8OrganelleSacs or their compartments that separate different activities inside the dellOrganelleMoleculesatomsSubatomic Particles
9Cell(smallest living unit) May live independently or part of a multicellular organismCellOrganelleMoleculesatomsSubatomic Particles
10TissueA group of cells and surrounding substances functioning together in a specialized activity.TissueCellOrganelleMoleculesAtomsSubatomic Particles
11Organ A group of tissues working together to perform a common task. CellOrganelleMoleculesAtomsSubatomic Particles
12Organ systemTwo or more organs interacting to contribute to the survival of the whole organism.Organ SystemOrganTissueCellOrganelleMoleculesAtomsSubatomic Particles
13multicellular organism An individual composed of specialized interdependent cells arrayed in tissues, organs, and often organ systemsMulticellular OrganismOrgan SystemOrganTissueCellOrganelleMoleculesAtomsSubatomic Particles
14Multicellular Organism Population:Subatomic ParticlesAtomsMoleculesOrganelleTissueOrganOrgan SystemMulticellular OrganismCellPopulationA group of individuals of the…
15Multicellular Organism CommunitySubatomic ParticlesAtomsMoleculesOrganelleTissueOrganOrgan SystemMulticellular OrganismCellPopulationCommunity= a group of organisms of different species (i.e. many populations)….
16Multicellular Organism Organ SystemMulticellular OrganismSubatomic ParticlesAtomsMoleculesOrganelleTissueOrganCellPopulationCommunityEcosystemEcosystemAll biotic and abiotic components of a certain area
17Multicellular Organism BiomeBiomeOrgan SystemMulticellular OrganismSubatomic ParticlesAtomsMoleculesOrganelleTissueOrganCellPopulationCommunityEcosystemMajor types of ecosystems on earth, occupying large geographic regions
18Multicellular Organism BiosphereOrgan SystemMulticellular OrganismSubatomic ParticlesAtomsMoleculesOrganelleTissueOrganCellPopulationCommunityEcosystemBiomeBiosphereThose regions of the earth’s waters, crust and atmosphere in which organism can exist.
21Factors affecting distribution of organisms (biogeography) Dispersal limitationsNot all areas are accessible – geographic isolationHabitat selectionAnimalsBiotic FactorsAbiotic Factors
223. Biotic FactorsAbsence of symbiosesLack of pollinatorsCompetition
23CompetitionWhenever the quantity of useful matter or energy falls below the level needed for the maximal growth of two or more organisms which must draw on the same supply, a contest begins.Competition from introduced species can shrink an organism’s actual range
34Locations of the earth’s biomes due to: .One biome type may occur in different areas of the worldDifferent plant species but same:Physiognomic structure –Similarities due to convergent evolution – similar phenotypes due to similar selection pressures over timeSimilar climate, soils, disturbance patterns,…
55Characteristics of Populations Dispersion –Size –Density - the number of individuals living in a specified area
561. Dispersion Patterns of Dispersion: Clumped – Uniform – evenly spaced due to:Competition for resourcesAllelopathy –Random – unpredictable; position of one individual cannot be predicted from position of another.
602. Population SizeDemography = study of factors that affect the growth & decline of populationsLife Histories = events from birth through reproduction to deathTrade-offs between investments in reproduction & survival when there are limited resources
62Controls at every stage of life history deathreproductionHerbivory, disease, competition, drought, flood, freezemature plantgrowthseedlingSeed rain from mature plantsSeeds washed away, eaten, decomposedDormancy (seed bank)
63DemographyChange in Population size = (B + I) – (D + E)
64Exponential Growthoccurs when resources are abundant or when an important constraint has be removed.Ex.
733. Density-Dependent Control of Population Size When population density is low, a population grows rapidly.When density is high, populations may grow slowly, remain stabile (zero growth) or decline – why?.High density puts plants at greater risk of …..
74Density-Independent Control of Population Size = events that cause more deaths or fewer births regardless of population densityExamples?
