3Ecological Organization Organism ~ one member of one speciesPopulation ~ all members of one species in a given areaCommunity ~ all populations in a given areaEcosystem ~ all members of community plus abiotic factors in the areaBiome ~ group of ecosystems with same climate and organisms
7SuccessionPrimary Succession = colonization of NEW land by pioneer species until a climax community is reached.Lava flow lichens mosses grasses shrubs treesSecondary Succession = existing community is destroyed and a new one begins to formOccurs more quickly than primary succession because soil is already present and seeds were left behindForest Fire mosses grasses shrubs trees
8Ecosystem Relationships Niche vs. HabitatIf an organism’s habitat is its address, its niche is its occupation.CompetitionOrganisms of same or different species try to use same resource at same place during same time.Competition can be reduced by developing different niches.Ex. 3 species can easily live in same tree if one eats leaves, one eats bark and another eats the flowers.Predator-PreyOrganism doing killing = predatorOrganism being killed = prey
9Symbiosis Mutualism – both species benefit from the relationship Flowers may feed on insects, which may in turn disperse pollen to other flowersCommensalism – one species benefits and the other is unaffected by the relationshipBarnacles attach to the skin of a whale to catch more food particlesParasitism – one species benefits and the other is harmed by the relationshipTapeworms live inside a human intestine and feed from the human
10Energy Flow Producers (autotrophs) Consumers (heterotrophs) Use sunlight to make their food and energy through photosynthesis or chemosynthesisOnly plants and some bacteria/algae are autotrophicConsumers (heterotrophs)Must acquire their energy from other organismsHerbivores = eat plants onlyCarnivores = eat animals onlyOmnivores = eat both plants and animalsScavengers = eat dead or decaying plants and animalsDecomposers = break down dead or decaying plants or animals
11Feeding Relationships Food Chains = series of steps in which organisms transfer energy by eating and being eatenArrow shows the direction of energy transfer in the food chainEx. Grass Grasshopper Mouse Snake Hawk
12Feeding Relationships Food web = links all food chains together in an ecosystem
13Trophic LevelsProducers – get energy from sun & use some for own metabolismPrimary Consumers – get 10% of original energy from producers and use some for own metabolismSecondary Consumers – get 10% of energy from primary consumers and use some for own metabolismTertiary Consumers – get 10% of energy from secondary consumers and use some for own metabolism
15Populations Population Growth If birth rate is larger than death rate = growingIf birth rate is smaller than death rate = shrinkingImmigration = movement into a populationEmigration = movement out of a population
16Populations Exponential Growth (J-shaped Curve) Occurs when individuals reproduce at a constant rate (ex. every individual has 2 kids)Will occur under ideal conditions with unlimited resources
17Populations Carrying Capacity (S-shaped Curve) A population’s growth slows or stops following a period of exponential growthCarrying capacity = largest number of individuals that a given environment can support
18Populations Limiting Factors A factor that causes a population’s growth to decreaseCompetition, predation, disease, climate extremes, human disturbanceDensity-dependent vs. Density-independentDensity-dependent = limit a population according to population sizeCompetition, predationDensity-independent = affects all populations the same, regardless of sizeNatural disasters
19Human Environmental Impacts Human population is growing exponentially with no slowing in sight because of technological advances in medicine.Humans are clearing habitats of plants and animals to have more room for cities & suburbs as well as space to grow more food for the growing populations.
20Human Environmental Impacts Ozone depletionOzone protects us from harmful UV radiation from the sunChlorofluorocarbons (CFCs) destroy the ozone layerCFCs are banned, but their affects are lasting as the ozone layer slowly heals itself
21Human Environmental Impacts Global WarmingBurning of fossil fuels adds excess carbon dioxide in the atmosphereCarbon dioxide is an insulator and traps heat in the atmosphere causing the global temperature to slowly rise.Higher global temperatures could have devastating effects such as melting of glaciers and changes in weather patterns.
22Human Environmental Impacts Pesticide UseDDT and other pesticides are dangerous because they can contaminate groundwater and other water sources.Biological magnification – concentrations of a harmful substance increase in organisms at higher trophic levels in a food web or a food chain.Ex. algae pick up toxin from water they live in – plankton eat much algae to survive – small fish eat the plankton – large fish eat the large fish there is much more DDT in the large fish than the plankton because it has concentrated up the food chain.
23Practice Questions decreased birth rate and increased death rate 1. Which situation would result in the greatest increase in the human population?decreased birth rate and increased death rateincreased infant mortality and decreased death ratedecreased death rate and increased birth rateincreased birth rate and increased infant mortality2. In a forest ecosystem, which is an abiotic factor?the amount of rainfallthe size of the deerthe type of treesthe number of birds3. In the carbon cycle, atmospheric carbon dioxide is converted into organic material by which process?cellular respirationdecompositionphotosynthesistranspiration4. Why do ecosystems rarely contain more than a few trophic levels?Energy transfer efficiency is high.Energy transfer efficiency is low.Energy amounts remain constant.Energy cannot flow through levels.
24Practice Questions5. Recent climate data suggests a global warming trend. The most likely cause could be an increase in which gas?oxygencarbon dioxidenitrogenhydrogen sulfide6. Silt and nutrients from eroding farmland flow into a lake. As a result, which will most likely increase first?fish populationshore vegetationalgae growthdissolved oxygenA community is studied and several interactions are observed and recorded.Which type of interaction could illustrate the process of mutualism?interaction Ainteraction Binteraction Cinteraction D