OPTION G

1. OPTION G G 1, G 2, G 3 SL TOPICS

2. G1 Community ecology Abiotic factors that effect distribution of plant species Discuss how each factor affects plants species • Temperature (determines plant communities, desert plants show specific adaptations) Why does temperature affect plants distribution? • Water (determines plants species desert plants?) Why does water determine plants species in an ecosystem? • Light Why does light affect plants distribution? • Soil pH How does pH of soil and water affect plants? Acid rain? • Salinity Effect of salt on plants? Link osmosis. Halophytes live in salt marshes. • Minerals Why are minerals important for plants? pH and mineral uptake relationship?

3. Discuss how each factor affects animals species • Temperature: How does temperature affect animals distribution? Cold blooded and warm blooded animals? Thermoregulation adaptations? • Water Animals adaptation to desert? For habitat or reproduction • Breeding sites Many animals need special breeding sites. Salmon • Food supply Many animals have special diet. Humming birds eat nectar. Panda bears? • Territory Some animals need special territory. Ex. Tigers

4. Ecological Sampling • What is a sample? • “A portion, piece, or segment that is representative of a whole” • Why do we sample? • it is usually impossible to measure the whole

5. One big assumption… • That the sample is representative of the whole • It is necessary to take enough samples so that an accurate representation is obtained • It is important to avoid bias when sampling

6. Sampling Methods • Transects and Quadrants • Plants and Non-motile animals • Lincoln Index • Capture –Mark- Recapture • Small animals • Aerial observations • Large trees and animals

7. Sampling along Transects • Samples taken at fixed intervals • Set up along an environmental gradient (e.g. high to low on a mountain)

8. Line transect method • A measured line laid across the area in the direction of the environmental gradient • All species touching the line are be recorded along the whole length of the line or at specific points along the line • Measures presence or absence of species

9. Belt transect method • Transect line is laid out and a quadrant is placed at each survey interval • Samples are identified and abundance is estimated • Animals are collected • For plants an percent coverage is estimated • Data collection should be completed by an individual as estimates can vary person to person

10. Quadrats • Used to measure coverage and abundance of plants or animals • A grid of known size is laid out and all the organisms within each square are counted.

11. Lincoln Index • Capture-Mark-Recapture • Animals are captured,counted, tagged and released. • After a period of time another capture occurs. • Previously tagged animals are counted and unmarked organisms are marked. • Abundance is calculated using the following formula:

12. Measurements • Sampling methods measure • Density • Coverage • Frequency • Biomass • Diversity

13. Density (D) • The number of individuals per unit area • D=ni/A • Eg. 10 dandelions/m2 • Relative density i (Rdi) • The Density of species i, Di, Divided by the sum of all the densities of the other species sampled • Rdi=Di/SD • Eg. 10/5+8+16

14. Coverage (C) • The proportion of ground that is occupied or area covered by the plant/species • Ci=ai/A • Relative coverage • The Coverage of species 1, Ci, divided by the sum total of the coverage of the other species sampled

15. Frequency (f) • The number of times a given event occurs • Eg. the number of quadrants that contain maple trees as a ration of all the quadrants • fi=ji/k • Relative frequency • The frequency of species i relative to the sum total of the frequencies of the other species found

16. Biomass (B) • Can be calculated by measuring the mass of the individuals per unit area • B= SW/A • More appropriate measure than density or frequency when • Number of individuals in hard to determine • Photosynthesis and carbon fixation, energy and nutrient transfer are more dependent upon biomass than the total number of individuals

17. Biomass Measurement methods • Fresh or wet weight • Used when organisms are alive • Dry weight • Used when the water content varies greatly • Oven dry at 105oC to remove water • Ash-Free Weight • Used when inorganic content varies greatly • Oxidize at 500oC until only inorganic ash remains

18. Diversity • The measure of variety of an ecosystem • Consists of 2 components • The number of different species or the richness of species in a specific area • The relative abundance of the individuals of each species in a specific area

19. Simpson's Diversity (D) • Measures species richness • If D is high the area may be a stable ancient site. • Low D may suggest pollution, recent colonization, or agricultural management

20. Random sampling and quadrat methods,See the worksheet • Use of a transect • See the worksheet

21. INTERACTION BETWEEN BIOTIC FACTORS 1- Symbiosis a. Mutualism b. Commensalism c. Parasitism 2- Competition 3- Feeding relationship a. herbivory (grazing) b. predation

22. Symbiosis: is a long term interaction between two species which live in or on.. • Mutualism describes any relationship between individuals of different species where both individuals benefit. • lichen: algae and fungi, legumes and nitrogen fixation bacteria • anemone hermit crab

23. Mutualism: Lichen

24. Lichen

25. Commensalism • Commensalism describes a relationship between two living organisms where one benefits and the other is not significantly harmed or helped.

