Transcript Ecology
Ecology The study of Interactions Ecology • Interactions between organisms and their biotic and abiotic environments. – Biotic = other organisms & their products. • Intraspecific (among same species) • Interspecific (among different species) – Abiotic = non-living environment • Climate, Mineral Soil, Atmosphere, Temperature, Humidity, etc. • BIG questions – involving lots of factors. – Difficult Research! Ecology Broken down into sub-disciplines: 1. Organismal Ecology – how individual organisms work within their environments. – Physiological Ecology • Energy allocation, reproduction – Evolutionary Ecology • Adaptations to environments – Behavioral Ecology • How organisms act to accomplish certain goals. Ecology 2. Population Ecology – Study of groups of organisms of the same species, usually living in a particular area = populations! – Often involves #’s • • • Population increase/decrease Fecundity (reproductive capacity) Factors influencing population size – Food, shelter, predation, etc. Ecology 3. Community Ecology – Study of all organisms of all species occupying a particular area. • – – – – – – Usually, assemblages of species are typically studied (easier to deal with). Predation Competition Disturbance Succession Community Structure Energetics Ecology 4. Ecosystems (“Systems Ecology”) – Community of organisms plus all abiotic factors. – Emphasis on energy flow & nutrient flow • • Energy – unidirectional Nutrients – cyclic – Lake – Pond – Patch of forest of a specific type. Ecology 5. Landscape Ecology – Interactivity between different ecosystems. – “Edge Effects” – Biogeography • Distributions of organisms. – Clumped, Random, Uniform, etc. • Dispersal, range. Ecology 6. Biosphere (“Global Ecology) – Largest area – how landscapes interact. – Global nutrient cycling – Ozone, Greenhouse gasses, etc. Ecological Systems are Complex! Organism Population Community Ecosystem Landscape Biosphere Organismal Ecology • Genetic influences – Response to stimulus, Taxis, Tropism, Migration. – Signals & Communication. – Mating & Parental Behaviors. – Social interactions. • Environmental influences. – Learning, Association, Cognition. Interactions among Populations • Intraspecific (same species) • Population Size – Births/Immigration – Deaths/Emmigration – Growth • Births/Immigration > Death/Emmigration – Growth Rate (“Rate of Increase”) • Changes in Growth over time • Density = numbers/area Interactions among Populations • Exponential Growth ∆N ∆t But… • Carrying Capacity – Available resources limit population size Interactions among Populations • Dispersion = spacial distribution – Clumped – Uniform – Random Interactions among Populations • Life History Differences – How specific organisms live their lives • Survivorship Curves – Type I – large mammals, ↑ parental care. – Type III – plants, fish, ↓ parental care. – Type II – many in between. Interactions within Communities • Competition • Predation – Herbivory • Parasitism – Disease • Mutualism • Commensalism Competition -/- • Exploitive – indirect usually, typically negativelyeffecting species. – Light, water, “limiting resources” – limit population size. • Adaptations allow better (or poorer) resource exploitation (speed, root efficiency, etc.) • Competitive Exclusion • Resource Partitioning – to avoid competition. • Ecological Niche – Total of an organism’s use of biotic & abiotic resources – where it “fits” in the environment…sort of. Predation +/- • Feeding! -- One species benefits at the expense of another species. • Leads to many adaptations: – Cryptic coloration (Camouflage) • For both predator & prey! – Aposematic coloration (Warning) – Mimicry (of unpalatable species) • (Herbivory) – a type of predation in which the prey is not killed, but is still at a disadvantage! – Aposematic & Mimicry in plants! – Chemical, Mechanical, & Symbiotic defenses. Parasitism +/- • One species compromises another living host while living on or in it. • Feeding, protection, reproduction • Complex lifecycles • Endoparasites, Ectoparasites Misteltoe • Disease – sometimes. – “Pathogens” = disease-causing agents Mutualism • “Symbiosis” between two organisms. • Both Benefit! • Clownfish/Anemone, Ant/Acacia, Legume/Rhizobium. +/+ Commensalism +/o • One species benefits, the other is neutral. • Algae on shells & fish, Cattle Egrets, Insects following leafcutters/army ants. Changes in Communities over TIME • Succession: progressive changes in community structure over time. – Primary Succession – from bare rock. – Secondary Succession – from some intermediate state. • Disturbance – not always bad – “Intermediate Disturbance Hypothesis” Trophic Structure of Communities • Food Pyramids • Food Webs • Producers • 1o consumers – (herbivores) • 2o consumers • Decomposers Diversity • Species Richness • Species Evenness • “Functional Diversity” – emphasis on species contributions, rather than on the species themselves. • Ties in with Ecosystem Functioning – Rivet Hypothesis – Redundancy Hypothesis Control of Community Structure • “Top-Down” Control – Top predators “control” community structure. • “Bottom-Up” Control – Producers/Herbivores “control” community structure • Foundation Species – establish & facilitate colonization by others. • Keystone Species – Large roles in community, controlling other species’ fates. • Invasive Species – “new” species with few predators & fast growth. Biogeography: Large-Scale Distributions • Dispersal & Dispersal Mechanisms – Long-range vs. Short-range • Range expansion or compression – Potential vs Actual Range – Accidentals – Non-native species • Equator-Pole gradients • Altitude gradients Alititudinal Gradients • Rain Shadow Biosphere • Global Climate Change… Biosphere • Global Climate Change…