookup
Homeostasis wikipedia , lookup
Reconciliation ecology wikipedia , lookup
Habitat conservation wikipedia , lookup
Renewable resource wikipedia , lookup
Ecological fitting wikipedia , lookup
Biodiversity action plan wikipedia , lookup
Transcript
Chapter 42: Circulation And Gas Exchange Most invertebrates have a gastronomical cavity or a circulatory system for internal transport Gastrovascular cavities- A body wall only two cells thick encloses a gastronomical cavity, which servers the dual functions of digestion and substance distribution in the body. Open and Close Circulatory systems Hemolymph- general body fluid Open circulatory system- In insects and arthropods, and most mollusks, blood bathes the internal organs directly Sinuses- Spaces surrounding the organs Closed circulatory system- blood confined to vessels and has a heart pumping blood to different systems Vertebrate phylogeny is reflected in adaptations of the cardiovascular system FISH AMPHIBIAN MAMMAL Cardiovascular system- made up of the heart, blood vessels, and blood Atrium(Atria)- The chambers that receive blood returning to the heart Ventricles- The chambers that receive blood returning to the heart Arteries- carry blood away from the heart to other organs Arterioles- Branches of the arteries that convey blood into the capillaries Capillaries- microscopic vessels with very thin, porous walls Capillary beds- networks of capillaries where chemicals and gasses are exchanged between the blood and interstitial fluid Venules- The ending of capillaries that converge into veins Veins- return blood to the heart Pulmocutaneous circuit- frogs and other amphibians that have a three-chambered heart, and this circuit leads to gas exchange tissues where the blood picks up oxygen as it flows through capillaries 壱 Systemic circuit- carries oxygen-rich blood to all body organs then returns oxygenpoor blood to all body organs Double circulation- ensures a vigorous flow of blood to the brain, muscles, and other organs Pulmonary circuit- in reptiles, blood is conveyed from the heart to the gas-exchange tissues in lungs and back to the heart Double circulation in mammals depends on the anatomy and pumping cycle of the heart The Mammalian Heart: A closer look 1) The right ventricle pumps blood to the longs via the pulmonary arteries 2) Blood flows through the capillary beds in lungs where it loads up on Oxygen and gets rid of Carbon Dioxide 3) It returns from the lungs via the pulmonary veins to the left atrium of the heart 4) The oxygen-rich blood flows into the left ventricle Atrioventricular (AV) valve- anchored by strong fibers, strong contractions of the ventricles closes the AV valves, keeping blood from flowing back into the atria. Semilunar valves- located at the two exits of the heart. The blood is pumped into the arteries, via these valves, and is forced open when the pressure is created by ventricular contraction. Pulse- the rhythmic stretching of the arteries caused by the pressure of blood driven by the powerful contractions of the ventricles Heart Rate- the number of times the heart beats each minute Cardiac cycle- one complete cycle of pumping and filling Systole- a contraction phase Diastole- a relaxation phase Cardiac output- the volume of blood per minute that the left ventricle pumps into the systematic circuit Stroke volume- the amount of blood pumped by the left ventricle each time it contracts Maintaining the Heart’s Rhythmic Beat1) The SA node sets the tempo of the heartbeat by generating electrical signals 2) The electrical signals are spread through the atria, making them contract simultaneously. At the AV node, there is a slight delay where the blood in the atria empties into the ventricles 弐 3) Specialized muscle fibers (bundle branches and Purkinje fibers) then conduct the signals to the apex of the heart and ventricular walls 4) The signals trigger both ventricles to powerfully contract, driving blood into the large arteries Sinoatrial (SA) node (Pacemaker)- a region of the heart that maintains the heart’s pumping rhythm by setting the rate at which all cardiac muscles cells contract Atrioventricular (AV) Node- a relay point where the impulses from the SA node go. The impulses are delayed for about .1 sec, which make sure the atria will contract and then empty before the ventricles contract. Electrocardiogram (ECG or EKG)- electrodes placed on the skin and record the electrical currents of the body Structural differences of arteries, veins, and capillaries vessels correlated with their different functions Endothelium- a single layer of flattened cells that provides a smooth surface that minimizes resistance to the flow of blood Physical laws governing the movement of fluids through pipes affect blood flow and blood pressure Capillaries- lack 2 outer layers, very thin walls (only basement membrane and endothelium) Arteries- thicker middle and outer layers than veins Blood