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TOPIC 5: ECOLOGY. Adapted from: Mr. Lajos Papp The British International School , Budapest. 5.1 Communities and ecosystem s. Ecology : the study of relationships between living organisms and between organisms and their environment.
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TOPIC 5:ECOLOGY Adapted from: Mr. Lajos Papp The British International School, Budapest
5.1 Communities and ecosystems Ecology: the study of relationships between living organisms and between organisms and their environment. Species: a group of organisms which can interbreed and produce fertile offspring. 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 (non-biological) environment. Autotroph: an organism that synthesizes its organic molecules from simple, inorganic substances (uses an external energy source): plants. Heterotroph: an organism that obtains organic molecules from other organisms: animals, fungi. Distinguish between autotroph and heterotroph.
Consumer: an organism that ingests other organic matter that is living or recently killed. Detritivore: an organism that ingests non-living organic matter.Typical terrestrial detritivores are earthworms, woodlice, millipedes, vultures and hyenas. Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion: fungi and bacteria. Distinguish between consumers, detritivores and saprotrophs.
Food Chain • Food chains illustrate feeding relationships between parent members of a community. 1. oak tree caterpillar great tit sparrow hawk 2. grass seed pheasant fox imperial eagle 3. reed carp pike otter 4. plant (such as nectar) fly spider shrew owl 5. rosebushsap aphid ladybird spider insectivorous bird hawk
Trophic level: the position that an organism occupies in a food chain OR a group of organisms in a community that occupy the same position in food chains. Define trophic level. - The first trophic level is occupied by the autotrophic organisms, the so-called producers. The organisms of the second trophic level are called primary consumers; those of the third level are secondary consumers, and so on. - Producers: are autotrophic organisms, and are mainly green plants. The major producers of aquatic ecosystems (freshwater and marine) are algae. On the land the major producers are the more advanced plants, namely coniferophytes and angiospermophytes, which form forests and grasslands.
- Primary consumers: feed on primary producers. On land, typical primary consumers include insects, reptiles, birds as well as mammals. In aquatic ecosystems the primary consumers are typically small crustaceans and molluscs. Primary consumers also include parasites (fungi, plants or animals) of plants. - Secondary and tertiary consumers: secondary consumers feed on primary consumers. Tertiary consumers feed on secondary consumers. Secondary and tertiary consumers may be predators, which hunt, capture and kill their prey; or parasites, in which case they are smaller than their hosts are.
Decomposers: when plants and animals die their bodies still contain energy and raw materials, as do the waste products such as urine and faeces which they deposit during their lives. These organic materials are decomposed by micro-organisms, namely fungi and bacteria. Fragments of decomposing material are called detritus, and many small animals (called detritivores) feed on these, contributing to the process of breakdown.
Describe what is meant by a food chain giving three examples, each with at least three linkages (four organisms). Only real examples should be used from natural ecosystems. A B indicates that A is being `eaten` by B (that is, the arrow indicates the direction of energy flow). Each food chain should include a producer and consumers, but not decomposers. http://www.kidsknowit.com/interactive-educational-movies/free-online-movies.php?movie=Food%20Chains Named organisms at either species or genus level should be used. Common species names can be used instead of binomial names. General names such as tree or fish should not be used.
A food webis a diagram that shows all the feeding relationships in a community. Complete food web diagrams are very complex. It has a number of advantages over a food chains including: • shows the much more complex interactions between species withina community/ ecosystem • - more than one producer supporting a community • - a single producer being a food source for a number of primary consumers • - that a consumer may have a number of different food sources on the same or different trophic levels
Describe what is meant by a food web. Deduce the trophic level of organisms in a food chain and a food web. The student should be able to place an organism at the level of producer, primary consumer, secondary consumer, and so on, as the terms herbivore and carnivore are not always applicable. Construct a food web containing up to 10 organisms, using appropriate information.(see Click4Biology)
The energy that passes to detritivoresandsaprotrophsis eventually released by cell respiration and lost as heat. In most communities all the light energy that was trapped by producers is ultimately lost as heat after flowing through the food chain. Explain the energy flow in a food chain. Energy losses between trophic levels include material not consumed or material not assimilated, and heat loss through cell respiration. Energy transformations are never 100% efficient (commonly being 10-20%).
A pyramid of energy: the most fundamental and ideal way of representing relationships between organisms in different trophic levels. This has a number of advantages: - It takes into account the rate of production, in contrast to pyramids of numbers and biomass which depict the standing states of organisms at a particular moment in time. Each bar of a pyramid of energy represents the amount of energy per unit area or volume that flows through that trophic level in a given time period.
5.1.11 State that energy transformations are never 100% efficient • When energy transformations take place, including those in living organisms, the process is never 100% efficient. Commonly, it is between 10-20%.
THE GREENHOUSE EFFECT Carbonis found in one of four 'pools‘ : - biosphere - oceans - atmosphere - sediments Carbon is moved between these four pools by a variety of biological, geochemical or industrial processes.
Processes - Photosynthesis by terrestrial plants and aquaticalgae in which atmospheric (and dissolved) carbon dioxide is removed and fixed as organic compounds such as carbohydrate, lipid and protein. - Cell respiration by all organisms in which they metabolize organic molecules releasing carbon dioxide. - Fossilization in which carbon as organic molecules becomes trapped in sediment as coal, gas and oil. - Combustion during the burning of fossil fuels and burning of biomass.
