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population structure • population ecology • population? • localized group of individuals of a single species population ecology chapter 14 • population density • dispersion pattern (population distribution) • clumped • random • uniform • dispersal? • decreased intraspecific competition • decreased relatedness of potential mates • mechanisms • abiotic • biotic • life tables • track survivorship • age intervals - survivorship • survivorship curves random clumped percentage of survivors (log scale) longevity uniform density and dispersion percentage of maximum life span • exponential growth model • growth occurs exponentially if no limiting factors • G=rN • logistic growth model • growth with limiting factors • carrying capacity (K) (K-N) • G=rN K • asymptotic • density-dependent factors • intraspecific competition • density-independent factors • seasonal factors • disturbance population size (N) population growth population size (N) population growth population size (N) time apr may jun jul aug month time population growth life history • boom / bust cycles • predator / prey population cycles • classic example • snowshoe hare / lynx • reproductive strategies • reproductive investment • tradeoffs • r-selection • K-selection • parental care snowshoe hare lynx sep oct nov dec human population • human population growth • balance between birth rate and death rates • carrying capacity? • fertilizer • 1909 - Haber process • population growth continues • age structure? • ecological footprint • to accommodate the expected population by 2025, food communities and ecosystems chapter 15 production must double community structure interspecific interactions • communities • assemblage of organisms • community ecology • study of interactions among organisms and abiotic factors and • interspecific interactions • interspecific competition • competition for resources by different species how these interactions affect communities interspecific interactions interspecific interactions • mutualism • each species benefits • commensalism • one benefits, other not harmed • Demodex interspecific interactions interspecific interactions • parasitism • ectoparasites, endoparasites • parasitism • nematodes, flatworms, etc. • parasitoidism • ex. mermithidae, Nematomorpha antipredator mechanisms antipredator mechanisms • predator avoidance • aposematic coloration • bright colors • predator avoidance • batesian mimicry - antipredator mechanisms antipredator mechanisms • predator avoidance • müllerian mimicry - each species model and mimic • predator avoidance • crypsis distasteful model / tasty mimic Dendrobates imitator Dendrobates imitator Dendrobates variabilis Dendrobates fantasticus Dendrobates imitator Dendrobates ventrimaculatus http://www.ucl.ac.uk/taxome/jim/Mim2/dendrobates.html antipredator mechanisms antipredator mechanisms • deimatic display • eyespots • deimatic display • eyespots • cephalopods antipredator mechanisms antipredator mechanisms • deimatic display • eyespots • cephalopods • spiders • rattlesnakes • deimatic display • eyespots • cephalopods • spiders • rattlesnakes antipredator mechanisms herbivory • deimatic display • eyespots • cephalopods • spiders • rattlesnakes • fruit fly? • responses to herbivory • Proteinase inhibitors • Herbivores detect proteinase interspecific interactions community dynamics • summary • trophic structure • food chains • producers • primary consumers • secondary consumers • tertiary consumers • quaternary consumers interaction competition mutualism parasitism herbivory predation commensalism inhibitors by taste • attraction of parasitoids • Caterpillar saliva --> volicitin • wasps lay their eggs in the caterpillars • allelopathy • secondary metabolites • eg. alkaloids effect on species 1 + + + + + effect on species 2 example + - virginia’s warbler / orangecrowned warbler ? armyworm / corn zooxanthellae flatworms, roundworms, athropod ectoparasites lynx / snowshoe hair quaternary consumers tertiary consumers secondary consumers primary consumers mites, pseudoscorpions producers community dynamics • trophic structure • food webs community dynamics • species diversity • species richness • relative abundance • consequences • pathogen transmission • diversity of other tertiary consumers secondary consumers secondary consumers primary consumers organisms primary consumers producers community dynamics community dynamics • disturbance • can be large scale or • secondary succession • soil already present • usual stages • annual plants • perennial herbaceous plants • shrubs • softwood trees (like pines) • hardwood trees small scale • succession • primary • initial colonizers in new areas • no soil • secondary • initial colonizers after disturbance pioneer community climax community community dynamics community dynamics • effects of invasive species • invasive fire ant (Solenopsis invicta) • keystone species • grizzly bears • anadromous fish (salmon) • beavers • prairie dog? ecosystem dynamics chemical cycling • ecosystem • energy flow • energy enters ecosystem through producers • primary production • general model for chemical cycling • abiotic reservoirs • producers extract chemicals from • • can be expressed as biomass ecosystems differ in biomass • flow of energy in food chain • represented as pyramid 10 kcal tertiary consumers 100 kcal secondary consumers • chemical cycling • constantly recycled 1000 kcal primary consumers abiotic reservoirs • decomposers return nutrients to abiotic reservoirs • local and global • scale is different for different nutrients consumers producers decomposers nutrients available to producers 10,000 kcal producers sunlight 1,000,000 kcal abiotic reservoirs carbon cycle phosphorus cycle • carbon dioxide cycles globally • combustion • phosphate cycling • no atmospheric component • very long term CO2 in atmosphere combustion photosynthesis aerobic respiration uplifting of rock weathering of rock higher level consumers producers phosphates in rock animals plants runoff primary consumers wood, fossil fuels detritus phosphates in solution animal bodies decomposers leaf litter rock phosphate sediment (precipitation) detritus ducers nitrogen cycle sustainability • nitrogen • most common gas in atmosphere • Soil conservation • mismanagement • fertilizer -- (N, P, K) -- different crops N2 in atmosphere plant have different requirements • crop rotation • irrigation animal denitrifying bacteria NO3- in soil detritus nitrogen-fixing bacteria bacteria nitrifying bacteria ammonifying bacteria NH4+ in soil phosphates in soil (inorganic) decomposers clearcutting • negative effects • erosion • loss of soil • loss of nutrients loss of habitat • • positive effects? conservation biology chapter 16 loss of biodiversity loss of biodiversity • major threats to biodiversity • habitat loss • invasive species • overharvesting • pollution • climate change • habitat loss • deforestation • urbanization • loss of wetlands invasive species • • fire ants • brown snake • overharvesting • overfishing • cod • sharks loss of biodiversity global warming • pollution • oil spills • biological magnification • PCBs • DDT • mercury • global climate change • warming • “greenhouse gases” - CO2, N2O, CH4 • trap radiation • 2012 - hottest year on record • phenotypic plasticity • effects on selection • range expansion problem high higher low
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