26. Commensalism

27. Barnacles adhering to the skin of a whale or shell of a mollusk

28. Parasitism • A parasitic relationship is one in which one member of the association benefits while the other is harmed

29. Feeding relationship • Producers: produce organic molecules by photosynthesis or chemosynthesis • Consumers: feed on other organisms. • Herbivores: eat plants. They are primary consumers • Carnivores: they eat meat. They can be secondary, tertiary consumers. • Omnivores: they eat both meat and plant.

30. ScavengersIt is a carnivorous feeding behaviour in which a predator consumes corpses that were killed by by other animals. It is part of decomposition.Well known scavengers include vultures, burying beetles, blowflies, yellowjackets, and raccoons Detritivores: Animals which primarily consume dead plants. Organisms such as termits, worms in soil are examples. Decomposers: fungi and bacteria that obtain their nutrients and energy mainly by feeding on dead organisms by digesting them outside of the cell.

32. Feeding relationship

33. Prey- predation

34. Competition Interspecific competition: Competition between two different species. Why?

35. Intraspecific competition: competition between the members of the same species. • Why do they compete?

36. WHAT IS NICHE? NICHE describes; • where the organism lives • how it lives • how it interacts with other member of the community

37. Fundamental and Realized Niches Fundamental niche: is the niche that an organism could potentially occupy. Realized niches: is the proportion of the fundamental niche that actually occupied by the organisms. In other words it is the actual mode of existence, which results from its adaptations and competition with other species.

38. The Competitive Exclusion PrincipleKEY POINTS • For any given species a niche is precise and cannot be occupied by more than one species. • When the niches of two different species overlap, competition takes place for the resources. • The stronger species exclude the weaker one

40. Parasitism: ectoparasite sheep thickMutualism : Fungus takes sugar and amino acids from root and it gives ions to the root

41. Biomass Biomass is the total weight (or volume, or energy equivalent) of living organisms in a given area (e.g. a quadrat). (kJ m−2 yr−1).

42. Productivity of an ecosystem • Primary productivity, the production of new organic matter by green plants (autotrophs) 6CO2 + 12H2O ----------- C6H12O6 + 6H2O +6O2 Photosynthesis • Secondary productivity, the production of new organic matter by consumers (heterotrophs).

43. Both primary and secondary productivity can be divided into gross productivity and net productivity. 1- Gross productivity is the total gain in organic matter (biomass) or energy per unit area per unit time. 2- Net productivity is the gain in energy or biomass per unit area per unit time that remains after deduction due to respiration. Gross production – respiration = net production.

44. Calculate W,X,Y and Z 2.00 x 107 360,000 1.96 x 107 400,000

45. So how are gross and net productivity related ? Net productivity = Gross productivity - Respiration Energy or using symbols: NP = GP - R This equation applies to animals too, but more on that later….. The productivity of a plant is called: PRIMARY PRODUCTIVITY because plants are the first or primary organisms in the food web

46. So what about animal productivity? • Animals must eat other organisms to obtain energy, unlike plants which photosynthesize • Animals may eat plants or animals or both • Not all the energy in food is absorbed (assimilated) into an animal’s body • Unassimilated food is ejected as faeces or droppings So gross productivity = food assimilated or gross productivity = food eaten - energy in faeces

47. What about net productivity for an animal (secondary consumer)? • Gross secondary productivity = Energy in eaten food - energy in faeces • As well as keeping themselves alive, animals must use energy to move and keep warm - plants need rather less energy- but in the end it, as in plants, it all turns to heat • Net secondary productivity (NSP ) = food eaten - faeces - respiration energy so NSP = GSP- R (just like plants) ?

48. NPP versus NSP

49. PRODUCTIVITY OF ECOSYSTEMS

50. The following data were collected in a study of secondary productivity in a population of woodlice. Some of the woodlice produced offspring during the experiment. Source: IB Examination Paper 1 May01