Pressure Blood Pressure- the hydrostatic force that blood exerts against the wall of a vessel Peripheral resistance- the impendence by the arterioles Transfer of substances between the blood and the interstitial fluid occurs across the thin walls of the capillaries - At any given time, only about 5%-10% of the body’s capillaries have blood flowing through them A) When the precapillary sphincters are relaxed, capillaries branching from the thoughtfare channel are open, and blood flows into the capillary bed B) When the sphincters are contracted, the capillaries are closed, and blood flows through the capillary bed is reduced - Small molecules diffuse through the membrane of the cells, such as Oxygen and CO2The lymphatic system returns fluid to the blood and aids in body defense Lymphatic system- lost fluid and proteins return to the blood by diffusing into tiny lymph capillaries that are intermingled among capillaries of the cardiovascular system Lymph- fluid inside the lymphatic system Lymph nodes- organs along a lymph vessel where filter the lymph. Plasma- vertebrate blood is a type of connective tissue consisting of several kids of cells suspending in a liquid matrix Red Blood cells (erythrocystes)- the most numerous of the blood cells, that transports oxygen and helps transports Carbon Dioxide Hemoglobin- an oxygen carrying protein containing iron White blood cells (Leukocytes)- helps with defense and immunity 参 Platelets- blood clotting Pluripotent stem cells- a single population of cells in the red marrow of bones (ribs, vertebrate, breastbone, pelvis) Erythropoietin- a hormone that stimulates production of erythrocytes in the bone marrow Fibrinogen- a sealent for vessels Fibrin- a plasma protein is converted to its active form which aggregates threads that form the fabric of the clot Hemophilia- a disease characterized by excessive bleeding from even minor cuts and bruises Thrombusvascular diseases – disease of the heart and blood vessels Heart Attack- the death of cardiac muscle tissue resulting from prolonged blockage of one or more coronary arteries Stroke- the death of nervous tissue in the brain, usually resulting from blockage of arteries in the head Hypertensions- high blood pressure that increases the risk of heart attack and stroke GAS EXCHANGE IN ANIMALS (Pulled from another website) Animals require oxygen because O2 is the final electron acceptor in the electron transport chain, a metabolic pathway used by organisms to generate the bulk of their ATP Without continuous supply of O2 they cannot not obtain enough energy from their food to remain alive. Energy metabolism also generates CO2 as waste. Respiratory surface = part of animal where O2 diffuses into the animal and CO2 diffuses out into the environment. 4 types of animal respiratory systems evolved 1. Entire outer skin: small animals, worms, flat worms, planarians, hydra; must live in wet places; have enough surface to volume ratio. 2. Gills: feather-like extensions of body surface specialized for gas exchange; evolved and are present in most aquatic animals (Fig 42.19). 3. Trachea: respiratory surface of insects; made up of extensive system of internal tubes leading to several openings on body surface; variation on theme of folded internal respiratory surface 4. Lungs: most terrestrial vertebrates have them; made up of internal sacs lined with moist epithelium. Tracheal system of insects is made up of tubes that branch out throughout the body Mammalian respiratory system Air enters the lung through a system of branching tubes when chest cavity increases in volume as a result of muscular contractions by diaphragm and rib muscles With exception of smallest bronchioles and alveoli, most epithelial cells lining respiratory tract are covered with cilia and thin film of mucus trachea; wind pipe; lined by cartilaginous rings to maintain shape. bronchus 1 per lung. Splits into bronchioles bronchiole; continue to split and become smaller until they terminate as alveoli 四 alveoli: grape-like clusters of air sacs at ends of small bronchioles; surface where gas exchange is actually carried out; highly capillarized. capillaries; exchange gases with epithelial cells lining alveoli. 1. inhalation: sucking-in of air; chest cavity increases in size due to contraction of diaphragm and rib muscles resulting in a decrease in air pressure in the lungs. Air flows down its pressure gradient into lungs. 