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Unit II The Living World
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Ecology The study of organisms and how they relate to their environment (habitat). Habitat Biotic Abiotic
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Biotic Hierarchy Organism Populations Communities Ecosystem Biosphere
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Energy Only flows one way through the earth.
Critical matter or nutrients are cycled to sustain life. Sun is the ultimate source of energy.
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Energy As energy flows through each step of a food web, it becomes more unusable. Energy is converted into unusable forms (i.e. heat). Endothermic organisms are ecologically expensive. Converted for an organisms’ own respiration, metabolism, digestion, & predation. Parts of organisms do not provide calories. bones, scales
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Respiration Rate of energy used at each level to maintain life.
More levels = less energy available in a usable form at next higher level. Shorter food chains are more efficient but lack diversity.
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Pyramid of numbers. This pyramid is for a hypothetical area of temperate grassland; in this example, 10,000 grass plants support 10 mice, which support one bird of prey. Based on the number of organisms found at each trophic level, a pyramid of numbers is not as useful as other ecological pyramids. It provides no information about biomass differences or energy relationships between one trophic level and the next. (Note that decomposers are not shown.)
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Pyramid of biomass. This pyramid is for a hypothetical area of temperate grassland. Based on the biomass at each trophic level, pyramids of biomass generally have a pyramid shape with a large base and progressively smaller area for each succeeding trophic level. (Note that decomposers are not shown.)
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Pyramid of energy. This pyramid indicates how much energy is present in the biomass at each trophic level in a salt marsh in Georgia and how much is transferred to the next trophic level. Note the substantial loss of usable energy from one trophic level to the next; this loss occurs because of the energy used metabolically and given off as heat. (Note that decomposers are not shown. The 36,380 kcal/m2/year for the producers is gross primary productivity, or GPP.)
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Gross Productivity The rate of conversion of solar energy into chemical energy. Gross productivity Net Productivity
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Variations in PP per Ecosystem
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Evolution Evolution Works through a combination of 4 processes:
Mutation Natural Selection Gene Flow Genetic Drift
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Speciation What is speciation?
Populations change due to adaptations, natural selection, and mutations.
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Speciation Species Adaptations Morphological Physiological Behavioral
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Speciation Methods Most common new species formation method occurs in two phases: Geographic Isolation Reproductive Isolation Combined process is known as divergent evolution.
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Speciation Methods Adaptive Radiation Coevolution
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Natural Selection Directional 2. Divergent/Diversifying 3. Stabilizing
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Ecosystem Components Population Diversity & Density Niche Diversity
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Producers and Consumers
Producers (Autotrophs) Consumers (Heterotrophs)
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Consumers Primary Consumers Secondary Consumers Tertiary Consumers
Omnivores Scavengers
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Consumers Detritivores Decomposers
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Specialist Species Definition Advantages Disadvantages Example: Koalas
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Generalist Species Definition Advantages Disadvantages Example:
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Other Species Classifications
Keystone Species Definition Indicator Species
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Limiting Factors Law of Tolerance Threshold Optimum Range
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Limiting resource. An organism is limited by any environmental resource that exceeds in tolerance or is less than its required minimum.
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Competition Survival of the Fittest Interference Exploitation
Competitive Exclusion
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Avoidance Resource Partitioning
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Avoidance Character Displacement
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Symbiosis Parasitism Mutualism Commensalisms
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Predation Importance Predator-Prey Relationship
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Predation Enhancements
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Succession Definition Primary Succession Typical Progression
Lichen mosses grasses shrubs forests
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Secondary Succession Where does it occur?
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Stability Based on 3 parameters Inertia Constancy Resilience
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