1Example exam questionsNote: Last 4 slides on ppt for last Monday will be covered inglobal change lecture on Nov. 3.2Exam questions for my section willbe based on LECTURE material, nottext except where I’ve used textfigures or tables in lecture.• http://ib.berkeley.ed u / c ourses/bio1b• Alfred North Whitehead told us toseek simplicity and– A. mistrust it– B. embrace it– C. further simplify it– D. use it to forecast ecological change– E. complicate it3• In ecological experiments, replicates are NOT– A. separate (independent) units of study– B. treated as identically as possible by ecologists– C. used to assess variability that arises from factors we didn’t manipulate– D. unmanipulated units used to assess how results are affected by changesover space and time that we did not manipulate4• The earth’s major terrestrial biomes (ascharacterized by their dominant vegetation) aremost clearly separated by– A. pH and temperature– B. Precipitation and nutrient availability– C. salinity and oxygen concentration– D. Temperature and precipitation– E. Nutrient availability and soil pH5Habitats, resources,conditions, and niches6Rain shadows and Mediterranean climates (e.g. California): ifthe land is warmer than the ocean, moisture in marine air isnot dropped until adiabatic cooling over mountains) !summer droughtIf land cooler than ocean, moisture is dropped ! winter rainsRain shadowEastern SierraWater ends up in lakes, rivers, or ground water…7• Adiabatic changes in temperature occur dueto changes in pressure of a gas, and notfrom any heat exchange.• The dew point is the temperature to which agiven parcel of air must be cooled, atconstant barometric pressure, for watervapor to condense into water.• Adiabatic cooling occurs in the Earth'satmosphere when air rises. This can causecloud formation or precipitation if the air iscooled below the dew point.• Adiabatic heating occurs in the Earth'satmosphere when an air mass descends.8Rain shadowEastern SierraWater ends up in lakes, rivers, or ground water…Rain forest Alpine lakes Desert9Lakes that experience seasonal freezing…10Seasonal mixing regimes: water is densest at 4oC ! winterand summer stratification, spring and fall overturn.Thermocline = stratum of rapid temperature change. Canseparate oxygenated from hypoxic habitat.Mixingreplenishesnutrientsfor algae inphotic zone11Eutrophic (river, lake estuary): nutrient rich, likely toproduce noxious or harmful algal blooms (cyanobacteria, toxicdinoflagellates)Mesotrophic – intermediate nutrient concentrationsOligotrophic – low nutrient concentrations, very clear water(“good” water quality for humans and fish)Easier for wind tostir nutrients inshallow basin,making such lakesvulnerable toeutrophicationDavid Schindler’s experimental lakes12River networks• Downstream (concentrative)fluxes of water, sediment, solutes,detritus, and passive organisms• Upstream and upslope (dispersive)backflows of mobile organisms• Systematic downstream increasesin discharge, solar radiation, andchanges in sediment size, habitatstructure, and disturbanceregimes• Confluence nodes– pulses of enrichment– adjacency of contrastinghabitats (refuges)1314Terrestrialdetrital carbon,e.g. dead leavesthat fall intostreamsAttachedalgaeFine particulatedetritus* andphytoplanktonDetritus = dead organic matterEnergy(carbon)sources changedownstream15Camille McNeely, downstreamchanges in energy sources to grazers16Cover down drainage networks• Headwaters:– woody debris– forest cover• Meandering middle reaches– clean gravel beds; hyporheic(under the stream bed)habitat– undercut rooted bankvegetation– off river habitat• Lowland floodplain rivers– floodplain marshes or forests– off channel water bodiesA < 5 km217Estuary: whererivers empty intooceans, fresh water(0 % salt) meetssalt water (3 %salt): tidal prismswith heavier saltywater underneathImportant nurseries foroffshore fisheriesTidal prism—wedge offresh water overlies densersalt water18Vertical and onshore-offshorezonation19Intertidal vertical zonation20Neritic: nearshore subtidalBenthos: life on substrate orbed of sea, lake, spring, orrivers and streamsPlankton: passive driftersNekton: active swimmerszooplanktonphytoplanktonBenthic infauna21PelagicOffshore, beyondContinental ShelfStructure? Cover? Food?22Resources, conditions, andthe fundamental niche• What determines the distribution andabundance of species?– In part, their tolerance of conditions,and their need for certain resources*condition: abiotic environmental factor thatvaries in space and time and affects theperformance of organism**resource: all things consumed (used up) byorganisms (space, nutrients, water, prey, holesfor refuge, etc)23Macan’s filter (similar to Fig. 50.5, p. 1056 Campbell):If a species is absent from a habitat, is it because of:1. DispersalYes: hasn’t arrived yet (barriers, insufficient time)No: propagules* have arrived, but don’t persist*propagule: a dispersing unit capable ofestablishing a new population (e.g., one asexualspore, Adam and Eve, a pregnant female fish,or a fragment of a plant that can reproducevegetatively)2. BehaviorYes: colonists avoid habitatNo: colonists select habitat, but don’t persist24Macan’s filter, continued3. Abiotic factors?Yes: temperature, salinity, pH, moisture conditions*etc. are outside the range that the species cantolerateNo: abiotic conditions are tolerable.4. Biotic interactions?Yes: species is excluded by predators, pathogens,competitors, or the lack of prey resources** ormutualistsNo: ?25Fig. 50.6, p. 1084 Campbell 750.5, p. 1056 Campbell 626Example: Africanized bees may havebeen selected in tropics to withstand oravoid predation by army ants--aggressive defensive stinging--bees disperse at small colony sizeEuropean bees shiver to warm hives duringwinter. Will second trait limit thenorthward spread of Africanized bees?(Don’t build up large enough colonies towarm hive by collective shivering.)27Performance is generally nonlinear across a range of intensities of anabiotic condition: some is good, more is better, even more is very bad …Condition (e.g., temperature)coldhotPerformance ofspeciesReproductionGrowthSurvivalssggr r28A resource can become a condition at highor low levels, e.g., light. Water.Distributions of organisms determined by co-occurrence of a number of critical (potentiallylimiting) resources and
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