Example exam questions Note Last 4 slides on ppt for last Monday will be covered in global change lecture on Nov 3 1 http ib berkeley edu courses bio1b Alfred North Whitehead told us to seek simplicity and A mistrust it B embrace it C further simplify it D use it to forecast ecological change E complicate it 2 The earth s major terrestrial biomes as characterized by their dominant vegetation are most clearly separated by In ecological experiments replicates are NOT Exam questions for my section will be based on LECTURE material not text except where I ve used text figures or tables in lecture 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 changes over space and time that we did not manipulate A B C D E 3 pH and temperature Precipitation and nutrient availability salinity and oxygen concentration Temperature and precipitation Nutrient availability and soil pH 4 Rain shadows and Mediterranean climates e g California if the land is warmer than the ocean moisture in marine air is not dropped until adiabatic cooling over mountains summer drought If land cooler than ocean moisture is dropped winter rains Habitats resources conditions and niches Rain shadow Eastern Sierra 5 6 Water ends up in lakes rivers or ground water Adiabatic changes in temperature occur due to changes in pressure of a gas and not from any heat exchange The dew point is the temperature to which a given parcel of air must be cooled at constant barometric pressure for water vapor to condense into water Adiabatic cooling occurs in the Earth s atmosphere when air rises This can cause cloud formation or precipitation if the air is cooled below the dew point Adiabatic heating occurs in the Earth s atmosphere when an air mass descends Rain forest Alpine lakes Desert Rain shadow Eastern Sierra 7 8 Water ends up in lakes rivers or ground water Seasonal mixing regimes water is densest at 4oC winter and summer stratification spring and fall overturn Thermocline stratum of rapid temperature change Can separate oxygenated from hypoxic habitat Lakes that experience seasonal freezing Mixing replenishes nutrients for algae in photic zone 9 Eutrophic river lake estuary nutrient rich likely to produce noxious or harmful algal blooms cyanobacteria toxic dinoflagellates Mesotrophic intermediate nutrient concentrations Oligotrophic low nutrient concentrations very clear water good water quality for humans and fish 10 River networks Downstream concentrative fluxes of water sediment solutes detritus and passive organisms Upstream and upslope dispersive backflows of mobile organisms Systematic downstream increases in discharge solar radiation and changes in sediment size habitat structure and disturbance regimes Confluence nodes pulses of enrichment adjacency of contrasting habitats refuges David Schindler s experimental lakes Easier for wind to stir nutrients in shallow basin making such lakes vulnerable to eutrophication 11 12 Energy carbon sources change downstream Terrestrial detrital carbon e g dead leaves that fall into streams Attached algae Fine particulate detritus and phytoplankton 13 Camille McNeely downstream changes in energy sources to grazers 14 Detritus dead organic matter Cover down drainage networks Headwaters woody debris forest cover A 5 km2 Meandering middle reaches clean gravel beds hyporheic under the stream bed habitat undercut rooted bank vegetation off river habitat 15 Estuary where rivers empty into oceans fresh water 0 salt meets salt water 3 salt tidal prisms with heavier salty water underneath Lowland floodplain rivers floodplain marshes or forests off channel water bodies 16 Vertical and onshore offshore zonation Important nurseries for offshore fisheries Tidal prism wedge of fresh water overlies denser salt water 17 18 Intertidal vertical zonation Neritic nearshore subtidal Plankton passive drifters Nekton active swimmers Benthos life on substrate or bed of sea lake spring or rivers and streams Benthic infauna 19 zooplankton phytoplankton 20 Resources conditions and the fundamental niche Pelagic Offshore beyond Continental Shelf What determines the distribution and abundance of species In part their tolerance of conditions and their need for certain resources condition abiotic environmental factor that varies in space and time and affects the performance of organism 21 Structure Cover Food 22 Macan s filter continued Macan s filter similar to Fig 50 5 p 1056 Campbell If a species is absent from a habitat is it because of 1 Dispersal Yes hasn t arrived yet barriers insufficient time No propagules have arrived but don t persist propagule a dispersing unit capable of establishing a new population e g one asexual spore Adam and Eve a pregnant female fish or a fragment of a plant that can reproduce vegetatively 2 Behavior Yes colonists avoid habitat No colonists select habitat but don t persist resource all things consumed used up by organisms space nutrients water prey holes for refuge etc 23 3 Abiotic factors Yes temperature salinity pH moisture conditions etc are outside the range that the species can tolerate No abiotic conditions are tolerable 4 Biotic interactions Yes species is excluded by predators pathogens competitors or the lack of prey resources or mutualists No 24 Example Africanized bees may have been selected in tropics to withstand or avoid predation by army ants aggressive defensive stinging bees disperse at small colony size Fig 50 6 p 1084 Campbell 7 50 5 p 1056 Campbell 6 European bees shiver to warm hives during winter Will second trait limit the northward spread of Africanized bees Don t build up large enough colonies to 26 warm hive by collective shivering 25 Performance is generally nonlinear across a range of intensities of an abiotic condition some is good more is better even more is very bad A resource can become a condition at high or low levels e g light Water Performance of species Distributions of organisms determined by cooccurrence of a number of critical potentially limiting resources and conditions Reproduction Interactive Non interactive Growth grows Nitrogen s cold g r r g s hot Condition e g temperature Survival dies dies 27 Niche Range of conditions resource levels and densities of other species within which an organism or species can survive and reproduce persist over time An N dimensional
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