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Transcript
Mrs. Daniels Advanced Biology April 2005 (revised April 2008) Population Ecology - Ch. 51 • The study of the numbers of individuals of a particular species at a given time and location • Includes interactions of that population with other populations and the environment Density and Dispersion • Density: the # of individuals of a particular species per unit of space • Dispersion: the spacing of those individuals • Uniform evenly distributed • Random - lack of • Clumped - most interaction between common; patchy indiv. – Result of uneven distribution of resources or asexual reproduction Dispersion of individuals within a population bluestripe snappers (Lutjanus kasmira) Schooling of some fish is an example of clumped dispersion Cape gannets (Morus capensis) These birds space their nests out evenly Growth Rate • r = growth rate in a population • Takes into consideration birth rate (natality) and death rate (mortality) • No population can increase exponentially indefinitely • Limiting factors become important • Carrying capacity (K): the largest population that can be sustained for an indefinite period of time Exponential population growth Number of bacteria (N) 1,200 1,000 800 dN = rN dt 600 400 200 0 0 2 4 6 Hours 8 10 12 Carrying capacity and logistic population growth Number of individuals (N) Carrying capacity of the environment (K) dN = rN dt Time K–N K ( ) Strategists • r-strategists: high r, small size, large # of offspring, may live in unpredictable habitats • K-strategists: have a population size near K, are larger in size, have fewer offspring, may care for their young • Which type are humans? Survivorship curves 1000 Figure 51-8 Page 1013 Number of survivors (log scale) Type I 100 Type II 10 1 Type III 0.1 Young Old Total life span Survivorship Curves • Type I: the young and those at reproductive age have a high probability of surviving while probability of surviving decreases with age • Ex. Humans and bison • Type II: probability of survival does not change with age; no age bias • Ex. Some lizards • Type III: the young are less likely to survive than those of increased age • Ex. oysters Population Size • Regulated by density-dependent and densityindependent factors • Density-dependent: factors that increase proportionally with population size • Ex. Competition • Density-independent: affect population regardless of size • Ex. Climatic factors Competition • Intraspecific: between members of same species • Interspecific: between members of different species Human Populations • Population statistics - demographics • Not all countries have the same growth rate • Less developed countries have the highest growth rate • Developed countries have a higher degree of industrialization and prosperity and have a lower growth rate • Environmental degradation is a result of overpopulation and resource consumption • Overpopulation causes over-consumption and overutilization of resources Human population growth Figure 51-13 Page 1016 Human population (billions) 6 5 1999: 6 billion 4 3 2 Black Death 1 8000 6000 4000 Time (years) 2000 BCE CE 2000 Human Population Growth • Do all countries/areas of the world have the same population growth rate? • Why or why not? • Have we reached carrying capacity on the Earth? • Scientists actually calculate K for this planet to be ____________...IF all resources were being utilized equitably Birth and death rates in Mexico, 1900 to 2000 50 Rate per 1000 population Birth rate 40 Overall population increase 30 20 Death rate 10 1900 1925 1950 Time (years) 1975 2000 Age structure diagrams Slow population growth United States Male Female Decline in population growth Germany Female Male 12 10 8 6 4 2 0 2 4 6 8 10 12 12 10 8 6 4 2 0 2 4 6 8 10 12 4 3 2 1 0 1 2 3 4 Number of people (in millions) Number of people (in millions) Rapid population growth Age Nigeria 80+ 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 Male Female Number of people (in millions) Community Ecology - Ch. 52 • In a community, populations interact in a variety of ways • NO species exists independently of other species • Niche - a species role in the community – All aspects of the organism’s existence, not just habitat – May be influenced