BIO 311D 2nd Edition Lecture 38 Outline of Last Lecture I Revisit Yellowstone wolves II Biotic interactions III In class exercise your example community Outline of Current Lecture I Community Dynamics Ecological Succession II Trophic Interactions and energy flow Current Lecture I Community Dynamics Ecological Succession A Parasitism one benefits other is harmed a How can host and parasite evolve by co evolution 4 21 b What s a good parasite One that doesn t kill its host so it could reproduce c Leeches attachment disks suck the blood of their host Has an anticoagulant in their saliva to prevent blood clotting from cutting off their blood supply from the host Humans could have receptors B Mutualism Tropical communities with high species diverse complex community interactions Mutualisms plant pollinator coral dinoflagellate a Which do you think affects the success of the organisms there more abiotic factors or community biotic interactions 1 Deserts and the artic major abiotic factors 2 Places with less severe climate changes tropics major biotic factors escaping from predator competition b Both organisms benefit from the interaction 1 Legume roots and nitrogen fixing bacteria turning N2 to ammonia NH3 2 Termites and symbiotic protists and bacteria that digest cellulose termites eat wood symbiotic microbes has the enzymes to digest the wood 3 Acacia trees and ants that defend them 4 Leaf cutter ants and fungi C For one case of mutualism tell how it evolved by mutualism a For example most flowering plants have adaptations such as nectar or fruit that attract animals that function in pollination or seed dispersal In turn many animals have adaptations that help them find and consume nectar D What happens to a population when its mutualistic partner goes extinct a Population may decrease in size May lose its ability to survive E Temporal Changes in communities a Ecological succession progressive changes in species composition over time b Early Colonist species pioneers change conditions for later arriving species c Primary succession on bare rock soil develops gradually d Secondary succession after disturbance forest grows back after clearing or after a fire e Some ecosystems are maintained by pericarp fires This is an example of intermediate disturbance community held at intermediate stage of succession f Succession of decomposers on a dead body CSI succession g Succession in your mouth Bacteria on teeth dental plaque community 1 Clean surface sugar protein deposits 2 Primary colonizes Streptococcus lock onto surface coatings 3 After 1 3 days new species accumulate biofilm growth on dextran polymer 4 After 1 week new bacteria species grow h Which of the following is true of primary succession but NOT secondary succession 1 Initial species change habitat to facilitate the success of later species True for both 2 Succession begins on bare rock II Trophic Interactions and energy flow A Ecosystem biotic and abiotic components The organisms in a particular area and the physical environment with which they interact constitute an ecosystem a Energy flows through ecosystems b Nutrients cycle within ecosystems B Primary producers trap sunlight What s the general equation for photosynthesis a The annual productivity of an area is determined primarily by temperature and moisture C What ecosystems have the greatest productivity per area a Primary productivity is most often limited by what two factors Temperature and water D Energy distribution in one link of the food chain How much of the plant mass consumed by the caterpillar becomes new caterpillar mass growth a 2nd law of thermodynamics because of entropy there is a progressive loss of useful energy along the food chain b At each step of the food chain there is a loss of usable energy for biomass production based on 10 trophic efficiency
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