2. exhalation; relaxation of diaphragm and rib muscles decrease s size of chest cavity, causing air to be expelled. tidal volume = vol of air that animal inhales and exhales in each normal breath ( ~500ml) Vital capacity = max volume of air that we can inhale and exhale (strenuous exercise.) (3500-4800 ml ) 500 ml breathing at rest Residual volume = air that remains in the lung after forcefully blowing out as much air as posssible. i.e lungs hold more volume than vital capacity due to dead air in uncollapsed alveoli. Emphysema = loss of resilience of in lung cells. Smoking makes walls of alveoli brittle (lose elasticity) and some rupture, leading to reduced capacity for gas exchange. Hyperventillation = breathing control centers no longer send signals to muscle cells because rapid breathing purged too much CO2 from the body. Gases diffuse down pressure gradients in the lungs and other organs Partial pressure = portion of atmospheric pressure contributed by a certain gas. Disorders of the Respiratory system Reduced air flow or gas exchange impedes respiratory function. Asthma: Spasmodic contraction of bronchi; reversible decrease in gas exchange surface; becoming more common;bronchodialators standard therapy. Emphysema: Alveoli become permanently impaired as result of loss of elasticity; permanent decrease in gas respiratory surface; common in smokers; leads to cardiovascular disease. Bronchitis: inflamation of bronchi; heavy mucous and cough; common in smokers. Pneumonia: inflamation of lungs due to infection; viral or bacterial. Tuberculosis: infectious lung disease caused by Mycobacterium tuberculosis; easily treatable, but becoming more common. Botulism: form of food poisoning caused by Clostrridium botulinum; toxin blocks transmission of nerve signals to skeletal muscles. Congestive heart failure: backpressure from heart moves fluids into the lungs Cystic fibrosis: Defective ion channel upsets water relations; excessive build up of mucus in bronchi and parabronchi; most common genetic disorder in N. America; recessive. 伍 Chapter 48: Nervous SystemsNervous systems perform the three overlapping functions of sensory input, integration, and motor output Central nervous system (CNS)- the brain and spinal cord Effector Cells- the muscle cells or gland cells that actually carry out the body’s responses to stimuli Neuron-the functional unity of the nervous system specialized for transmitting signals from one location in the body to another Peripheral nervous system (PNS)- the nerves that communicate motor and sensory signals between the CNS and the rest of the body Dendrites- convey signals from their tips to the rest of the neuron Axons- which conduct messages toward their tips Myelin Sheath- an insulating layer that enclose the vertebrate nervous system Schwann cells- supporting cells that form myelin sheaths Oligodendrocytes- supporting cells that help to produce the myelin sheaths Synaptic terminals- endings of the axons that relay signals to other cells be releasing chemical messengers called neurotransmitters Synapse- The site of contact between a synaptic terminal and a target cell Sensory Neurons- communicate information about the external and internal environments from sensory receptions to the CNS Interneurons—integrate sensory input and motor output (they make synaptic connections only with other neurons) Motor neurons- convey impulses from the CNS to effector cells 六 Chapter 49: Sensory And Motor Mechanisms Hydrostatic skeletons Hydrostatic skeleton- consists of fluid held under pressure in a closed body compartment, the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids Peristalis- a type of locomotion produced by rhythmic waves of muscle contractions massing from head to tail (earthworms) Exoskeleton- a hard encasement deposited on the surface of an anima (Mollusk, beetles) Cuticle- a nonliving coat secreted by the epidermis Chitin- a polysaccharide similar to cellulose Endoskeleton – consists of hard supporting elements, such as bones, buried within the soft tissues of an animal Skeletal Muscle- attached to the bones and is responsible for their movement Myofibrils- tiny fibers that are in skeletal fibers Myofilaments- Two types of filaments- thick and thin, Thin filaments- actin and regularatory proteins collided around each other Thick filaments- myosin molecules Sarcomere- the basic functional unit of the muscle, a repeating pattern of dark and light lines Z lines- the borders around the sarcomere, I band- the area near the edge of the sarcomere where there are only thin filaments 七 A band- the broad region that corresponds to the length of the thick filaments H zonethe center of the A band that contains only thick filaments Sliding-filament model- the thin and thick filaments do not get smaller, they just slide past each other when the muscle contracts. Cross-Bridge- the sites where energized myosin binds to a specific site on the actin Phosphagens- where muscle cells store glycogen needed for repetitive muscle contractions Creatine Phosphate- the phosphagens of vertebrates, can supply a phosphate group to ADP to make ATP Calcium Ions and regulatory proteins control muscle contraction Tropomyosin- the regulatory protein that blacks the myosin binding sites on the actin molecules Troponin complex- controls the position of tropomyosin on the thin filament Sacroplasmic reticulum- a specialized endoplasmic reticulum that transports calcium