Topic 5: Ecology

Topic 5: EcologyAlso topic G.51ReadingsIB Book pages 112 133, 142 150, 589 595

2Topic 5.1 Communities and Ecosystems

35.1.1 Key TermsSpeciesHabitatPopulationCommunityEcosystemEcology

Species group of organisms that can interbreed and produce fertile offspring (share gene pool)Habitat - the location of a living organism, where a species lives (cliff face, tidal pool, large intestine)Population group of organisms of same species in same area at same timeCommunity group of populations living and interacting within an area (forest community, kelp forest community)Ecosystem community and abiotic environment. Where a group of interacting populations live.Ecology study of relationships between living organisms and between organisms and their environment.44 main components of the environmentHydrosphere waterAtmosphere airLithosphere rocks/soilBiosphere all living organisms

The first 3 are abiotic (nonliving) and include things such as light, heat, minerals, humidity, oxygenBiosphere is biotic (living)and includes plants, animals, bacteria, fungi, protists5Feeding methodsAutotroph synthesize organic molecules from simple inorganic substances.Involves photosynthesis as well as chemosynthesis (a process found in a few extremophile bacteria)Because they make food that other organisms use they are known as producers. Ex) plants, algae, cyanobacteria

6Heterotrophs obtain organic molecules from other organisms (autotrophs or other heterotrophs)Referred to as consumersInclude parasites, omnivores, carnivores, herbivores, detritivores, saprotrophsDetritivores eat nonliving organic matter such as feces. carcasses, dead leavesSaprotrophs live on or in non-living organic matter. Secrete enzymes into the organic matter and absorb products of their digestion. AKA decomposers. Ex) bacteria, fungi

7Food ChainsA sequence showing the feeding relationships and energy flow between species.Arrows show who gets eaten by whomEx) herring seal herring gets eaten by seal

Food web an interconnecting series of food chains.Food webs illustrate the fact that an animal may eat (or be eaten by) more that one animal.8

Marine food web for the Arctic. Phytoplankton generate organic carbon through photosynthetic reactions. Phytoplankton are eaten by the zooplankton, who are in turn eaten by fish, on up to large marine mammals. Organic carbon that settles to the sea floor is usually consumed by marine organisms there.

9

10Trophic LevelsT1 - producerT2 primary consumerT3 secondary consumerT4 tertiary consumerT5 quaternary consumer

Typically only 10% of the energy from one trophic level is incorporated into the next11

IMPORTANT!! Correct IB unit for this pyramid is kilojoules per square meter per year, kJ/m-2y-1. Use this if you have to draw a pyramid of energy!!!! Pyramid of EnergyDo not confuse this pyramid of energy with a pyramid of numbers that show the population sizes of each trophic level, not energy.12Why is energy lost?100% of the food source may not be swallowed (bones etc)Not all of the food is digestibleNot all organisms are eaten. They may just die and decayA great deal of energy is lost as heat during cellular respiration

13Identify the trophic level of each organism in the food webs on slides 9 and 10.

Most food chains have 4 trophic levels although they can have as many as 6.

Click on the link below to create your own food web. After placing the animals in the correct trophic level DO NOT view the web until you have drawn it!http://www.gould.edu.au/foodwebs/kids_web.htm 14Some last words about energy!Producers are the most important organism in the food chain. Sunlight is the initial source of energy for all communities.Sunlight is converted into chemical energy by producers and transferred to consumers in the various trophic levels.Remember that most of the energy fixed by producers is lost as heat as it passed from one trophic level to the next.

15Nutrients Organisms must recycle the C, N, S, and other elements necessary for life to exist. These elements as well as others are trapped in the cells of the organisms body.Decomposers (saprotrophs and detritivores) break down dead organisms and their wastes and make recycling of the nutrients possible165.2 The Greenhouse Effect

17Where is carbon foundIn the biosphere?In the lithosphere?In the atmosphere?In the hydrosphere?

18Carbon cycles between these 4 locationsPhotosynthesis fixes atmospheric carbon into the bodies of plants and algae. This carbon is converted directly into glucose and then into proteins, lipids, and carbohydratesCellular Respiration organic molecules are broken down and carbon dioxide is released.Feeding carbon is moved from one part of the food chain to anotherFossilization carbon is trapped in sediment as coal and oilCombustion burning of biomass and fossil fuels.195.2.1Draw and Label a diagram of the carbon cycle to show the processes involved.

20

215.2.3Explain the relationship between rises in greenhouse gases and the enhanced greenhouse effect.