75Plants have developed adaptations to population density At low density, population is limited only by intrinsic rate of growth (r)At high density, population is limited by carrying capacity (K)R selection and K selection
84What factors determine the plant species composition & the relative of abundance of different species in a community?Biotic & abiotic components of the habitat
85Abiotic components of habitat & their effect on community structure: Each species has a tolerance range –Climate – temp, moistureSoil – types, pHLatitude & altitudeDisturbance
86Disturbance= decrease or total elimination of the biotic components of the habitatResults: decrease in biomass, diversityNatural events –Human-caused –Frees resources, creating opportunities for new species, different compositionAll communities have evolved with some type of disturbance, varying in type, frequency, & severity
87Small-scale, frequent disturbance Ex. Trees downed in wind stormCan prevent large-scale disturbance – fire!Ex. Yellowstone fire of 1988Fire suppression in fire-dependent ecosystem caused massive, stand-replacing fire
90Human - caused disturbance + introduced species = disaster Ex. Cheatgrass – wildfire cycleOvergrazing in ecosystem that did not evolve with large herbivoresCheatgrass introductionDecrease in fire frequency (100 yr to 5 year cycle)Conversion of ecosystem with tremendous loss of diversityThese types of problems creating mass extinction worldwide
97Biotic components of habitat & their effect on community structure The plant itselfBenefit ex: beech/oak forest creates shade needed for other young beech & oak to growDetriment ex: pine forest creates shade but pines need lots of light to grow (succession)
982. Other plant speciesTheory of competitive exclusion: when two species compete for the same limiting resource (occupy the same niche), the species that is less adapted will be excluded from the community by the superior competitor
99One will become extinct or evolve to use a slightly different set of resources Species BSpecies ASpecies AbundanceADBClowhighLight intensity
101If this theory is true, then actually very little competition in nature, because each plant occupies a niche.Niche=Includes all aspects of a species’ use of biotic & abiotic resources (microclimate, rooting zone, pollinators, etc)
1023. Other (non-plant species) Interactions with animals, insects, fungi, bacteriaMutualism –Ex.Ex. Pollinator gets nectar and plant gets pollen transferEx. Animals eat fruit (nutrition) and seeds are dispersedEx. Acacia trees get defense from herbivores & ants get home, food
104Commensalism – one species benefits & other is not affected Competition –Predation – one harmed, other benefitsHerbivorypathogens
105Controls on community structure Dominant species = species with the highest abundance or biomass in the communityControls occurrence & distribution of other speciesIf eliminated, other species take overEx. Douglas fir
106Keystone speciesEx. Sea otter – reduction in populations caused boom in sea urchin population, destroying kelp forests (drastic decline in diversity)
108Succession=Species replacement continues until the composition of species becomes relatively steady under prevailing climatic conditions & disturbance regimes (dynamic equilibrium, not climax).
109Two major types of succession Primary SuccessionSecondary Succession
1101. Primary succession Sequence: . As these decay, acids weather the rock & primitive soil formsPioneer plants establish (r-selected)Pioneers replaced by K-selected species
111The Nature of Pioneer Species typically small plants, short life cycles, producing an abundance of small seeds which are quickly dispersed (wind & water)can grow in N-poor soil because of their mutualistic interactions with nitrogen-fixing bacteria.
118Spruce enter forest and replace alders/cottonwoods
119Hemlock slowly replace Spruce. Hemlock is “climax”
120What Pioneers Do: Facilitation accumulation of their wastes and remains adds volume to the soil and enriches it with nutrients that allow other species to take hold.
1212. Secondary SuccessionPlant community is destroyed but soil remains/ new soil exposedExamples?Typical progression: small herbs & grasses shrubs trees
122Pioneer speciesSometimes these opportunistic species (especially invasive weeds!) inhibit the growth of the native climax species changing the structure and type of climax community forever.Ex. cheatgrass
1283. Species compositionDetermined by soil resources, climate tolerance ranges, stresses (ex. Competitive interactions, herbivory)
1294. Trophic levels = Feeding levels Autotrophs First level of all food webs---- primary producersHeterotrophs – consumers - depend directly or indirectly on energy stored in tissues of primary producers.
130Types of Heterotrophs Herbivores Parasites Detritivores Carnivores – eat herbivores & other carnivores – secondary consumersOmnivores partake of a variety of ediblesDecomposers - extract energy and recycle nutrients from organic matter.
131Decomposition links all trophic levels Fig 54.2
132Some organisms like man extract energy from more than one trophic level so it is hard to assign them to a specific trophic level.Actual feeding relationships in an ecosystem are complex –.