from the cytoplasm into the interior of the reticulum T (Transverse) tubules- infoldings of the plasma membrane where the tubules contact the sarcoplasmic reticulumDiverse body movements require variation in muscle activity Motor unit- consists of a single motor neuron and all the muscle fibers it controls Recruitment- tension in a muscle that can be increased by activating more and more of the motor neurons controlling the muscle Fast and Slow Muscle Fibers Fast Muscle fibers- used for rapid, powerful contractions Slow muscle fibers- can sustain long contractions, often found in muscles that maintain posture 八 Other types of muscle Cardiac Muscle- found only in the heart, striated Intercalated discs- junctions between cardiac muscles cells where gap junctions can provide direct electrical coupling among cells Smooth Muscle- lacks the striations of skeletal and cardiac muscle Chapter 50: An introduction to ecology and the biosphere Ecology is the scientific study of the interactions between organisms and their environment Abiotic components- nonliving chemical and physical factors (light, temperature, water, nutrients) Biotic components- all the other organisms that are part of any individual’s environments Ecological research ranges from the adaptations of organisms to the dynamics of ecosystems Organismal ecology- concerned with the behavioral, physiological, and morphological ways in which individual organism meet that challenges posed by their abiotic environment Population- a group of individuals of the same species living in a particular area Community- consists of all the organism that inhabit a particular area Ecosystem- a study that includes all abiotic factors in addition to the community of species that exists in a certain area ABIOTIC FACTORS OF THE BIOSPHERE Biosphere- the global ecosystem, the sum of all the planet’s ecosystems, or all of life and where it lives Climate and other abiotic factors are important determinates of the biosphere’s distribution of organisms. Major abiotic Factors 九 TEMPERATURE- Certain organisms need certain temperatures to live in; most organisms cannot live in extreme high or low temperatures. Organisms function best within certain environmental temperatures WATER- The availability of water varies among habitats, and most habitats are shaped by organisms requirements for obtaining and conserving water supplies SUNLIGHT- Provides the energy to fuel most ecosystems, although only photosynthetic organisms use the sun directly. WIND- Amplifies the environmental temperature, contributes to water loss by increasing the rate of evaporation, hold an effect on growth form of plants ROCKS AND SOIL- Physical structure, pH, and mineral composition of rocks and soil limit plant distribution, animals that feed off of them. PERIODIC DISTRUBANCES- Hurricanes, fires, volcanic, tornadoes, and other disturbances Climate and the distribution of organisms Climate- the prevailing weather conditions at locality, affected by water, light, and wind, and temperature Biome- A major type of ecosystem, those that occupy geographic regions Global Climate Patterns Tropics- regions between 23.5 N latitude and 23.5 S latitude Local and Seasonal Effects on Climate Turnover- during the summer and winter, many lakes in temperate regions are thermally stratified, of layered vertically, according to temperature. Such lakes undergo a biannual mixing of their waters as a result of changing water-temperature profiles. It brings oxygenated water from the surface of lakes to the bottom and nutrient rich water from the bottom to the top AQUATIC AND TERRESTRIAL BIOMES Aquatic biomes occupy the largest part of the biosphere Vertical stratification of aquatic biomes Photic zone- where there is sufficient light for photosynthesis Aphotic zone- little light penetrates 壱拾 Thermocline- a narrow stratum of rapid temperature change that separates a more uniformly warm upper layer from more uniformly cold deeper waters Benthos- a community of organism in the benthic zone Benthic zone- the substrate at the bottom of all aquatic biomes Detritus- a source of food for the benthos that is made up of dead organic matter Freshwater Biomes Littoral Zone- the shallow, well-lit waters close to shore Limentic zone- open surface waters further from shore Profundal Zone- deep aphotic zone Oligotrophic- a type of lake that is deep and nutrient poor Eutrophic- usually more shallow that oligotrophic, and have a high nutrient content Mesotrophic- In between the oligotrophic and eutrophic levels of deepness and nutrient content Wetland- an area covered with water that supports aquatic plants Estuary- the area where a freshwater stream or river merges with the ocean, often bordered by extensive coastal wetlands called mudflats and salt marshes 壱拾壱 Intertidal zone- Zone where land meets water Neritic Zone- the shallow regions over the continental shelf Oceanic zone- past the continental