by resources: biotic and abiotic Resource partitioning Figure 52-5 Page 1028 Cape May warbler Blackburnian warbler Bay-breasted warbler Yellow-rumped (Myrtle) warbler Black-throated green warbler Avoiding Competition Percentage of individuals of each size class G. fuliginosa G. fortis Bill depth 40 20 0 8 10 12 14 8 10 12 14 40 20 0 40 20 0 8 10 12 14 Bill depth (mm) • Character displacement: adaptation of characteristics that average bill depths of enables interspecific G. fuliginosa competition to be reduced average bill depths of G. fortis • (ex. Darwin’s finches) Effect of competition on an organism’s realized niche Species 1 Niche overlap Species 2 Niche dimension (habitat) Brown anole (Anolis sagrei) Resource use Resource use Green anole (Anolis carolinensis) Species 1 Species 2 Niche dimension (habitat) Predation • Predator: consumes members of another species • Prey: is hunted or consumed by members of another species • Defenses: • Plants - chemical (ex. Monarch’s) • Animals – “cryptic” warning coloration – mimicry Müllerian mimicry Monarch Viceroy Two species which are both harmful, poisonous, or distasteful resemble each other for an added effect of safety. Because both species are dangerous, the predators learn to avoid them much more quickly. Batesian mimicry Scarlet king snake (Lampropeltis triangulum elapsoides) Eastern coral snake (Micrurus fulvius fulvius) A defenseless species (scarlet king snake ) gains protection from predation by resembling a dangerous species (Eastern coral snake) • Herbivore• Carnivore• Omnivore- • • • • ProducerConsumerPrimary, secondary, tertiary, etc. Decomposers- Food Chains and Webs Quick review from elementary and middle school… Symbiotic Relationships • Symbiosis: bio - live sym - together • Mutualism - both benefit – Ex. Myccorrhizae facilitate mutualistic relationship between fungi and roots of some plants • Commensalism - one takes without harm – Ex. Epiphytes living on tropical trees – Spanish moss pictured to the right • Parasitism - one benefits at the other’s expense – Ex. Tracheal mite seen here Biodiversity • Biodiversity of the community is a measure of the relative importance of each species in the community • Not to be confused with species richness, which is the number of different species within a community Succession • The process of developing a community over time • One species is replaced by another • Primary - develops in a “lifeless” environment – On newly formed volcanic lava and recently glaciated rock • Secondary - a community develops where a previous community existed – Ex. Areas that have been denuded or modified by fire or agriculture (the soil remained after the fire…it was not completely barren) Ecosystems and the Biosphere Ch. 53 • We’ve already touched on part of this chapter when we dealt with food webs • We’ll continue this discussion and then focus on the BioGeoChemical cycles • Carbon, Nitrogen, Phosphorus, and Water Cycles are central to life on Earth Energy flow through ecosystems Energy from sun First Second Third Fourth trophic level: trophic level: trophic level: trophic level: producers primary secondary tertiary consumers consumers consumers Heat Heat Heat Heat Decomposers (saprotrophs) Heat A food web at the edge of an eastern deciduous forest Figure 53-2 Page 1046 Pyramids of biomass Secondary consumers (1) Saprotrophs (10) Primary consumers (4) Producers (40,000) Tropical forest in Panama Primary consumers (21) Producers (4) Plankton in English Channel Pyramid of energy Tertiary consumers (21) Secondary consumers (383) Saprotrophs (5,060) Primary consumers (3,368) Producers (20,810) Notice that there is roughly a 90% reduction in energy with each consecutive trophic level A simplified diagram of the carbon cycle Air (CO2) 750 Animal Soil and plant microorganism Decomposition respiration respiration Photosynthesis by land plants 560 Combustion (human and natural) 6 Marine Partly decomposed plankton Soil remains Coal 1500 plant remains Natural gas Coal Oil Dissolved Erosion of CO in water 2 limestone to 38,000 form dissolved CO2 Burial and compaction to form rock (limestone) Carbon Cycle • Carbon dioxide is the pivitol molecule of the carbon cycle • Carbon is present as: • Carbon dioxide in the atmosphere • Carbon dioxide, carbonate, and bicarbonates in aquatic habitats • Carbonates in rocks such as limestone • Carbon fixation is done during photosynthesis by plants, protists, and photoautotrophic bacteria • Organic molecules are stored in plants, consumers, or as fossil fuels. • Combustion of fossil fuels releases carbon dioxide into the atmosphere • Cellular respiration releases carbon dioxide also • We’ll discuss human impact on global climate change later… A simplified diagram of the nitrogen cycle Atmospheric nitrogen (N2) Biological nitrogen Nitrogen fixation fixation (nitrogenfrom human activity fixing bacteria in 100 root nodules and soil) 140 Denitrification (denitrifying bacteria) ≤ 200 Decomposition (ammonification by ammonifying bacteria) Plant and animal proteins Internal cycling Assimilation (nitrification, assimilation, (nitrates, ammonia, or ammonification on land) ammonium absorbed by roots and 1200 Ammonia (NH3) used to make organic compounds) + and ammonium (NH4 ) Nitrification (Nitrifying bacteria) Nitrate (NO3–) Nitrogen Cycle • Bacteria can “fix nitrogen” which means they break apart nitrogen gas and convert it into ammonia or ammonium. • Decomposition also results in ammonia products and is called ammonification • Nitrification converts ammonia into nitrates and nitrites which can be used by plants to make organic compounds. • Denitrifying bacteria convert nitrates back into N2 Nodule Root nodules and nitrogen fixation A simplified diagram of the phosphorus cycle Phosphate rocks 10,000 (mineable) Geologic processes (e.g., uplift) Phosphate rocks Burial and compaction to form rock Phosphate mining Erosion of calcium Fertilizer containing phosphates phosphate minerals Excretion and Animals, crops decomposition Internal Dissolved cycling phosphates Internal 1000 90,000 cycling Marine 60 organisms Erosion Marine sediments Soil phosphates 9 4 x 10 200,000 Animal waste and decomposition Phosphorus Cycle • Has no gaseous component (from land to sediment and back to land only) • Erosion releases phosphate into the soil where it can be used by plants • It is returned to the soil via decomposers • Deposited in oceanic sediment – unavailable for years • Fertilizers, run off containing animal wastes, and sewage introduce it into aquatic ecosystems A simplified diagram of the hydrologic cycle Movement of moist air Condensation 40,000 Atmosphere (cloud formation) 13,000 Precipitation on land 111,000 Percolation through soil and porous rock Evaporation from ocean 425,000 71,000* Evaporation from soil, streams, rivers, and lakes Precipitation to ocean 385,000 Transpiration from vegetation Runoff to ocean 40,000 Ocean 1,350,000,000 Groundwater 15,300,000 Water Cycle • Let’s just review… Focus On 1 Page 1056 A hydrothermal vent community The fate of solar radiation that reaches Earth 30% reflected back into space immediately Figure 53-11 Page 1057 Less than one billionth of the sun’s total energy reaches Earth’s outer atmosphere. Less than 1% drives the winds and ocean currents 47% absorbed by the atmosphere 23% runs the hydrological cycle All solar energy is ultimately re-radiated to space as heat 0.02% captured by photosynthesis Seasonal changes in temperature Figure 53-12 Page 1058 Vernal equinox March 21 Summer solstice June 21 Winter solstice December 21 Circle of illumination Day Sun’s rays Night Earth’s orbit Sun Night Arctic Circle Day Autumnal equinox September 22 Atmospheric circulation Figure 53-13 Page 1059 Polar easterlies 60°N Westerlies 30°N Trade winds 0 Trade winds 30°S Westerlies 60°S Polar easterlies Geographic Ecosystems - Chapter 54 Biomes - large terrestrial regions characterized by similar climate, soil, and living things • Tundra • Taiga • Temperate Rain Forest • Temperate Deciduous Forest • • • • Grasslands Deserts Savanna Tropical Forests (dry and rain) Using precipitation and temperature to identify biomes Figure 54-1 Page 1066 Annual precipitation (cm) 400 Tropical rain forest 300 Temperate rain forest 200 Temperate deciduous forest 100 Taiga Temperate grassland, chaparral Tropical dry forest Savanna Desert Tundra 0 –10 0 10 Average temperature (°C) 20 30 ELEVATION ZONES High elevation LATITUDE ZONES North Pole Snow/ice Polar region Alpine tundra Subalpine