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POPULATION ECOLOGY BEVOLKINGSEKOLOGIE

POPULATION ECOLOGY BEVOLKINGSEKOLOGIE. REMEMBER THE TERMS. WAT IS ‘N BEVOLKING? What is a population?. Individue van … dieselfde spesie wat in ‘n afgebakende (spesifieke) gebied bly en wat lukraak kan inteel . Individuals of … the same species

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POPULATION ECOLOGY BEVOLKINGSEKOLOGIE

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  1. POPULATION ECOLOGYBEVOLKINGSEKOLOGIE

  2. REMEMBER THE TERMS

  3. WAT IS ‘N BEVOLKING?What is a population? Individue van … • dieselfde spesie wat • in ‘n afgebakende (spesifieke) gebied bly en • watlukraak kan inteel. Individuals of … • the same species • living in a demarcated(specific) areaand • that are able to interbreed randomly.

  4. Examples of populations

  5. Gemeenskappe • Gemeenskappe sluit al die bevolkings van ‘n gebied in bv. Al die springbokke, leeus, doringbome en bosluise in die Kruge Nasionale Park. • Of al die walvisse, haring en plankton in die Noordsee.

  6. Community structureVarious organisms form part of a community

  7. We want to know three things about a population: • Size – how big is the population (how manyare there)? • The densityof the population- how many per unit of habitat/ environment. • The distribution patterns of the individuals in the population. Prickly Pear (Opuntia) an alien invader population in the Karoo-Nama biome

  8. Vier dinamiese parameters beïnvloed die grootte van ‘n bevolking nataliteit Geboorte natality Grootte van bevolking emigrasie immigrasie mortaliteit Sterfte mortality

  9. Factors that influence size of population • Birth – Natality – new individuals that are born into the population. • Death – Mortality – individuals in the population that die. • Immigration – individuals move into the population. • Emigration – individuals leave the population. These are the four dynamic population parameters.

  10. More dynamic parameters • The four dynamic parameters are: natality, mortality, immigration and emigration. • Growth is a parameter for population size if the population is measured in biomass. • Migration plays a seasonal role.

  11. Hoe meet ons die grootte van ‘n bevolking? • DIREKTE METODES: Organismes is groot genoeg en beweeg nie rond nie. ‘n Sensus word geneem – tel bv. Mense of mossels op rotse. • INDIREKTE METODES gee ‘n benaderde syfer. • DIRECT METHODS: Individuals are big enough and do not move a lot. A census is taken- count e.g. people or mussels. • INDIRECT METHODS give an estimated number.

  12. How do we determine the size of a population? 1. DIRECT METHODS – give accurate size of population e.g. counting/ census. Organisms must be ... • big enough • stationary (not moving) or slow-moving • not too many in too big an area

  13. How do we determine the size of a population? 2. INDIRECT METHODS – gives an estimate, not exact number. Can be accurate enough to use in planning, management. • Sampling • Quadrants & transects • Mark-recapture methods (Petersen) • Repeated sweeping • Counting nests or burrows • Calling/singing • Droppings

  14. INDIREKTE METODES • 1. KWADRANTE: • Deel area in aantal ewe groot blokke. • Tel individue in paar van blokke. • Kry gemiddeld en maal met totale aantal blokke. • Benaderde grootte van bevolking. • Veral geskik vir plante.

  15. Gebruik vir bv. klein plantjies, insekte, duisendpote ens.

  16. QUADRANT METHOD USED TO DETERMINE POPULATIONS AND COMMUNITIES ON SEA BED

  17. MARK-AND-RECAPTURE METHOD • Especially suitable for fish in dam. • Catch number of individuals. • Mark and throw back into dam. • Allow to disperse. • Make another catch. • Count number of marked individuals in second catch. • Use the following formula to estimate size of population: P = M x C R or = number of first catch x second catch marked in second catch

  18. Formula for mark-recapture: N = M x C R N = estimated population size M = number of individuals caught and marked in 1st catch C = total number of individuals in 2nd catch R = number of marked individuals in 2nd catch

  19. Formulevirmerk-hervangmetode (Petersen metode) N = M x C R N = verwagte bevolkingsgrootte M = getal individue gevang en gemerk in die 1ste vangs C = totale getal individue in 2e vangs R = getal gemerkte individue in 2e vangs

  20. How could this estimate be improved – made “more accurate”? • Make 3rd and 4th catches. • Use the formula for each of these catches. • Get an average number.