zone that reaches very deep Pelagic zone- the open water of any depth Benthic Zone- the bottom of the seafloor Oceanic pelagic biome- most of the ocean’s water, far from shore, that is constantly mixed by ocean currents Benthos Abyssal Zone- the deep benthic zone, where organisms are adapted to cold, high water pressure, and near or total absence of light, and low nutrient content. -Here, there are chemoautotrophic prokaryotes The geographical distribution of terrestrial biomes is based mainly on regional variations in climate Canopy- the upper part of the forest, the top layers of the trees that cover the entire forest Permafrost- permanently frozen stratum 壱拾弐 CONCEPTS OF ORGANISMAL ECOLOGY The costs and benefits of homeostasis affect an organism’s responses to environmental variation Regulators- they use behavioral and physiological mechanisms to achieve homeostasis in the face of environmental fluctuations in temperature, moisture, light intensity, and concentrations of a variety of chemical factors A) Tropical Forests- Rainfall is extremely variable, prime determinate of the vegetation growing there. Plants are thorny shrubs, trees and succulents. In areas with distinct wet and dry seasons, tropical deciduous trees are common B) Savanna- Large showcase of large herbivores and their predators, many insects, ants and termites. Grasses and scattered trees, fire is an important factor as many things are fire-adapted. Often periods of seasonal drought C) Desert- Some rainfall, cacti, rooted shrubs, many plants use CAM photosynthesis, many protective adaptations deter mammals and insects feeding on them (spines and poisons) D) Chaparral – Dense, spiny, evergreen shrubs, mild rainy winters, and long, hot, dry summers, often brushfires, so things are adapted to that, some seeds can only germinate after a hot fire. E) Temperate Grassland- Plains and prairies, seasonal drought, occasional fires, large mammals, few woody shrubs and trees, soil is often deep and rich in nutrients 壱拾参 F) Temperate Deciduous Forest- Dense strands of deciduous trees, distinct layers and seasons G) Coniferous Forest- cone bearing trees, pine, spruce, fir, and hemlock, frequently logged H) Tundra- permafrost, bitterly cold temperature, high winds, shallow topsoil Conformers- organisms that call allow some conditions within their bodies to vary with external changes Principle of allocation- organisms have a limited amount of energy that can be allocate for obtaining nutrients, escaping from predators, coping with environmental fluctuations, growth, and reproduction Acclimation- involves substantial but reversible change that shift an organisms tolerance curve in the direction of the environmental change Chapter 52 Population Ecology Two important characteristics of any population are density and the spacing of individuals Population- a single species that occupy the same area Density- the number of individuals per unit area or volume Dispersion- the pattern of spacing among individuals within the geographical boundaries of the populations Measuring Density Mark-Recapture Method- tagging a certain amount, and then using (number marked times total catch second time) divided by number of marked recaptures Patterns of Dispersion Grain- one which the environmental patches are so large that an individual organism can distinguish and chose among patches Clumped- Strong attractions to each other Uniform- evenly spaced organisms 壱拾四 Random- random spacing, with no strong attraction or repulsion Biogeography- the factors that influence the distribution of a species over its range are the subject Demography is the study of factors that affect the growth and decline of populations Demography- the study of vital statistics that affect population size Age Structure and Sex Ratio Age Structure- the relative number of individuals of each age Birthrate (Fecundity)- the number of offspring produced during a certain amount of time Death Rate- the number of deaths in a certain amount of time Generation Time- the average span between the birth of individuals and the birth of their offspring Sex Ratio- the proportion of individuals of each sex Cohort- a group of individuals of the same age, from birth, until death Survivorship Curve- a plot of the numbers in a cohort still alive at each age LIFE HISTORY TRAITS Life History- the traits that affect an organism’s schedule of reproduction and death Number of reproduction episodes per lifetime 壱拾伍 Smeelparity- expend their energy in one large reproductive effort, and then die Iteroparity- organisms that produce fewer offspring at a time over a span of many seasons An exponential model of population growth describes an idealized population in an unlimited environment Intrinsic Rate of increase- the maximum population growth rate Exponential population growth- population increase under certain conditions A logistic model of population growth incorporates the concept of carrying capacity Carrying capacity- the maximum population size that a particular environment can support with no net increase or decrease over a relatively long period of time Logistic population growth- incorporates the effect of population density Population Growth Models and Life Histories Equilibrial populations (k-selected- are those that are likely to be living at density near the limit imposed by their resources Opportunistic populations (r-selected)- likely to be found in variable environments in which population densities fluctuate POPULATION LIMITING FACTORS Density-Dependent Factors regulate population growth by varying with the density Intraspecific competition- the reliance of individuals of the same species on the same limited resources Density-Dependent factor- one that intensifies as the population increases in size The occurrence and severity of density-independent factors are unrelated to population density Density-independent factors- unrelated to population size 壱拾六 Chapter 53: Community Ecology Species Richness- the number of species contained Species diversity- the species richness and relative abundance The interactive and individualistic hypotheses pose alternative explanations of community structure: science as a process Individualistic hypothesis- Gleason’s idea that community was a chance assemblage of species found in the same area simply because they happen to have similar abiotic requirements (temp, rainfall, soil type) Interactive hypothesis- Clement’s idea was that the community was an assemblage of closely linked species that cause the community to function as an integrated unit INTERACTIONS BETWEEN POPULATIONS OF DIFFERENT SPECIES Coevolution- describes interactions involving reciprocal evolutionary adaptations in two species Interspecific interactions may have positive negative, or neutral effects on a population’s density: on overview 壱拾七 Interaction Predatation +/Commensalism +/o Competition -/Mutualism +/+ Effects on Population Density Helps one, hurts the other One species helps the other is unaffected Both are hurt Both are helped Predication and parasitism are +/- interactions: a closer look Predatation- a predator and prey relationship Parasitism- specialized kinds of predators called parasites that live in or on their hosts Parasitoidism- insects that lay eggs on living hosts Herbivory- animals eating plants Plant Defense Against Herbivores - Some plants store poisons, other chemical weapons of defense Animal Defenses Against Predators Cryptic Coloration- camouflage can make the potential prey difficult to spot against its background Aposematic coloration- a warning to predators by taking on bright warning colors - Deceptive coloring can resemble the eyes of a much larger animals or something else Mimicry- an organisms bears superficial resemblance to another species Batesian mimicry- a palatable or harmless species mimics a harmful model Mullerian mimicry- two ore more unpalatable, aposematically colored species that resemble each other Parasitisim Endoparasites- parasites that live inside their hosts Ectroparasites- parasites that feed on the external surface of a host Interspecfic competitions are -/- interactions: a closer look Interspecific competition- populations of two or more species in a community rely on similar limiting resources 壱拾八 Interference competition- competition that can occur in different ways Exploitive competition- the consumption or use of similar resources The competitive exclusion principal Competitive exclusion principle – the idea that when two organisms exist and compete against each other, one of them will perish Ecological Niches Ecological niche- the sum total of the organism’s use of the biotic and abiotic resources in its environment Fundamental Niche- refers to the set of resources a population is theoretically capable of using under ideal circumstances Evidence for Competition in Nature Resource partitioning- sympatric species consume slightly different foods or use other resources in slightly different ways Character displacement- the idea that characteristics tend to be more divergent in sympatric populations of two species than in allopatric populations Commensalism and mutualism are +/0 and +/+ interactions, respectively: a closer look Symbiosis – ‘living together’ is a term that encompasses a variety of interactions in which two species host and symbiotic, maintain a close association Parasitism- one organism harms the host Commensalism- one partner is benefit, the other one isn’t affected Mutualism- both partners benefit Predators can alter community structure by moderating competition among prey species Keystone species- a species that makes an unusually strong impact on community structure DISTURBANCE AND NONEQUILIBRIUM 壱拾九 Stability- the context is the tendency of a community to reach and maintain an equilibrium Nonequilibrium resulting from