4.1 Species, communities and ecosystems The continued survival of living organisms including humans depends on sustainable communities. Define the Following Terms • Species • Habitat • Population • Community • Ecosystem • Ecology • Species: A group of organisms that can interbreed and produce fertile offspring • Members of a species may be reproductively isolated in separate populations • Habitat: The environment in which a species normally lives or the location of a living organism • Population: A group of organisms of the same species who live in the same area at the same time • Community: A group of populations living and interacting with each other in an area • Ecosystem: a community and its abiotic environment • Has the potential to be sustainable over long periods of time • Ecology: The study of relationships between living organisms and between organisms and their environment Autotrophs vs. Heterotrophs • Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances from the abiotic environment • These inorganic nutrients are maintained by nutrient cycling • Heterotroph: an organism that obtains organic molecules from other organisms • Few species can have both methods (Ex: venus flytrap, certain Euglena and corals) Differences between consumers, detritivores, and saprotrophs? • Consumers: an organism that ingests other organic matter that is living or recently dead • Detritivore: an organism that ingests non-living organic matter (detritus) • Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes onto it and absorbing the products of digestion (external digestion) DBQ Pg. 204: Unexpected diets • Pg. 209: Chi Squared Testing 4.2 Energy Flow • Essential idea: Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat. • Nature of Science Use theories to explain phenomena: the concept of energy flow explains the limited length of food chains. Sunlight and ecosystems • Most ecosystems rely on a supply of energy from sunlight DBQ • Please complete DBQ: Insolation on page 214 Energy Conversion • Light energy is converted to chemical energy in carbon compounds by photosynthesis Energy in food chains • Chemical energy in carbon compounds flows through food chains by means of feeding. • https://www.youtube.com/watch?v=iWfEn8J5xK M Respiration and Energy Release • Energy released by respiration is used in living organisms and converted to heat. • All living things need energy for cell activities such as: - synthesizing large molecules like DNA, RNA, and proteins. - pumping molecules or ions across membranes by active transport - Moving things around inside the cell, such as chromosomes or vesicles, or the protein fibers in muscle cells (actin and myosin) DBQ • Page 216 of text • How does the ambient temperature of the magpie cage affect its body metabolism? Enjoy • https://www.youtube.com/watch?v=cWhXKhh8xo Heat Energy in Ecosystems • Living organisms cannot convert heat to other forms of energy. • **Living organisms can perform various energy conversions. i.e • • • • Light energy to chemical energy (photosynthesis) Chemical energy to kinetic energy in muscle contraction. Chemical energy to electrical energy in nerve cells. Chemical energy to heat energy in heat-generating adipose tissue. THEY CANNOT CONVERT HEAT ENERGY INTO ANY OTHER FORM OF ENERGY. DBQ’s Please complete the following DBQ on page 219: A simple food web Pyramids of Energy • The amount of energy converted to new biomass by each trophic level in an ecological community can be represented with a pyramid of energy. • What is meant by the 10% rule? Pyramids of Energy ** Note- Please use stepped diagrams, not triangular Energy Pyramids 1. What do the trophic levels represent? (1, 2, 3, 4….) 2. What do the percentages represent? 3. Why is it in the shape of a pyramid? 4. Why do the percentages decrease as the pyramid Energy per unit area (community) per increases? unit time: kJm-2yr-1 4.3 Carbon cycling Making accurate quantatative measurements- it is important to obtain reliable data on the concentrations of carbon dioxide and methane in the atmosphere. Carbon Fixation • Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds • Carbon dioxide diffuses from the atmosphere or water into autotrophs • In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate ions • Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere Methane • Produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground • Three different groups of bacteria involved: 1. Bacteria that convert organic matter into a mixture of organic acids, alcohol, hydrogen and carbon dioxide 2. Bacteria that use organic acids and alcohol to produce acetate, carbon dioxide and hydrogen 3. Archaens that produce methane from carbon dioxide, hydrogen and acetate. They do this by 2 chemical reactions • Methane is oxidized into carbon dioxide and water in the atmosphere Peat • Forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions of waterlogged soils • Used as a nonrenewable energy source or to alter the pH of gardens • Partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks • Coal was made from peat that was buried beneath sediment and heated • Oil and gas formed in the mud at the bottom of seas and lakes and heated Carbon Dioxide Production • If organic matter is heated in the presence of oxygen to its combustion temperature, it will set light and burn • The oxidation reaction is called combustion • The products to complete combustion are carbon dioxide and water Pg. 224 in workbook: The Carbon Cycle Limestone • Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilized in limestone • Contains a large amount of the earth’s carbon Discuss… Skills • Construct a diagram of the carbon cycle • THEN read Carbon fluxes on page 227 • THEN complete the DBQ on page 227 4.4 Climate Change • Assessing claims: assessment of the claims that human activities are not causing climate change. • What is the evidence? • Let’s ponder… What is the Greenhouse Effect? Long-wavelength emissions from Earth • The warmed surface of the Earth absorbs short-wave energy from the sun and then re-emits it, but at much longer wavelengths. • Most re-emitted radiation is infrared • Longer-wave radiation is reabsorbed by greenhouse gases which retains the heat in the atmosphere. Back to Carbon Dioxide • Greenhouse Gases- trap heat in the atmosphere, which makes the Earth warmer -Carbon dioxide and water vapor are the most significant greenhouse gases. Carbon dioxide • Released into the environment by cell respiration in living organisms. • Released into the atmosphere by combustion of biomass and fossil fuel . • Removed from the atmosphere by photosynthesis and by dissolving in the oceans. Industrialization and climate change • There is a correlation between rising atmospheric concentrations of carbon dioxide since the start of the industrial revolution two hundred years ago and average global temperatures. Water Vapor • Water vapor is formed by evaporation from the oceans and also transpiration in plants. • Water vapor is removed from the atmosphere by rainfall and snow (precipitation). Other Greenhouse Gases • Other greenhouse gases including methane (CH4) and Nitrogen oxides have less impact. • Methane- Emitted from marshes and other waterlogged habitats, organic landfill sites; Released during extraction of fossil fuels and the melting of the polar ice caps. • Nitrous oxides- emitted through agriculture (fertilizer), burning of fossil fuels, and industry (production of fertilizer), by some bacteria Oxygen and Nitrogen • ***Are Not Greenhouse Gases • They do not absorb longer-wave radiation • Note: • All of the greenhouse gases together make up less than 1% of the total atmosphere. Impact • Two Factors together determine the warming impact of a greenhouse gas. • 1. How readily the gas absorbs long-wave radiation. • 2. The concentration of the gas in the atmosphere . • For example, methane causes much more warming per molecule but there is much less methane than carbon dioxide and therefore less of an impact on the environment. Percent Absorbed • 25-30% of short-wave radiation is absorbed by the atmosphere before it reaches the earths surface. • Most is infrared and absorbed by ozone. • 70-75% of solar radiation therefore reaches earths surface and much is converted to heat. • A higher percentage of long-wave radiation is absorbed after being re-emitted by the earth's surface. • Between 70-85% is captured by greenhouse gases and contributes to global warming. Without it, the earths mean temperature would be -18°C. Global temperatures and carbon dioxide concentrations • Correlations between global temperatures and carbon dioxide concentrations on Earth. DBQ • Complete DBQ on page 233: CO2 concentrations and global temperatures. Greenhouse gases and climate patterns • Global temperatures and climate patterns are influenced by concentrations of greenhouse gases. • Surface temperatures are estimated to be 32° C higher due to greenhouse gases. • Therefore, more greenhouse gas, more retained heat from radiation. DBQ • Read and complete DBQ: Phenology on page 234 • Phenology- the study of timing patterns in seasonal activities in animals and plants. Burning Fossil Fuels • Recent increases in atmospheric carbon dioxide are largely due to increases in the combustion of fossilized organic matter. • Read and complete DBQ on pages 235-236 : Comparing CO2 • And DBQ on page 237: Uncertainty in temperature rise projections. Assessing claims and counter claims • Research and summarize two articles on the issue at hand. • Read page 236 and 237 • Assessing claims and counter claims: assessment of claims that human activities are not causing climate change. • Opposition to the climate change science: Evaluating claims that human activities are not causing climate change. Ecology Option C.1 Species and Communities Ecology • The study of relationships between organisms and their natural environment. • It underpins conservation efforts to preserve the earths biodiversity. What is a keystone species? • https://www.youtube.com/watch?feature=player_e mbedded&v=_IWw8Ruz8Uo • https://www.youtube.com/watch?feature=player_e mbedded&v=dIUo3STj6tw Limiting Factors • The distribution of a species is affected by limiting factors. We can describe a limiting factor as a resource that is most scarce in relation to an organism’s needs. Examples • Plant Distribution- limited by abiotic factors • plant species common to the tropics are not Adapted for survive frosts. • Animal Distribution- affected by temperature, water, breeding sites, food supply, and territory. DBQ • Please read and complete DBQ- Intertidal Zonation • Page 605-606 Skill- Using transects • Use of a transect to correlate the distribution of plant or animal species with an abiotic variable. • Text pages 604 and 605 • Explain the types of transect used in research today. Using Ecological Models • Use models as representations of the real world: zones of stress and limits of tolerance graphs are models