22Carbon dioxide levels have been rising:Use of machines, factories, transportationBurning of forests to clear land for farmingBurning of wood or coal for energy

In general, CO2 levels have risen as much as 25% since the industrial revolution.Look at the graph on page 124. What causes the fluctuations in the graph?23Greenhouse gasesCarbon dioxide produced from burning of fossil fuelsMethane produced from cattle ranching, decomposition of organic waste, production and distribution of natural gasOxides of nitrogen made from burning fossil fuel, use of organic and commercial fertilizers, industrial processes24How a greenhouse worksAs light penetrates the walls of a glass greenhouse the light strikes the plants and is transformed into heat.Heat has longer wavelengths than light Greenhouse glass is not as transparent to heat energy as it is to light energy so heat is trapped inside keeping air inside the greenhouse warmer that that outside.Carbon dioxide and water vapor are the glass of the earths atmosphere. See page 125 for an explanation!25The greenhouse effect

a) Short wave solar radiation (light)b) light penetrates the atmosphere and passes through the molecules of the atmospherec) Absorption by the ground and conversion to long wave infrared radiation (heat)d)This warms the planet e) Some infrared is lost to space as heatf) Atmospheric gases particularly water vapour, carbon dioxide, methane and CFC'sg) Greenhouse gases absorb infra-red radiation and scatter this rather than letting it escape to space. In effect this traps the heat energy.h) Some light reflects off the outer surface of the atmosphere and never enters26Enhanced greenhouse effectThe increase in greenhouse gases will intensify the Earths natural greenhouse effect.The Earths average temperature will riseWhat impact does the enhanced greenhouse effect have on the planet?27The impact of greenhouse gasesAs human activity generates more greenhouse gases, more heat is retained causing earths temperature to rise.

285.2.4-5.2.5 Precautionary Principlehttp://click4biology.info/c4b/5/eco5.2.htm#four This link has a great explanation of the precautionary principle. Read it AND the supplemental reading at the links on the page.Basically this is an ethical theory which states that we should always attempt to prevent harm even if there is not sufficient data to prove that the activity will have severe negative consequences.Without this principle industry proceeds with activities until it becomes clear that harm is being done.295.2.6 Arctic Ecosystemshttp://click4biology.info/c4b/5/eco5.2.htm#six Read both your book (pages 129-130) as well as the article at click 4 biology. I also have a link to the article at our wiki.Your assessment statement says you must OUTLINE the consequences of a global temperature rise on arctic ecosystems.305.3 Populations

315.3.1 Population DynamicsPopulation size is affected by four main factors:Natality number of new members due to reproductionMortality number of deathsImmigration members arriving from other placesEmigration members leaving the population

325.3.2 Population Growth Curve

This sigmoid curve shows the changes in population size vs. time. In this model the population is expanding into a habitat offering initial low resistance or low limiting factors.

Note the 3 stages in population growth: exponential, transitional, and plateau.__________________________K33Causes of exponential phaseUnder ideal conditions population growth would be exponential (2n where n= number of generations or 1,2,4,8,16,32,64.)Causes:Plentiful resourcesLittle or no competition from othersFavorable abiotic factors such as T, dissolved oxygenLittle or no predation or disease34Causes of transitional phaseIncreasing competition for resourcesPredators attracted to the growing food supply in the areaMore disease due to crowding in limited spaceThere will not just be a reduced rate of population growth but also a selection (survival and reproduction) of these individuals within the population best suited to using, accessing the resources. Natural Selection is occurring. 35Carrying capacityThe maximum number of individuals a habitat can support. Is represented by the letter K.Carrying cappacity is defined by limiting factors which may include:Availability of resourcesBuild up of wastes (excrement and CO2)PredationDisease

What is the carrying capacity of the earth?It seems that the human population is continuing to increase. Is there evidence that the earth is nearing its carrying capacity for humans? Explain your answer in a 3-5 paragraph essay. Be sure to cite sources that you use.G5 Population EcologyG.5.1 G.5.4

r and K strategistsr strategy refers to species who produce disposable offfspring! Most invertebrates and lower vertebrates can be classified as r strategists. Offspring are many, require little or no care, mature rapidly. Die quickly. Opportunistic. Ex.) bacteria

K strategy refers to species who produce few offspring and nurture them. The time and effort invested in the young increases the probability that they will survive

Study the life history table on pg. 590 of your text and be able to compare r and K strategy species.In unstable environmental conditions, is it better to be a r or K strategist? Why?

Ecological disruption favors r strategists. The organisms that can successfully survive the disruption are often considered pests by humans. Invasive species are also typically r strategists.Estimating population sizeScientists use the capture-mark-release-recapture method to do this.Animals are captured and marked in some way then released. A second sample is captured in which some of the animals will be marked and others will not be marked.See formula on page 591 to calculate population sizeLab!!!G.5.4 Estimating size of commercial fish stockHow do scientists gather quantitative data about commercially important fish?Survey fishermenResearch vesselsRandom samplingEcho soundingMeasuring age of caught fish otoliths, scalesCoded tagsMathematical models

Maximum sustainable yieldThe highest proportion of fish that can be removed from the total population without jeopardizing the maximum yield in the future.

What problems exist if the fish stock is too small or too large?Promoting fish conservationFish stocks are declining. Commercial fishing may become nonexistent. Read page 594.

NOAA Fishwatch link from Hotlink 18.25a http://www.nmfs.noaa.gov/fishwatch/ Example: Brown shrimp http://www.nmfs.noaa.gov/fishwatch/species/brown_shrimp.htm Marine stewardship link from Hotlink 18.25b http://www.msc.org/