disturbance is a prominent feature of most communities Disturbances- the events, such as storms, fire, floods, droughts, and overgrazing that damage communities Succession is a process of change that results from disturbances in communities Ecological succession- transitions in species composition over ecological time represent a process Primary Succession- the process where a lifeless area springs life Secondary succession- occurs where an existing community has been cleared by some disturbance that leaves the soil intact The nonequilibrial model views communities as mosaics of patches at different stages of succession Recruitment- disturbances that trigger major changes in community structure generally are those whose magnitude or frequency results in colonization of disturbed patches Dynamic Equilibrium Hypothesis- species diversity depends mainly on the effect of disturbance on the competitive interactions of populations Intermediate disturbance hypothesis- species diversity is greatest where disturbances are moderate in both frequency and severity COMMUNITY ECOLOGY AND BIOGEOGRAPHY Dispersal and survivability in ecological and evolutionary time account for the geographical ranges of species 弐拾 Chapter 54: Ecosystems Trophic Structure- feeding relationships Trophic levels- basis of organisms main source of nutrition Trophic relationships determine an ecosystem’s routes of energy flow and chemical cycling Primary Producers- autotrophs, that use light energy to make sugars and other organic compounds Primary Consumers- Herbivores, which eat plants or algae Secondary Consumers- carnivores that eat herbivores Tertiary Consumers- carnivores that eat other carnivores Detritivores- consumers that derive their energy from detritus Detritius- non living organic material, such as feces, fallen leaves, and the remains of dead organisms Food Chain- the pathway along which food is transferred from trophic level to trophic level Food Webs- feeding relationships, the producer- primary consumer secondary consumer Production- the rate of incorporation of energy and materials into the bodies of organisms Consumption- loosely defined by generally refers to metabolic use for growth and reproduction of assimilated organic materials Decomposition- the breakdown of organic materials to inorganic ones Primary Producers include plants, algae, and many species of bacteria - Limnetic Zone- phytoplankton - Aphotic zone- deep sea, that depends on the photic zone 弐拾壱 Primary Productivity Primary Productivity- amount of light energy converted to chemical energy by the autorophs of an ecosystem Gross Primary Productivity (GPP)- another word for the primary productivity Net Primary Productivity (NPP)- equal to the gross primary productivity Biomass- energy per unit area per unit time Standing crop biomass- total biomass of photosynthetic autorophs present at a given time Limiting nutrient- the single nutrient that runs out of adequate supply first As energy flows through an ecosystem, much is lost at each trophic level Secondary Productivity 弐拾弐 Secondary Productivity- the rate at which an ecosystem’s consumers convert the chemical energy of the food they eat into their own new biomass Ecological Efficiency and Ecological Pyramids Ecological Efficiency- the percentage of energy transferred from one trophic level to the next Pyramid of productivity- the multiplicative loss of energy from a food chin, where the trophic levels are stacked in blocks Biomass pyramid- each tier represents the standing crop biomass Turnover time- the lower standing crop biomass compared to productivity Pyramid of numbers- the size of each block is proportional to the number of individual organisms present in each trophic level CYCLING OF CHEMICAL ELEMENTS IN ECOSYSTEMS The Water Cycle The Carbon Cycle 弐拾参 The Nitrogen Cycle Nitrogen Fixation- convert N2 into minerals that can be used to synthesize nitrogenous organic compounds Nitrification- turning ammonium to nitrite to nitrate (No2) to (NO3) Denitrification- some nitrate is turned back to N2 Ammonification- process of decomposition of organic nitrogen back to ammonium The Phosphorus Cycle Field experiments reveal how vegetation regulates chemical cycling: science as a process Long-Term ecological research (LTER)their job is to track the dynamics of natural ecosystems over relatively long periods of time 弐拾四 Chapter 55: Conservation Biology The major threats to biodiversity and habitat destruction, overexploitation, and competition by exotic species - The Nile Perch- introduced into Lake Victoria, and the introduced perch annihilated the cichlid populations, destroying the native fish and its own food supply - March of the Fire ants- accidentally imported and spread through the Eastern United States in a short amount of years 1956-1994 Biodiversity is vital to human welfare - The rosy periwinkle, helps to sure Hodgkin’s disease and acute lymphocytic leukemia THE GEOGRAPHIC DISTRIBUTION OF BIODIVERSITY Gradual variation in biodiversity correlated with geographical gradients 1. Energy availability- increased solar radiation in the tropics increases the photosynthetic activity of plants, providing an increases resources base for other organisms and thus a capacity to sustain more species 2. Habitat heterogeneity- compared to other areas, tropical regions commonly experience more local disturbances, and have greater environmental patchiness, allowing a greater diversity of plant species to form the resources base for diverse communities of animals 3. Niche specialization- tropical climates may allow many organism to specialize on a narrower range of resources. 