Greenhouse effectis a natural process that creates moderate temperatures on earth to which life has adapted. The earth has relatively little carbon dioxide in its atmosphere compared to a planet like Venus which has an atmosphere of CO2 x 200,000 times greater and a surface temperature nearly twenty times higher than earth. Enhanced greenhouse effectthe activities may be increasing the levels of carbon dioxide and other 'greenhouse gases' such as methane and oxides of nitrogen in the atmosphere. This may lead to increased global temperatures and climate change.
Greenhouse effect - short wave solar radiation (light) - light penetrates the atmosphere and passes through the molecules of the atmosphere - absorption by the ground and conversion to long wave infrared radiation (heat) - this warms the planet - some infrared is lost to space as heat
- atmospheric gases particularly water vapor, carbon dioxide, methane, CFCs and oxides of nitrogen - absorb infra-red and scatter this rather than letting it escape to space effectively trapping the heat - some light reflects off the atmosphere and never enters - if greenhouse effect did not exist, the average global temperature would be -170C.
The enhanced greenhouse effect - Increase in carbon dioxide and other greenhouse gases will increase the particles in the atmosphere. - Therefore more infra-red will be absorbed, scattered and retained as heat. - The average global temperatures will rise. Some models suggest as much as 40C in the next 50 years. - An enhanced greenhouse effect is predicted to cause global climate changes. This is often referred to as global warming but whilst the average global temperatures may rise, the local effects may vary widely.
5.2.2 Analyze the changes in concentration of atmospheric carbon dioxide using historical records
The 'Precautionary Principle'suggests that if we wait until it is proven that humans are causing climate change, it will be too late. That is better to respond now as a precaution even if in the long term it turns out that the case cannot be made. Outline the precautionary principle. The precautionary principle holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding. This is the reverse of the normal situation, where those who are concerned about the change would have to prove that it will do harm in order to prevent such changes going ahead.
http://www.geo.arizona.edu/dgesl/research/other/climate_change_and_sea_level/sea_level_rise/sea_level_rise.htmhttp://www.geo.arizona.edu/dgesl/research/other/climate_change_and_sea_level/sea_level_rise/sea_level_rise.htm http://maps.grida.no/go/graphic/climate_change_and_vector_borne_diseases http://maps.grida.no/go/graphic/african-wildlife-under-threat-from-climate-change http://geongrid.geo.arizona.edu/arcims/website/slrworld/viewer.htm
Climateis a complex phenomenon. This makes the exact predictions of location and timing it difficult. It is, however, possible to hypothesis about the general effects: - increased frequency and intensity of droughts; - flooding as a result of higher rainfalls, increased snowmelts, and rising sea levels, - declines in food production,
- increased disease: infectious pathogens are really reduced by cold temperatures, warmer temperature will allow pathogens to survive better, - current evidence suggests that both malaria and dengue fever are currently extending their distribution, - more extreme weather, - loss of biodiversity.
Precautionary principle and the enhanced greenhouse effect - The precautionary principle suggests that the effects of climate change are sufficiently serious that we ought not to wait until the effects of the enhanced greenhouse effect, climate change, have been proved. - Since measures to reduce climate change need to be taken as a matter of urgency, we do not have the luxury of time to wait the proof. If we did so then the effects would be so far advanced that serious damage would already have occurred.
Evaluate the precautionary principle as a justification for strong action in response to the threat posed by the enhanced greenhouse effect. Consider whether the economic harm of measures taken now to limit global warming could be balanced against the potentially much greater harm for future generations of taking no action now. There are also ethical questions about whether the health and wealth of future human generations should be jeopardized, and whether it is right knowingly damage the habitat of, and possible drive to extinction, species other than humans.
The environmental angle here is that the issue of global warming is, by definition, a genuinely global one in terms of causes, consequences and remedies. Only through international cooperation will a solution be found. There is an inequality between those in the world who are contributing most to the problem and those who will be mostharmed. http://www.thearctic.is/articles/overviews/ecosystem/enska/index.htm
5.2.6 Outline the consequences of a global temperature rise on arctic ecosystems. • Melting of ice shelves, resulting in a global rise in sea level • Disruption arctic food chains with potential species extinction. • Release of carbon from organic matter in previously frozen soil. • Increased success of pest species, including pathogens.
5.3 Populations • Natality- birth rate. • Mortality- death rate. • Immigration- # members moving in. • Emigration- # members moving out. • Population change = (natality + immigration) – (mortality + emigration)
Factors increasing population size - Natality is recruitment to a population through reproduction. - Immigration from external populations e.g. bird migration. Factors reducing population size - Mortality which is the death rate from any source e.g. predation. - Emigration where individuals leave the population for another habitat.
5.3.2 Draw and label a graph showing the sigmoid (S-shaped) population growth curve
5.3.3 Explain reasons for the exponential growth phase, the plateau phase and the transitional phase between the two. • Exponential growth phase- initially, when population sizes are small, there are little to no limiting factors. • Transitional phase- as population size increases, competition for resources becomes more prominent, and the growth rate slows • Plateau phase- the population is near or at carrying capacity.
5.3.4 List three factors which set limits to population increase. • Density Dependant: • Food • Territory • Density Independent: • Natural Disasters (flood, avalanche, earthquake, etc.)
List seven levels in the hierarchy of taxa (singular: taxon) - kingdom, phylum, class, order, family, genus and species - using an example from two different kingdoms for each level.