of the real world that have predictive power and explain community structure. C.1 A.1 Application 1 • Distribution of one animal and one plant species to illustrate limits of tolerance and zones of stress. • Read and complete exercise on pages 607-608 C.1 A.3 Application 3 • The symbiotic relationship between zooxanthellae and reef-building coral reef species. Understanding 4 Application 2 Interspecific interactions • U4- Interactions between species in a community can be classified according to their effect. • A2-Local examples to illustrate the range of ways in which species can interact within a community. The Niche Concept • Each species plays a unique role within a community because of the unique combination of its spatial habitat and interactions with other species. • Spatial habitat- where a species lives Competitive Exclusion Principle • Two species cannot survive indefinitely in the same habitat if their niches are identical. • Russian scientist, Gause’s experiment on two species of paramecium. Competitive Exclusion Principle DBQ’s• Please complete DBQ: Competitive exclusion in cattails • Page 609 • Please complete DBQ: Character displacement in ants Fundamental vs. Realized Niches • Analysis of a data set that illustrates the distinction between fundamental and realized niche. • Fundamental Niche- potential mode of existence. Refers to the broadest of ranges a species can occupy given its set of adaptations. • Realized Niche- actual mode of existence. Results from the combination of its adaptations and competition with other species. Keystone species • Community structure can be greatly affected by keystone species C.2 Communities and ecosystems Use models as representations of the real world- pyramids of energy model the energy flow through ecosystems. Trophic Levels • Trophic Levels: the feeding positions in a food chain • Producer • Primary Consumer • Secondary Consumer • Tertiary Consumer • Most species occupy different trophic levels in multiple food chains Food Web • Shows all the possible food chains in a community Production • Rate of generation of biomass in an ecosystem • Production in plants happens when organic matter is synthesized by photosynthesis • In animals it occurs when food is absorbed after digestion • The percentage of ingested energy converted to biomass is dependent on the respiration rate • Energy is measured in kJ/m2/yr • Gross production- total amount of organic matter produced per unit area per unit time by a trophic level in an ecosystem • Net production- amount of gross production remaining after subtraction of the amount used for respiration by the trophic level 1. Calculate the net productivity of the autotrophs. 2. Compare the percentage of heat lost through respiration by the autotrophs and heterotrophs. 3. Identify a reason for heat loss differences in animals vs. plants. 1. 19,580 kJ/m2/yr 2. Autotrophs lose 55% of their gross production to heat; animals lose 96% of their energy to heat 3. Animals use a lot of energy to move/maintain body temperature • The length of food chains is determined by the level of net primary production • The higher the productivity, the longer the food chains Conversion Ratio • The quantity of dietary input in grams required to produce a certain quantity of body mass in livestock or fish. • Ex: A feed conversion ratio of 1.2 means that 120g of feed are required to produce 100g of body mass • Lower feed inputs means lower energy inputs for food production • In a closed ecosystem, energy but not matter is exchanged with the surroundings Climographs • Climate is a property that emerges from the interaction of precipitation and temperature • The type of stable ecosystem that will emerge in an area is predictable based on climate • A climograph is a diagram which shows the relative combination of temperature and precipitation in an area Gersmehl Diagrams • Model of nutrient storage and flow in a terrestrial ecosystem • Three storage compartments: Biomass, Litter, Soil • Litter: This is the surface layer of vegetation, which over time breaks down to become soil • Biomass: The total mass of living organisms per unit area. • Arrows represent nutrient flows; thickness represent the rate of flow • Human activity can accelerate nutrient flows into and out of ecosystems • Ex: Growth followed by transport of crops out of an area depletes the area of the nutrients that were locked into the crops, thus nutrients need to be added to the soil Succession • Disturbances that influence the structure and rate of change within ecosystems • Primary- an environment where soil has been disturbed/needs to be formed • Secondary- where an ecosystem has recently been located/soil undisturbed Primary Succession • Occurs in an environment in which new substrate, devoid of vegetation and usually lacking soil, is deposited • Occurs after: • Volcanoes • Glacier activity • Lichens are usually the first things to grow (pioneer species) • Lichen: mold and fungus living mutualistically • Lichens break down rock into soil to allow for plants to grow lichen, moss, ferns, angiosperms, conifers/gymnosperms Secondary Succession • Secondary succession is a process started by an event that reduces an already established ecosystem to a smaller population of species • Occurs on preexisting soil • It occurs after: • Harvesting • Deforestation • Hurricane DBQ Pg. 621 C.3 Impacts of Humans on Ecosystems Assessing risks and benefits associated with scientific research: the use of