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DEMOGRAPHIC TRANSITION

DEMOGRAPHIC TRANSITION. Way to explain changes in population composition e.g. high to low birth rate. FOUR STAGES: STAGE ONE: Both death and birth rate high ( pre-industrial ). Balance in population. DEMOGRAPHIC TRANSITION STAGE TWO:. DEVELOPING COUNTRIES

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DEMOGRAPHIC TRANSITION

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  1. DEMOGRAPHIC TRANSITION Way to explain changes in population composition e.g. high to low birth rate. FOUR STAGES: STAGE ONE: Both death and birth rate high (pre-industrial). Balance in population.

  2. DEMOGRAPHIC TRANSITION STAGE TWO: DEVELOPING COUNTRIES Death rates drop dramatically – better food and sanitation, less disease. Better education, healthcare, access to technology, better farming techniques. Birth rates continue to be high. Increase in population occurs, pressure on economy, health care, education etc.

  3. DEMOGRAPHIC TRANSITIONSTAGE THREE: DEVELOPING TO DEVELOPED COUNTRIES Birth rates fall – contraception, higher wages, urbanisation, decrease in subsistence agriculture, increase in education and status of women, children don’t work, parents invest in children’s education. Population growth begins to level off.

  4. DEMOGRAPHIC TRANSITIONSTAGE FOUR: DEVELOPED COUNTRIES Low birth rates, low death rates. Birth rate may drop to below replacement level (Germany, Italy, Japan). Death rate may increase due to lifestyle diseases and ageing population. Threat to industries relying on population growth. Economic burden on shrinking working population.

  5. Factors that can cause a decrease in population growth • Diseases such as HIV/AIDS, bird flu, H1N1 etc. • Better living conditions and better education leading to better family planning. • Better contraceptives. • Wars. • Natural disasters. Kaposi sarcoma, a skin cancer typical of HIV/AIDS

  6. Factors that influence community structure • Predasie • Kompetisie • Kompeterende uitsluiting • Hulpbronafbakening • Simbiose • Suksessie • Predation • Competition • Competitive exclusion • Resource partitioning • Symbiosis • Succession

  7. PREDATOR-PREY-RELATIONSHIP

  8. PREDASIE

  9. PREDATOR-PREY RELATIONSHIP • Direct link between predator and prey numbers. • As prey increase, there will be more food for predators, so will predators increase. • Increase in predator numbers put pressure on prey numbers. Prey will decrease. • Decrease in prey will mean less food for predators, numbers will decrease etc.

  10. ROL VAN KOMPETISIE • Kompeteer om dieselfde, maar beperkte bronne bv. Water, lig, voedsel, gebied, paarmaat. • Intraspesifiek – dieselfde spesie. • Interspesifiek- verskillende spesies. Hyena and lion Intraspecific or interspecific? Explain your choice

  11. Competition1. Intraspecific competition: the competition between organisms of the same species depending on the same resources like food, space, shelter, water and access to mates.

  12. Competition2. Interspecific competition: the competition between organisms of different species depending on the same resources e.g. light, space, water, shelter, food

  13. COMPETITIVE EXCLUSION: The competition in which one of the two competing species is much more successful that the other, to such an extent that the successful species survives and the other species disappears.Kompeterendeuitsluiting: Een van die spesies is ‘n baiebeterkompeteerder; wanneerhysaam met ‘n anderspesie in diese3lfde habitat is, salhyoorleef en die anderuitsterf.

  14. Competitive exclusion Wie is die beter kompeteerder?

  15. RESOURCE PARTITIONING: The kind of competition situation in which competing species coexist in the same habitat since they use the resources slightly differently.HULPBRONAFBAKENING:Kompeterendespesieskansaambestaan en oorleefomdathullebronne op verskillendemanierebenut.

  16. Resource partitioning amongst plants

  17. Resource partitioning: co-existing shore birds

  18. Wat is simbiose? • Simbiosebetekenletterlik “saamleef” – sym = saam, en bio = lewe. • Die saamleefverhouding is gewoonliklewensbelangrikvir ten minsteeen van die partye. • Dit is ‘n langtermynsaamleef en nietoevallig of tydeliknie.

  19. MUTUALISME • Tot voordeel van beide partye. • Geen party word benadeel nie. • Voorbeeld: vlinder en blom – blom word bestuif, vlinder kry nektar.

  20. Verpligtemutualisme • Die saamleef-verhouding is lewensbelangrik vir albei partye. • Ligene (korsmosse) – swamme verskaf blyplek en absorbeer water; alge fotosinteer en verskaf voedsel.

  21. Nie-verpligte mutualisme • Die saamleef-verhouding is steeds belangrik,maar nie noodwendig tussen twee spesifieke individue nie bv. Die vlinder en blom (reeds genoem). • Die bosluisvoël kry voedsel en die wildsbok is vry van parasiete.

  22. KOMMENSALISME • Die een party word bevoordeel – die ander party word nie bevoordeel of benadeel nie bv. Beesryer wat hier ‘n saamry-geleentheid kry, maar goggas op grond vreet waar bees vroetel.

  23. Nog kommensalisme … • Die remora-suigvis gebruik die haai as ‘n taxi en vreet van die afvalstukkies voedsel wanneer die haai vreet. SUIER AAN BO-KANT VAN REMORA

  24. PARASITISME • Een party word bevoordeel, die ander word beslis benadeel. • Parasiete wat op diere teer (en self diere is), kan ektoparasiete of endoparasiete wees.

  25. Plantparasiete • Semi-parasiete is slegs vir water en minerale van die gasheer afhanklik en kan self fotosinteer bv. voëlent (Viscum). • Holoparasiete is geheel en al afhanklik van die gasheer en bevat geen chlorofil nie bv. Dodder.

  26. Community change over time: Ecological succession TERMINOLOGY IMPORTANT 3. Secondary succession: the sequence of organisms that occupy a disturbed habitat or when an established community has been disturbed in a catastrophic manner. 4. Climax community: the final stage in the process of succession that refers to a mature community of plants that will remain stable with few, if any, changes over time 1. Primary succession: the sequence of organisms that occupy a new habitat. 2. Pioneer plant: a plant that can colonise bare soil and that is part of the community that forms the first stage in the process of succession

  27. The gradual replacement of one plant community by another through natural processes over time

  28. Succession

  29. colonization of new sites by communities of organisms – takes place on bare rock

  30. New bare rock comes from 2 sources: • 1. volcanic lava flow cools and forms rock

  31. New bare rock comes from 2 sources: 2. Glaciers retreat and expose rock; ALSO FLOODS AND LANDSLIDES

  32. the first organisms to colonize a newsite E.g.: lichens are the first to colonize lava rocks

  33. As lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

  34. Simple plants like mosses and ferns can grow in the new soil The simple plants die, adding more organic material. The soil layer thickens, and …..

  35. … grasses, wildflowers and other plants begin to take over plantecology.wordpress.com

  36. Shrubs and trees can survive now

  37. Waareenskaal rots was, is daarnou ‘n florerendegemeenskap.

  38. Primary Succession- Rock

  39. Begins in a place that ALREADY has soil and was once the home of living organisms • Occurs faster and has DIFFERENT pioneer species than primary succession.

  40. Example: • After a forest fire • Or when a farmer plows his field

  41. a stable, mature community that undergoes little or no succession

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