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BIO120H rough test 2 notes

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University of Toronto St. George
Kenneth Bartlett

Lecture 9-10 ● sink patch has a net flow into it ● big patch is the source path where all the organisms are. This would be the net producer. ● stepping stone patch --> even if it's small it causes extra migration because species jump large patches through stepping stone patches. ● example for this is Pikas--> basically they live on high mountains and make hay piles to get through winter. in this example, they move to patches of mining where they threw out drugged rocks and pika lived on these. ● This migration, subpopulations of species can go to extinction by ● density dependence ● allele effect at low densities ● predator prey ● unstable competition contoured by ● migration to rescue ● habitat patchiness ● non-equal conditions ------------------------------------------------------------------------------------------------------------------------ ● 2 hypothesis ● 1 )frederick clements organismal/holistic hypothesis ● typological community concept ● necessary of biology is why certain species are found together ● 2) Henri gleeson ● individual hypothesis ● each species is independent of each other ● coincident of environmental selection ● Robert whittaker ● tested the hypothesis by going to mountains where gradients are found he studied tree species and checked elevation. ● Robert proved gleeson was the correct one by D graph being correct ● graph A was clemson (look at this on notes and also look at the names bold names) ● Curtis also proved Gleeson by multivariate statistics ● Margaret proved trees migrate independently --> gleeson wins ● basically there is continuous variation in environments not discrete ---------------------------------------------------------------------------------------------------- ● pioneers go from place to place/ they are outcompeted by k species ● primary succession is the first species to arrive, for say after volcano ● farm in forest --> disturbance ● if habited--> secondary succession ● Stage 1 ● organic material blends with inorganic after a volcano = pioneers ● eventually turns to a habitat from plant --> animal -->other animals ● All happens spontaneously ● starts with weedy r strategists ● ends at climax stage = equilibrium no change ● pioneers annual weeds ● stage 2 ● perennial weeds ● Seeds don't germinate if lack of sunlight bigger plants out compete by blocking sun ● Stage 3 ● woody shrubs moves in ● Stage 4 ● tree saplings--> a lot of shade --> kills early successors ● stage 5 ● bigger trees --> kills shrubs too and ground starts to clear out and activity happens mostly on top level ● stage 6 ● shade tolerant species form on bottom ------------------------------------------------------------------------------------------------------------------- ● tropical rain forests ● secondary succession happens by tree knocking over bunch of other trees ● fire dominated communities ● bottom catches on fire --> trees are fine but if catches on pines on top then its bad ● heat causes pine vine to open and let out seeds so only when its hot ● they slowly let out seeds over time when fire starts and these will be the new secondary successors ● no shade species in fire communities ------------------------------------------------------------------------------------------------------------------------- ● CHAPTER 14 summary ● · Biological community is populations interacting. ● · Characterize communities by # of species, organization, food webs. ● · Maybe separated by abrupt transitions (ecotones), closed community ● · Open community is independently distributed. ● · Ecotones may be because of difference of soils etc. doesn’t happen where there’s gradual change of environment ● · Species along an environmental gradient is a “continuum concept” ● · Gradient analysis à species plotted on gradient of environmental conditions à for open communities ● · # of species or species richness (different species) is simple measure of community. Within species à trophic levels à similar ways of life and food sources ● · Keystone remover eat whatever thereby influence community structure ● · Species influence on community à 1) connectedness webs = feeding 2) energy flow webs between consumer and resource 3) functional webs = influence of species on other specie populations ● · Community response to environment à 1) constancy = ability to resist change \ resilience = ability to return to original state. ● · Humans affect community composition/structure. ● · Can change from one state to another ● · Consumers depress size of tropic levels below, indirectly increase 2 levels below (top down control) ● · Bottom effects top (bottom up control) ● · Trophic cascade à indirect effects consumer-resource goes through 4+ trophic levels ● CHAPTER 15 summary ● · Climax community = ultimate association of plants and animals ● · Sequence of communities at a given point = sere ● · Curtis and Mcintosh à continuum concept of the climax ● · Joseph Connell R.O Slatyer succession processes à facilitation, inhibition and tolerance. ● · Facilitation àFirst successions makes it easier for next ones ● · Inhibition à species in sere make conditions less favorable for others to come in as well. ● · Tolerance à species establishment is independent of other species, but not environmental conditions. ● · Pioneering species have many small seeds, easily dispersed. Shade intolerant grows fast, late stage species have opposite. ● · Good colonizers = first stage, late stage = good competitors ● · Transient