biological control has associated risk and requires verification by tightly controlled experiments before it is approved. Alien and Invasive Species • Introduced alien species can escape into local ecosystems and become invasive. • Many alien species become invasive the normal limiting factors in their original habitat are missing. • The predators, diseases, and vigorous competitors that controlled numbers in its native habitat are usually absent. Do you know a few examples for your arsenal? Alien species compete with endemic species • Competitive exclusion and the absence of predators can lead to reduction in the numbers of endemic species when alien species become invasive. Case studies of introduced alien species. • Study of the introduction of the cane toads in Australia and one other local example of the introduction of an alien species. • Please read and review Case study on page 627-628 of the text. Evaluation of methods to control alien species • Evaluation of eradication programs and biological control as measures to reduce the impact of alien species. • Complete DBQ page 628: The Mango Mealy bug • Complete DBQ page 629: Control of purple loosestrife The risk of biological control • A biological control can be introduced to an ecosystem to limit an invasive species. This involve introducing natural predators of the invasive species to limit its spread. • What are the risks of introducing another invasive species to an ecosystem? • ***A risk-averse approach to introducing a natural predator to control an invasive species involves holding the natural enemy in approved facility until enough research is gathered to ensure the natural predator will have minimal negative impact. Biomagnification • Pollutants become concentrated in the tissues of organisms at higher trophic levels by biomagnification. The causes and consequences of biomagnification • Analysis of data illustrating the causes and consequences of biomagnification. • Complete DBQ: Biomagnification of caesium page 631-632 DDT Pros vs. Cons Plastics in the ocean • Macroplastic and microplastic debris has accumulated in marine environments. It’s your time!!! C.4 Conservation of biodiversity Entire communities need to be conserved in order to preserve biodiversity. Indicator Species • Indicator Species- an organism used to assess a specific environmental condition • The presence/absence of these species is a good indicator of environmental conditions • Ex: Lichens are pollution-intolerant so their presence indicates clean air. • Ex: The presence of Black Greasewood indicates alkaline and saline soils Biotic Index • Compares the relative frequency of indicator species • Relative numbers of indicator species can be used to calculate the value of a biotic index • The number of individuals of each indicator species is multiplied by a pollution tolerance number, and a weighted average is determined Biodiversity • Biological diversity • Has 2 components: • Richness- number of different species present • Evenness- how close in numbers each species is • Biodiversity is important to preserve. Why? In Situ Conservation of Endangered Species • ”On-site conservation” Protecting an endangered species in its natural habitat, by protecting or cleaning up the habitat, or by defending the species from predators • Places where the animal is found in its own natural habitat and is not allowed to be disturbed by humans • Keeps the animals out of danger zones and allows them to live and reproduce naturally in its own environment. Greater genetic variety is also ensured. • Preserving their habitat allows other species to live there also, thus preserving biodiversity Active Management of Conservation • A procedure for maintaining a species or habitat in a particular area (in-situ conservation) • Control alien species- Those that are not supposed to be in the area are removed • Restore areas where human impact has destroyed the ecosystem by reforestation and species reintroduction • Promote the recovery of threatened species • Control the exploitation by humansLogging is controlled along with land clearing (If trees are cut down, more are planted) Ex Situ Conservation Measures • “Off-site conservation" Protecting an endangered species by removing part of the population from a threatened habitat and placing it in a new location • Captive breeding- animals kept in zoos/parks reproduce to increase in number, with the possibility of reintroducing some of the offspring into the wild • Botanic gardens- sites where many plant species are planted in controlled environments to maintain their species • Seed banks- seeds are kept in cold and dry storage, since they stay in good condition for hundred of years Read the Case Study on pg. 637 of text What are the biogeographical features of nature reserves that promote conservation of diversity? • Edge effects- ecology of edges of NR is different from its central ecology. Ex: The cowbird feeds in open areas but lays eggs on the edges of forests. Forest fragmentation has increased the population of this bird • Size- large NR promote conservation of biodiversity more effectively than small ones • Habitat Corridors- Allow organisms to move between different parts of a fragmented habitat. Ex: tunnels under busy roads Read and answer the 2 DBQs on pg. 640 Simpson Diversity Index • Measure of diversity • Often used to quantify the biodiversity of a habitat • It takes into account the number of species present, as well as the abundance of each