coniferous forest Deciduous forest Low elevation Comparison of elevation and latitude zones Arctic tundra Taiga Temperate forest Mid-latitudes Average monthly Average monthly precipitation (cm) temperature (°C) Significance of precipitation in temperate biomes 28 24 20 16 12 8 4 0 –4 14 12 10 8 6 4 2 J F MAM J J AS OND J F MAM J J AS OND Month J F MAM J J AS OND Temperate deciduous forest (Nashville, Tennessee) Temperate grassland (Lawrence, Kansas) Temperate desert (Reno, Nevada) The world’s major biomes Equator Tundra Taiga Temperate deciduous forest and temperate coniferous forest (includes temperate rain forest) Temperate grassland Desert Chaparral Mountains with complex zonation Savanna Tropical dry forest Tropical rain forest Arctic tundra Tundra • • • • • • • Cold, boggy plains of the far north Seasonal snow melts Very little precipitation Nutrient-poor soil lies over permafrost Lichens, mosses, grasses, and sedges Rodents and hares; insects in the summer Migratory birds Figure 54-5 Page 1070 Taiga Taiga • An evergreen forest of the north • a.k.a. - boreal forest • Longer growing season, but little precipitation • Some deciduous trees; dominated by conifers • Yields much lumber and pulpwood Temperate rain forest Temperate Rain Forest • Cool weather, dense fog, high precipitation • NW US, SE Australia, southern South America • Dominated by conifers • Yields much lumber and pulpwood Temperate deciduous forest Temperate Deciduous Forest • Dense canopy of broad-leaf trees • Trees overlie saplings and shrubs • Great seasonal variation in temperature and moderate precipitation • Has been converted to agriculture in much of the world Temperate grassland Grasslands • Temperate areas with moderate precipitation • Dominated by grasses • Most native grasslands have been converted to agriculture; well-suited to raising cereal crops Chaparral Chaparral • Thicket of evergreen shrubs and small trees • California, Western Australia, Chile, South Africa, Mediterranean area • Dominated by drought-resistant shrubs and scrub and has adapted to fire Desert Deserts • Both temperate (cold deserts) and subtropical and tropical regions (warm deserts) • Low precipitation • sparse vegetation - small in size Savanna Savanna • Tropical grassland with scattered trees • Africa, South America, West India, and Northern Australia • Greatest abundance of hoofed mammals • Often converted to rangeland for domesticated animals Figure 54-12 Page 1074 Tropical rain forest Tropical Forests • • • • • • • • Tropical Dry Forests: Have both a wet and dry season Tropical Rain Forests: High temps and high precipitation Soils have little organic matter Unrivaled in plant and animal diversity Plant community is characterized by layers Biome is threatened by overpopulation of indigenous people and exploitation of resources by developed countries What do aquatic ecosystems all have in common? WATER!!! Water IS the habitat • What type of characteristics does water have? • High Sp. Heat, Surface Tension, Density… Aquatic Ecosystems: occupy most of Earth’s surface • Marine - salt water – Dominate Earth’s surface • Freshwater - include flowing-water, standingwater, and wetland ecosystems • Estuaries - occur where freshwater and saltwater meet Marine Ecosystems • 1. Intertidal zones - btwn land & ocean – Between low and high tides – Highly productive, but very stressful habitat • 2. Benthic environment - the ocean floor – Seagrasses, kelps, coral • 3. Neritic area - consists of shallow waters close to shore – Depths less than 200 m • 4. Oceanic provinces - comprises most of the ocean – Depths of over 200 m – Abyssal zone - benthic area from 4000-6000m – Hadal zone - benthic area deeper than 6000 m Classifying Aquatic Ecosystems • Aquatic ecosystems can be classified according to abiotic factors OR types of organisms • Types of Organisms: Benthos Periphyton Plankton Nekton Neuston • BENTHOS: – Bottom dwellers – Ex. Microbes, worms, clams, some crustaceans • PERIPHYTON: – Attach or cling to other structures – Ex. Aquatic plants, zebra mussels, Stentor • PLANKTON: – Microorganisms that float (phyto- or zoo-) • NEKTON: – Large swimming organisms (ex. Fish) • NEUSTON: – Live at the surface – Ex. Water striders, snails, other aquatic insects & larvae Estuaries • Where saltwater and freshwater meet • Organisms living here have adapted to being able to withstand constant changes in their environment (ex. salinity and temperature) Freshwater Ecosystems • Lotic - Rivers and Streams • Lentic - Lakes and Ponds • Wetlands - Bogs, Fens, Swamps, & Marshes LOTIC SYSTEMS • “Body of water in motion” • Ex. Rivers and Streams • Current is the most important feature – It is constant – And it shapes all features of the stream • Small Streams: • Headwater, typically cold, shallow, and fast-moving • Highly oxygenated • Depend on detritus as a primary energy input: allochthonous • Rivers: • Deeper, slower flowing, less dissolved oxygen ; autochthonous LENTIC SYSTEMS • Standing or still water contained within a basin • Ex. Lakes and ponds • The difference? • Lakes are deeper and have thermal stratification • Large Lakes are divided into the littoral, limnetic, and profundal zones Epilimnion 22-25 degrees Thermocline 10-20 degrees Hypolimnion 4-5 degrees Thermocline: Zone of rapid temperature change Turnover Organisms In Lakes • • • • • Controlled by many factors: Temperature Light Nutrient availability Oxygen availability • Affects many factors: • Nitrates, nitrites, ammonia, dissolved oxygen, turbidity, etc. WETLANDS • Defined by soil which is saturated with water for at least 6-9 months of the year • These are natural filters and are very important to the health of other habitats • 5 major types: • Marine - salt water • Estuarine - salt marshes & brackish wetlands • Lacustrine - associated with lakes • Riverine - associated with rivers, sometimes floodplains • Palustrine - the wetland IS the major feature Palustrine Wetlands • Major Non-Forested Wetlands –Marshes –Shrub-swamps –Peatlands : Bogs and Fens WETLANDS Wetlands are areas where The soil is saturated with water for a significant portion of the year. They serve as natural filters and are important in the health of other habitats. Wetlands • Wetlands can be freshwater OR saltwater, but in Michigan they are FRESH water • Where do they come from? • 1. From other wetlands • 2. From glaciers, river, or lakes. • There MUST be hydric soil. Major Palustrine Wetlands • 1. Marsh: a shallow basin of standing water with vegetation from shore to shore • Extremely productive habitat • Most dominant plant is the CATTAIL, but also has a lot of rushes, reeds, and other softstemmed plants. • Many are related to grasses. You can identify grasses by the unique characteristic of being hollow. • 2. Shrub-swamp - a wetland thicket dominated by 10-15 foot shrubs and young trees. • Often flooded areas • Interesting organism that lives here is the skunk cabbage. Why so interesting? • Many animals USE this habitat • 3. PEATLANDs made up the final type we’ll examine. A BOG and a FEN are classified as this Peatlands • 3a. Bog: has a floating mat of sphagnum moss (peat) and acidic water. • Plants get their nutrients from their surrounding habitats…not from the acidic water, which is nutrient poor • Plants must adapt to conserve water and some have adapted to become carnivorous • Ex. Leatherleaf, sundew, pitcher plants • Few animals actually LIVE here, but many visit and use this habitat • 3b. Fen: alkaline peatland • Has some sphagnum, but is not the dominant plant • Alkaline water • Many sedges, grasses, and small plants • Usually attached to flowing water • • • • Bog - acidic, stagnant Fen - alkaline, flowing Swamp - alkaline, flowing Marsh - neutral, stagnant Sand Dunes • What do sand dunes have to do with wetlands? Chapter 55 – Human Impact • • • • • • • • Let’s discuss: Pollution Overuse Overharvesting Destroying habitat Deforestation Global warming Ozone depletion Enhanced greenhouse effect Figure 55-12 Page 1101 Sunlight Atmosphere Much heat radiated from Earth is redirected back to Earth Only some of the heat radiated from Earth escapes to space Carbon dioxide Heat Heat Surface of Earth Ultraviolet radiation and the ozone layer Ultraviolet solar radiation Ozone Stratosphere Oxygen Troposphere Surface of Earth Surface of Earth Ozone present at normal levels Ozone present at reduced levels Ozone thinning Figure 55-15 Page 1105 Ozone (Dobson Units) 100 200 300 400 500 What can YOU do to help? • Conservation efforts: