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Chapter 12: Biodiversity Lesson Objectives: To define the terms species, habitat and biodiversity To explain how biodiversity may be considered at different levels (habitat, species and genetic) Biodiversity Biodiversity, which is short for biological diversity, is the term used to describe the whole variety of life on Earth (first used by Wilson in 1986). ‘the variety of habitats, communities and species in an area, and the genetic diversity within populations’ We still have not documented/discovered all living organisms on Earth At the moment ~1.5 million species have been described Estimates of total number of species range from 2 to 100 million … but we don’t really know! Dr Terry Erwin (1980s) In Panama, 19 trees were ‘fogged’ with insecticide and the dead individuals were collected Erwin and his team were sampling arthropod diversity (mosquitoes, dragonflies etc.) 1,200 different species of beetle alone were collected Of these ~80% were not previously known Beetles are the largest group of known arthropods (40%) … Erwin extrapolated from his findings to estimate that the number of arthropods is around 30 million!!! But who really cares? … does it really matter if we document all species? The more we understand about the organisms around us (how and where they live etc.), then the more we should be able to protect them and their environment Ecology • The study of interactions that take place between organisms and their environment. • It explains how living organisms affect each other and the world they live in. • Habitat is the place a plant or animal lives • Niche is an organism’s total way of life • What is a SPECIES? (recap from Chapter 13!) Ecology – levels of organisation in living things • • • • • • • Atom Molecule Organelle Cell Tissue Organ System – organism Ecologists have organized the interactions an organism takes part in into different levels according to complexity. Levels of Organisation Organism: An individual living thing that is made of cells, uses energy, reproduces, responds, grows, and develops Population: A group of organisms, all of the same species, which interbreed and live in the same place at the same time. Biological Community: All the populations of different species that live in the same place at the same time. Levels of Organisation Organism Population Ecosystem: Populations of plants and animals that interact with each other in a given area with the abiotic components of that area. (terrestrial or aquatic) Community Levels of Organisation Organism Population Community Biosphere: The portion of Earth that supports life. Biosphere Ecosystem Discussion time … Can biodiversity be considered at different levels? (habitat, species and genetic) Can biodiversity be considered at different levels? Species diversity The variety of living species within a geographic area This can be measured using species richness (the number of species within a particular sample area) together with species evenness (the evenness in numbers of individuals of each species in the area) Ecosystem (habitat) diversity The broad differences in ecosystem types and the diversity of habitats and processes within each type Species distribution and community patterns The role and function of key species Not understood very well as interactions are very complex … you are trying to understand all of the species in an ecosystem, the effects they have on each other and their surroundings whilst also being affected themselves Diverse ecosystems include rainforests Genetic diversity The differences in genetic make-up between distinct species and genetic variation within a species (the least visible and arguably the least studied level of diversity) Variety in alleles, genes and chromosome structure More genetic diversity in a species/population means a greater ability for individuals to adapt to environmental changes … which leads to natural selection and therefore evolution!!! Monoculture in farming = genetically identical plants which could lead to problems in the event of a disease PLENARY – define the following key words! 1.Species 2.Population 3.Community 4.Habitat A group of organisms, all of the same species, which interbreed and live in the same place at the same time. All the populations of different species that live in the same place at the same time. the place a plant or animal lives 5.Biodiversity ‘the variety of habitats, communities and species in an area, and the genetic diversity within populations’ Practical Ecology Lesson Objectives: To find out about practical ecology techniques To complete a practical using quadrats – ‘Investigating the distribution of plants in two habitats, using random sampling’ Equipment … A quadrat – used for systematic sampling (transects) and stratified sampling (comparing two different areas) Comparing the population of daisies in two different areas 20m Count the number of daisies in each quadrat! 1m2 quadrat -10 quadrats in each site Use the random number table to position your quadrat (eg: read down the left hand side) -2 sites 4 2 1 5 3 0m 20m Reviewing practical techniques Lesson Objectives: To review our practical from last lesson To describe how to carry out simple analysis of results To be introduced to Simpson’s Index of Diversity Tasks … STARTER – review practical techniques used last lesson 1. Run through homework (completing tasks 10-14 from practical worksheet) 2. Complete SAQ 1 and SAQ 2 in pairs/individually 3. Peer assess 4. How to sample non-plants! 5. Start to think about a bit of Maths! How to sample things that aren’t plants! Longworth Traps … http://www.youtube.com/watch?v=FDqpXlClJTw How to sample things that aren’t plants! Kick sampling http://www.youtube.com/watch?v=h__fLpsWxcg How to sample things that aren’t plants! Dye marking Salmon for a mark, release and recapture study http://www.youtube.com/watch?v=8Q81ihjzb8U Comparing species evenness Which habitat had the greatest species evenness? POND B – there is less variation in population size between each species If we wanted to compare relative abundance (amount) of each species found in two habitats we can therefore look at the information gathered and draw a conclusion Using statistics … Statistically analysing your results is much more powerful than just comparing your results In this ecology practical, 10 quadrats were laid randomly in each site (Shore A and Shore B) and the number of individuals from each of the species was counted The results are shown in the table Simpson’s Index of Diversity Used to calculate a value of Biodiversity in an area Requires data about the number of species in an area and their densities BONUS – you don’t have to ID all species you find, just note the number of different types (ie: you can label them A, B. C etc!) D Diversity Index value (0-1); 1 = high, 0 = low n Total number of organisms of a particular species N Total number of organisms of all species ‘Sum of’ It can’t be that hard – let’s have a go! First we must calculate n/N for each Species found on Shore A Then we need to square this number D = 1 – 0.201 = 0.799 Finally, add all of the numbers together and take this away from 1 Now for Shore B … First we must calculate n/N for each Species found on Shore A Then we need to square this number D = 1 – 0.267 = 0.733 Finally, add all of the numbers together and take this away from 1 Let’s compare … The higher the number, the greater the diversity! Species richness Simpson’s Index of Diversity Shore A = 8 (8 different species!) Shore A Shore B = 7 Shore B More D = 0.799 diverse! D = 0.733