species D= Diversity Index N= Total number of organisms of all species n= number of individuals of a particular species Which environment is considered to be more diverse? Sample 1 Sample 2 Daisy 300 20 Dandelion 335 49 Buttercup 365 931 Total 1000 1000 2.99 1.15 C.5 Population Ecology Avoiding bias: a random number generator helps to ensure population sampling is free from bias. Estimating Population Size Using a random number generator Using The Lincoln Index • Use of the capture-mark-recapture method to estimate the population size of an animal species. • Read and review The Lincoln Index on pages 643645 Capture-Mark-ReleaseRecapture Capture-Mark-ReleaseRecapture Capture-Mark-ReleaseRecapture Capture-Mark-ReleaseRecapture The “J” shaped population growth curve • The exponential growth pattern occurs in an ideal, unlimited environment. Natality, Mortality, Immigration and Emigration Natality, Mortality, Immigration and Emigration The Sigmoid graph Carrying Capacity • Population growth slows as a population reaches the carrying capacity of the environment. • Represented by the variable “K” • In the sigmoid growth pattern, when a population reaches its carrying capacity, the population will stop growing and natality and mortality will be equal. Effecting “K” Factors that influence population size • The phases shown in the sigmoid curve can be explained by relative rates of natality, mortality, immigration, and emigration. • Please read and review concepts on page 647 Modelling population growth • Modelling the growth curve using a simple organism such as yeast or species of Lemna. Top-down and Bottom-up limiting factors • Limiting factors can be top-down or bottom-up. The population of organisms in an ecosystem can be influenced by availability of resources like nutrients, food, and space. These factors are referrred to as bottom-up limiting factors. Predation is referred to as top-down limiting factor. MSY C.6 Nitrogen and phosphorus cycles Assessing risks and benefits of scientific research- agricultural practices can disrupt the phosphorus cycle Nitrogen Cycle • All life requires nitrogen-compounds, e.g., proteins and nucleic acids. • Air, (79% nitrogen gas (N2)), is the major reservoir of nitrogen. • Most organisms cannot use nitrogen in this form. • Plants must secure their nitrogen in "fixed" form, i.e., incorporated in compounds such as: • nitrate ions (NO3−) • ammonium ions (NH4+) • urea (NH2)2CO • Animals secure their nitrogen (and all other) compounds from plants (or animals that have fed on plants). Draw and Label • Four processes participate in the cycling of nitrogen through the biosphere: • • • • nitrogen fixation decay nitrification denitrification Nitrogen Fixation • Nitrogen-fixing bacteria convert atmospheric nitrogen to ammonia • Ex: Cyanobacteria, Purple Sulfur Bacteria, Rhizobium Rhizobium • Associates with roots in a mutualistic relationship • The bacteria manufacture ammonia, thus providing nitrogen compounds to the plant, and the plant provides organic compounds from photosynthesis to the bacteria • Mainly on the roots of legumes; exist in root nodules Decay • The proteins made by plants enter and pass through food webs • At each trophic level, their metabolism produces organic nitrogen compounds that return to the environment, chiefly in excretions • Microorganisms break down the molecules in excretions and dead organisms into ammonia Nitrification • The biological oxidation (aerobic process) of ammonia to nitrite followed by the oxidation of the nitrite to nitrate • Bacteria complete this process Ex: Nitrobacter • (Ammonia can be taken up directly by plants — usually through their roots) Denitrification • In the absence of oxygen, denitrifying bacteria reduce nitrate in the soil making Nitrogen gas returning it to the atmosphere Waterlogging • Poor drainage or flooding can lead to waterlogging • Reduces oxygen content of the soil favoring denitrification • Decreases amount of nitrates available in the soil • Waterlogged soil favors the growth of insectivorous plants; the lack of nitrogen in the soil forces plants to obtain nitrogen from insects Phosphorus Cycle • Phosphorus and phosphorus compounds are located in water, soil and sediments • Animals absorb phosphates by eating plants or planteating animals • Phosphorus plays a critical role in cell development is a part of ATP and DNA • Rain and weathering cause rocks to release phosphate ions and other minerals. Phosphate is then distributed in soils and water. • Plants take up phosphate from the soil and are then consumed by animals. The phosphate is incorporated into molecules such as DNA. When the plant or animal dies, it decays, and the organic phosphate is returned to the soil. • In the soil, phosphate can be made available by bacteria that break down organic matter to inorganic forms of phosphorus. This process is known as mineralisation. • Phosphorus in soil can end up in waterways and eventually oceans. Once there, it can be incorporated into sediments over time, thus limiting the availability of phosphorus for agriculture in the future • The leaching of mineral nutrients from agricultural land into rivers causes eutrophication and leads to increased biochemical oxygen demand • Eutrophication- Water acquires a high concentration of nutrients, (phosphates and nitrates), promoting excessive growth of algae. As the algae die and decompose, the water is depleted of oxygen causing the death of other organisms, such as fish.