4. Population interactions diversity is, in a sense, self-propagating because complex population interactions coevolved and the resulting predator-prey and symbiotic interactions in a diverse community prevent any populations from becoming dominant Biodiversity hot spots have high concentrations of endemic species -Biodiversity Hot spot- Any area that is relatively small but with an exceptional concentration of species Endemic species- species that are found in only one place and nowhere else -Such species are normally found on islands, making them extremely likely to extinction Migratory species present special problems in conservation - The Monarch butterflies are hard because they migrate from the United States to Canada, and then to Mexico and California, so conservation efforts must take place in all of their migratory locations CONSERVATION AT THE POPULATION AND SPECILES LEVELS 弐拾伍 Endangered species- an animal that is ‘in danger of extinction throughout all or a significant portion of its range’ Threatened Species- any animals that are likely to become endangered in the foreseeable future The dynamics of subdivided populations apply to problems caused by habitat fragmentation Metapopulation- a subdivided population of a single species, and vary depending in part on the size, quality, spatial arrangement, and persistence of habitat patches - Often happens when human activity interferes and cuts off part of the population from the other, essentially separating the species Source and Sink Dynamics in Metapopulations Source Habitat- an area of a habitat where a population’s reproductive success exceeds morality and from which excess individuals disperse Sink Habitat- a habitat where mortality exceeds reproductive success Population viability analyses examine the chances of a species persisting or becoming extinct in the habitats available to it Population viability analysis (PVA)- a method of predicting whether or not a species will persist in a particular environment - Takes into account genetic variability, life history characteristics, sex rations, age at first reproductions, fecundity, average birthrates, average death rates Estimating minimum viable population size (MVP) Minimum viable population size (MVP)- the smallest number of individuals needed to perpetuate a population Minimum dynamic area- the amount of suitable habitat needed to sustain a viable population Estimating Effective Population Size (Ne) Effective Population Size (Ne)- based off the number of adults that successfully breed Analyzing the viability of selected species may help sustain other species: science as a process 弐拾六 CONSERVATION AT THE COMMUNITY, ECOSYSTEM, AND LANDSCAPE LEVELS Landscape ecology- the application of ecological principles to the study of land use patterns Edges and corridors can strongly influence landscape biodiversity Movement corridor – a narrow strip or series of small clumps of quality habitat connecting otherwise isolated patches - Corridors can promote dispersal and help sustain metapopulations Nature reserves must be functional parts of landscapes Zoned reserve systems- protected areas are surrounded by lands that are used and altered more extensively by human activity - The challenge is to develop in the surrounding lands a social and economic climate that sustains itself while remaining compatible with the long-term viability of the protected core area Restoring degraded areas in an increasingly important conservation effort Restoration ecology- a subdivision of conservation biology that applies ecological principals in developing ways to return degraded ecosystems back to their original states Bioremediation- the use of living organisms, usually prokaryotes, fungi, or plants, to detoxify polluted ecosystems Sustainable development goals are reorienting ecological research and will require changing some human values Sustainable development- the long term prosperity of human societies and the ecosystems that support them Sustainable Biosphere Initiative- a research agenda that aims to define and acquire the basic ecological information necessary for the intelligent and responsible development, management, and conservation of Earth’s resources 弐拾七