Topic 4 1 pt 2 http www slideshare

Topic 4. 1 pt 2

http: //www. slideshare. net/gurustip/communities-and-ecosystems

4. 1. U 1 Species are groups of organisms that can potentially interbreed to produce fertile offspring. Species is a group of organisms that can interbreed to produce fertile offspring If species are not closely related it is often impossible for individuals of the different species to breed. If members of two closely related species do interbreed and produce offspring the hybrids will be sterile e. g. mules. https: //i. ytimg. com/vi/8 P 01 Y 6 LDwi 0/maxresdefault. jpg

4. 1. U 2 Members of a species may be reproductively isolated in separate populations. AND 4. 1. U 7 A community is formed by populations of different species living together and interacting with each other. Population is a group of organisms of the same species that are living in the same area at the same time. Organisms of the same species separated geographically or temporally are unlikely to breed, though the ability to do so remains. The separated organisms are regarded as being members of different populations. Community is a group of populations that are living and interacting together in the same area. All organisms are dependent on interactions with members of other species for survival, e. g. a Lion depends on the availability prey species, such as Zebra and Antelope. Communities also include plants and microbes and hence often involve thousands of species. http: //www. adventurewomen. com/wp-content/uploads/2015/04/WPanimals-at-watering-hole-at-Etosha. jpg

4. 1. U 8 A community forms an ecosystem by its interactions with the abiotic environment. nd the a y it n u m m o c e ist of both th s n o c s ndamental m fu te s a y s s a o c h E t n e m n biotic enviro a e h T t. nity that n u e m m m n o o c ir e h T env. s rt nity it suppo u m m o from the c t e n th re n fe o if t d ry e v impac ecosystem is e n u d d n a s a in can exists djacent sea. a e th in y it n u m aquatic com http: //www. slideshare. net/gurustip/communities-and-ecosystems

4. 1. U 11 Ecosystems have the potential to be sustainable over long periods of time. Ecosystems are sustainable Most flows of energy and nutrients in an ecosystem are between members of the biotic community. Relatively few flows of energy and nutrients enter or leave from surrounding ecosystems. Therefore ecosystems are to a large extent self-contained and hence self-sustaining. To remain sustainable an ecosystem requires: • Continuous energy availability, e. g. light from the sun • Nutrient cycling - saprotophs are crucial for continuous provision of nutrients to producers • Recycling of waste – certain by products of metabolism, e. g. ammonia from excretion, are toxic. Decomposing bacteria often fulfill this role by deriving energy as toxic molecules are broken down to, simpler, less toxic molecules. http: //i. dailymail. co. uk/i/pix/2013/01/24/article-2267504 -17212 EB 3000005 DC-781_634 x 663. jpg

4. 1. S 2 Setting up sealed mesocosms to try to establish sustainability. (Practical 5) Mesocosms are biological systems that contains the abiotic and biotic features of an ecosystem but are restricted in size and/or under controlled conditions. The restriction placed on mesocosms make them useful for scientific investigations where the uncontrolled nature of a natural ecosystems makes it difficult to collect meaningful data. The mesocosm in the image has survived for 53 years since being sealed in the bottle: http: //www. dailymail. co. uk/sciencetech/article-2267504/The-sealed-bottle-garden-thriving-40 -years-fresh-air-water. html http: //i. dailymail. co. uk/i/pix/2013/01/24/article-2267504 -17212 EB 3000005 DC-781_634 x 663. jpg

4. 1. S 2 Setting up sealed mesocosms to try to establish sustainability. (Practical 5) Mesocosms are biological systems that contains the abiotic and biotic features of an ecosystem but are restricted in size and/or under controlled conditions. Build your own mesocosm and blog the changes you observe: http: //scribbit. blogspot. com/2010/05/kidssummer-crafts-build-ecosystem. html Learn more about mesocosms developed for research: • The biosphere http: //archive. bio. ed. ac. uk/jdeacon/biosph ere/biosph. htm • Ecotron http: //www 3. imperial. ac. uk/cpb/history/th eecotron http: //i. dailymail. co. uk/i/pix/2013/01/24/article-2267504 -17212 EB 3000005 DC-781_634 x 663. jpg

Quadrat sampling Quadrats are typically a square frame constructed of plastic or pvc pipe, metal rod, or wood that is placed directly on top of the vegetation. • required for estimating several vegetation attributes including: • Density - for counting the number of objects within the unit area of the quadrat. • Biomass - achieved by "clipping" all the material of a given type (e. g. , grass, shrub or forb) or species within a quadrat. • Cover - often accomplished by estimating the area of a quadrat that is covered by a plant's canopy. • Frequency - the proportion of quadrats in which a species occurs is called frequency, thus quadrats are required to estimate plant frequency.