climaxes develop on ephemeral resources and habitats. ● · Regional climax à transient successional sequences ● · Cyclic climaxes are driven by harsh conditions, such as winds, frost. ------------------------------------------------------------------------------------------------------------------------ ● lecture 11 ● Primary producers are plants getting energy from sun. ● Primary consumers are herbivores, basically plant eaters à primary consumer or secondary producer ● Then carnivores eat herbivores. ● Detritivores = eat dead organic matter bacteria etc ● Beetles eat golden rods and they die, but the other golden rods are insecticide treatment and they’re doing fine and they’re out competing the other plants “control group”. Beetles are the secondary consumer. ● Herbivores not limiting plant growth ● The three paper conceptual journal, 1960 “trophic cascades” ● Sands ● Carnivores keep the herbivores and keep them regulated. This is an indirect effect of the carnivores. ● Indirect effect à trophic cascades ● Plants à beetles à spider or Anolis ● Anolis eats spiders too ● Fish eats larval dragonfly ● Dragonfly eat pollinator ● So basically fish help pollinator ● •  Direct and indirect effects can be opposed ● •  Indirect effects can be as strong as direct ● •  Keystone consumers can shift ● communities between alternative states ● Outcomes not fundamentally predictable, ● depend on interaction strengths ● Experiments needed, perhaps long-term ● ● ● Special difficulties of herbivory ● •  Easy to be a carnivore: Animal tissues ● easy to convert into animal tissues ● •  Plant tissues hard to convert into animal ● tissues ●  Cellulose and lignin tough, indigestible without ● microbial symbionts ●  Plant tissues heavily defended against ● herbivores, mechanically and chemically ● Coevolutionary race between plants and ● insect herbivores is responsible for much of ● biodiversity: specialization is common ● selection on plants having defense structural etc ● selection on herbivores mouths that go around structural defenses and resistant to the plants toxicity ● Milkweeds excrete white sap and repellent latex under pressure in leaf veins. It’s defense and it’s poisonous, toxic, ● Caterpillars don’t detoxify the poison, but ● sequester it in their cuticle, making themselves ● poisonous and distasteful ● Caterpillar eats the leaf but moves poison in outside of skin, so they’re fine ● Plants are upright stands out for birds it says I’m poisonous ● There are specialist herbivores that can get by toxic defense ● ● Chemicals deter generalist herbivores ● Cocaine ● Adrenaline ● Morphine ● Plants made these chemicals for defense ● Cow eats A LOT so generalist ● Grasshopper only needs to eat like once so picky ● Grinding teeth on cows, eat chews for long time because cellulose are hard to break and 4 stomachs and it’s once and just does chemistry next, regurgitates to eat twice. ------------------------------------------------------------------------------------------------------------------------ ● lecture 12 ● That second goal is to demonstrate the way that an actual scientific investigation gets started—with a question—and then moves along through a process in which data are brought to bear. ● primary seed dispersal of glacier lily doesn't get very far. ● they have elaiosome structure provides ants they pick them up and eat these and seeds come with the ants and they toss them off, so its being dispersed by ants which is the only dispersal. ● success of a seed is if it survives till next spring ● rockness is measured by tool built (stick) and stick into ground ● golfer that digs leaves dirt on entrance of tunnel usually but in winter they can’t do that. ● tunnels in snow → take dirt and pack it in tunnel in snow ● then you can measure the length of these trails ● lilies are where there are rocks because golfers can't go through soil so they survive. ● seeds still are where the soil moisture is good. but it doesn’t seem like it visually because golfers eat them. ● desiccation → seeds away from rocks ● usually pressure for plants to disperse away from parents ● Cantor & Whitham same experiment with golfers they did but experiments and went further ● polar bear down, grizzly bear north and they meet so extinct but genome mates ------------------------------------------------------------------------------------------------------------------------ ● Chapter 16.0 Biodiversity ● · the numbers of species in most groups of organisms—plant, animal, and perhaps microbial—increase markedly toward the equator ● · diversity increases without limit over time, barring catastrophes such as meteorite impacts that cause mass extinctions of species. ● · Tropics older than rest so most diverse ● · Second theory says that diversity reaches an equilibrium, new specie, specie going instinct. ● · geographic factors also affect species richness. ● · the niche relationships of species provide an informative measure of community structure. ● · The more overlap the more species compete in niches ● · Species must be at carrying capacity (equilibrium) to be crowded and to coexist in same niche, if not it won’t be necessary. ● · Nonflying mammals are no more diverse at equator than temperate regions ● · Temperature difference so epiphytes go to tropic, and herbivorous insects go to tropics because more plant food ● · Morphology as an indicator of ecological role ● · Average niche breadth remains the same in communities with diff # of species ● · ecies diversity increases as a stream becomes larger and presents more kinds of habitats and a greater variety and
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