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Friday, October 19 th : Period E

Friday, October 19 th : Period E. 1. An update on EXCEL 2011 2. Homework Review 2. Completing Topic G.1, Community Ecology. EXCEL – Revised, Improved Worksheet…. Please complete your temperature assignment by Tuesday. The worksheet (revised for EXCEL 2010) is accesible on the Class Blog

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Friday, October 19 th : Period E

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  1. Friday, October 19th: Period E • 1. An update on EXCEL 2011 • 2. Homework Review • 2. Completing Topic G.1, Community Ecology

  2. EXCEL – Revised, Improved Worksheet… • Please complete your temperature assignment by Tuesday. The worksheet (revised for EXCEL 2010) is accesible on the Class Blog • Please contact me if you don’t have access to EXCEL, or if you need some help • Use your IB Independent Assessment Guide – it has all of the answers to your questions!! • Online help: • Getting started with EXCEL

  3. Homework Review: Factors Affecting Plant and Animal Species Distribution

  4. i-Biology Link

  5. i-biology hyperlink

  6. Homework Review: Relationships Between Species

  7. Relationships Between Species

  8. Let’s Check those relationships… • It's David....(3.30) • National Geographic Anemones/clownfish • PBS marine interactions • Marine Mutualism

  9. COMPLETING Topic G:1 • Competition! • The niche concept • Competitive exclusion • Niche partitioning

  10. ‘Competition’ in Ecology? When does it happen? • Shared resource in short supply • Competion is a density dependent determinant of population dynamics Do competitors have to meet each other? Competition can be between individuals of the same species (intra-specific) or between different species (inter-specific)

  11. Intra-specific competition: Competition for mates • Male Bighorn Sheep • Bisons headbutting

  12. Intra-specific competition: Darwin’s Finches • Darwin's Finches

  13. Interspecific Competition Competition between different species which depend on the same resource: • Food • Water • Nesting Sites • Breeding Sites Examples: Competition...in spades...

  14. The Niche Concept Topic G.1.5: Explain what is meant by the niche concept, including an organism’s spatial habitat, its feeding activities and its interactions with other species

  15. The Niche Concept: Definition ‘Nicher’ (French): to Nest • A term describing the way of life of a population • To describe a population’s niche, you need to describe its ‘specialised habitat’: • space and territory • Nutrition and feeding habits • Interactions with other organisms • Its reproductive habits • Its role in the community

  16. The Niche concept: A Working Analogy In 1927, Charles Sutherland Elton, the British Ecologist, stated: ‘When an ecologist states ‘There goes a badger’, he should include in his thoughts a definite idea of the animal’s role in the community, just as if he had said ‘There goes the vicar’

  17. Defining a Niche : ‘The Boundary conditions’ Two species that use exactly the same resources cannot occupy the same niche Only one species or population can occupy the same niche for an extended period

  18. G.1.8: Distinguish between fundamental and realized niches.

  19. Fundamental Niche A species’ fundamental niche is the full range of environmental and social conditions under which it could potentially survive and reproduce ‘potential niche’ • Some species have a broad fundamental niche • Some species have a narrow fundamental niche

  20. Realised Niche The realised niche is the specific set of conditions in which it survives in a given habitat or ecosystem, given the other species or limitations present. These are the conditions to which the population is best adapted.

  21. ‘Realised Niche’ is not a constant for a species • In fact, populations of the same species may occupy different realised niches within different ecosystems • It all depends on the other species and environmental factors involved in ‘sharing of the resources’

  22. Let’s look at some examples….

  23. G.F. Hutchinson’s Definition of the Hyperdimensional Niche…

  24. Homework for Monday • Research information for two species of your choice. • One can be the Clown-fish • The other can come from the WWF website: • WWF species directory

  25. G.1.7: Explain the principle of competitive exclusion Aka ‘Gause’s Law’ ‘No two species can occupy the same niche for a prolonged time’

  26. The Competitive Exclusion Principle • If two species share a niche, there must be inter-specific competition for resources • The best adapted species will survive • The loser will struggle to survive and reproduce, and will eventually become extinct OR migrate (if its niche is broad enough) Examples are abundant • Invasive species • Red versus Grey Squirrel in Western Europe • Gause’s Paramecium

  27. Competitive Exclusion: Squirrels

  28. Competitive Exclusion: Squirrel Distribution

  29. G.1.7: Outline the method and importance of G.F. Gause’s paramecium experiments Gause's Struggle for existence can be accessed in full online (even in Russian!)!

  30. G.1.7: Outline the method and importance of G.F. Gause’s paramecium experiments GeorgyGause cultured 2 species of the protistParamecium: • P. Aurelia • P. Caudatum • Grown together under ideal conditions, both populations reach a higher maximum • Grown together, one species rapidly becomes extinct…

  31. Let’s think about it…..How does environmental change affect a species with a broad niche?

  32. Species with a broad niche • ‘Generalists’ • Widely distributed geographically • Adaptable Red-Tailed Hawk

  33. Let’s think about it…..How does environmental change affect a species with a narrow niche?

  34. Species with a narrow Niche • ‘Specialists’ • Not adaptable • Under threat of extinction if the niche changes

  35. Does Competitive Exclusion work in the real world?.... The competitive Exclusion principle is actually rarely observed in natural ecosystems: • ‘spatial heterogenity’ (niche partitioning) • Niche sharing/ partitioning associated with availability of multiple resources • ‘The paradox of the plankton’: Why do so many plankton species exist in a small, limited, homogenous habitat?

  36. Niche Partitioning As there is a limited about of space and resources on Earth, organisms can use niche partitioning 1. Spatial: Two different species use the same resource by occupying different areas within the range of the resource 2. Temporal: Two species eliminate direct competition by using the same resource at different times 3. Morphological: Two different species evolve different morphologies in order to use a resource in different ways

  37. Spatial Niche Partitioning Closely related bird species occupy different foraging locations on a single tree species

  38. Temporal Niche Partitioning Different species of spiny mouse inhabiting the same ecosystem may be either nocturnal OR diurnal feeders

  39. Morphological Niche Partitioning Different beak sizes have allowed adaptive radiation of finches in the Galapagos Islands

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