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for associations between species may be associated in different ways Positive association Negative association No association Species found in the same habitat. e. g. predator - prey, herbivore & plant, symbiosis Species occur separately Species occur as in differing habitats. frequently apart as e. g. competitive exclusion, together. require different nutrients

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for the association between two species using the Chisquared test Two continuous belt transects were taken from the edge of a lake to 25 m inland. 1 m 2 quadrats were used making a total sample of 100 quadrats. The presence or absence of two species was recorded for each quadrat: Marsh bedstraw (Galium Bottle sedge (Carex elongatum) is found in ditches rostrata) is a swamp and wet meadows. plant Within the 100 quadrats sampled, 12 contained both bottle sedge and marsh bedstraw, 3 contained only marsh bedstraw, 29 contained only bottle sedge, and 56 contained neither species. Is there an association between the two species? Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx https: //c 1. staticflickr. com/9/8678/15983466342_62 a 12 ba 53 d_b. jpg https: //en. wikipedia. org/wiki/Galium_elongatum#/media/File: Galium_elongatum_e. F. jpg

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for an association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 1 First step in statistics is distribution of two species (i. e. distribution is random) ALWAYS to define the Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) hypotheses Observed values Marsh bedstraw present absent Bottle sedge total present 41 absent 59 total 15 85 2 Complete the contingency table of observed frequencies using the data provided: 100 Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for an association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 1 First step in statistics is distribution of two species (i. e. distribution is random) ALWAYS to define the Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) hypotheses Observed values Marsh bedstraw present absent Bottle sedge total present 12 29 41 absent 3 56 59 15 85 100 total 2 Complete the contingency table of observed frequencies using the data provided: Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for an association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 distribution of two species (i. e. distribution is random) Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) Observed values Marsh bedstraw present absent Bottle sedge total present 12 29 41 absent 3 56 59 15 85 100 total Expected values Marsh bedstraw present absent Bottle sedge total present 41 absent 59 total 15 85 3 Calculate expected values using the formula: = row total x column total grand total n. b. Expected values are what you would expect to be find if there is no association between the species. 100 Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for an association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 distribution of two species (i. e. distribution is random) Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) Observed values Marsh bedstraw present absent Bottle sedge total present 12 29 41 absent 3 56 59 15 85 100 total Expected values Marsh bedstraw present absent Bottle sedge total present 6. 15 34. 85 41 absent 8. 85 50. 15 59 15 85 100 total 3 Calculate expected values using the formula: = row total x column total grand total n. b. Expected values are what you would expect to be find if there is no association between the species. Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for the association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 distribution of two species (i. e. distribution is random) Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) Observed values Marsh bedstraw present absent Bottle sedge total present 12 29 41 absent 3 56 59 15 85 100 total Expected values Marsh bedstraw present absent Bottle sedge total present 6. 15 34. 85 41 absent 8. 85 50. 15 59 15 85 100 total 4 Calculate the Chi-squared value: χ2 50. 15)2 = = (12 – 6. 15)2 + … + (56 – 6. 15 50. 15 = 5. 56 + 3. 86 + 0. 98 + 0. 68 = 11. 10 Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for the association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 distribution of two species (i. e. distribution is random) Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) Observed values Marsh bedstraw present absent Bottle sedge total present 12 29 41 absent 3 56 59 15 85 100 total 4 Calculate the Chi-squared value: χ2 Expected values Marsh bedstraw present absent Bottle sedge total present 6. 15 34. 85 41 absent 8. 85 50. 15 59 15 85 100 total 50. 15 = = (12 – 6. 15)2 + … + (56 – 50. 15)2 6. 15 = 5. 56 + 3. 86 + 0. 98 + 0. 68 = 11. 10 Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx

4. 1. S 3 Testing for association between two species using the chi-squared test with data obtained by quadrat sampling. AND 4. 1. S 4 Recognizing and interpreting statistical significance. Testing for the association between two species using the Chisquared test Null hypothesis (H ): There is no significant difference between the 0 distribution of two species (i. e. distribution is random) Alternative hypothesis (H 1): There is a significant difference between the distribution of species (i. e. species are associated) 6 Compare the χ2 value with the critical values and validate the hypotheses: Critical values for the χ2 distribution df p (% certainty) 1 0. 5 (50%) 0. 455 0. 1 (90%) 2. 706 0. 05 (95%) 3. 841 0. 001 (99%) (99. 9%) 6. 635 10. 827 2 1. 386 4. 605 5. 991 9. 21 13. 815 3 2. 366 6. 251 7. 815 11. 345 16. 268 4 3. 357 7. 779 9. 488 13. 277 18. 465 5 4. 351 9. 236 11. 07 15. 086 20. 517 • It is usual to consider a result statistically significant at the 95% certainty (p <0. 05) level. • As df = 1 that means the H 0 is rejected if X 2 > 3. 841 • Since 11. 10 > 3. 84 H 0 is rejected and H 1 is accepted: there is an association between Marsh bedstraw and Bottle Sedge. n. b. In this case 11. 10 > 10. 827 we can go further and say that we are 99. 9% certain there is an association between the two species. Data from: https: //www. geography-fieldwork. org/ecology/hydrosere/4 -data-analysis. aspx