  21. VOORSORGMAATREËLS • Vang op manier wat individue nie seermaak nie. • Merk moet individue nie hinder nie. • Merk moet “permanent” wees m.a.w. moet duur vir tyd van studie. • Laat genoeg tyd tussen vangste sodat individue kan versprei. • Moenie te veel tyd tussen vangste laat sodat geboortes/ sterftes ens. Invloed kan hê nie.

  22. PRECAUTIONS – WHAT TO DO TO ENSURE SUCCESS ... • Catch and handle organisms carefully, don’t hurt them. • Marker should be visible after time e.g. paint in water. • Marker should not hinder organism. • Catches should be timed so that organisms have time to disperse after they were returned to habitat. • Catches should not be too far apart to allow new births to influence results.

  23. VOËLS MET GROOT SORG GERING SODAT HULLE NIE SEERKRY NIE

  24. How do we illustrate population growth? • Two types of growth patterns: 1. Exponential growth (geometric or J-curve). 2. Logistic growth form (sigmoid or S-curve). • Two groeipatrone kom voor: 1. Eksponensiële groei (geometries of J-kurwe). 2. Logistiese groeivorm (sigmoïede of S-kurwe).

  25. WAYS TO PRESENT DATA ON POPULATION GROWTH:

  26. EXPONENTIAL GROWTH

  27. Exponential growth (geometric growth) = J-curve

  28. J-graph indicated by two phases: • 1. LAG PHASE – growth slow, population still small. • 2. EXPONENTIAL PHASE – growth is accelerating. Population can increase dramatically until environmental resistance causes it to crash. Examples: Bacteria, insects, fish (r strategy)

  29. Environmental resistance equilibrium Carrying capacity Decelerating phase Point of inflection Accelerating phase Initial lag phase S-curve

  30. LOGISTIC (SIGMOID) GROWTH: S-curve

  31. FASES VAN ‘N LOGISTIESE GROEIKURWE (S-VORMIG) • SLOERFASE – stadige groei, bevolking klein, moet paringsmaat vind, moet aanpas by omgewing. • TOENEMENDE GROEIFASE (ook genoem die eksponensiële groeifase) – groei maksimum (vinnige tempo) - baie geslagsrype individue wat kan voortplant, oorlewing is hoog. • AFNEMENDE GROEIFASE – groeitempo verminder geleidelik met toename in omgewingsweerstand. • EWEWIGSFASE – bevolkingsgroei stop en kurwe plat af, aantal sterftes = aantal geboortes, bevolkingsgrootte fluktueer rondom dravermoë. K strategy e.g. antelope

  32. Soos wat die digtheid van ‘n bevolking toeneem, neem die omgewingsweerstand ook toe. • Tekorte aan water en voedsel • Shortage of oxygen (especially aquatic populations) • Afwesigheid van lig – in woude (nodig vir fotosintese) • Predators • Parasites • Gebrek aan skuiling • Siektes • Build-up of toxic waste • Tekort aan/ afwesigheid van gebied (territorialiteit) • Sal sterftetempo verhoog of geboortetempo verlaag

  33. DRAVERMOË • Die getalindividuewat die gebiedkanonderhou. • Soosbepaaldeurbeperkendefaktore/ omgewingsweerstand • Geboortes en sterfteskanselleermekaaruit.

  34. CARRYING CAPACITY • The NUMBER of individuals that can be supported by a certain environment/habitat/ecosystem. • Can be different for different species in same area e.g. a meadow can support 15 cows, but 1000 tiny insects. • Carrying capacity determined by environmental resistance: • Amount of food, water available • Shelter • Disease etc.

  35. Wanneer bevolkingsgrootte dravermoë oorskry, word die habitat gedegradeer en dravermoë verlaag.

  36. YOU MUST BE ABLE TO ... • Draw population growth graph from table given. • Identify the type of graph. • Identify different phases. • Explain the trend during each of these phases. • Determine the carrying capacity. • Suggest type of organism that will exhibit similar growth pattern. • Interpret given graph as above.

  37. POPULATION CONTROL • Digtheidsafhanklike faktore: • Digtheid van bevolking bepaal effek bv. Siektes het groter effek in digte bevolking as in yl- verspreide een. • Hoe digter bevolking, hoe groter kans dat faktor kan voorkom bv. voedseltekort. • Density independent factors: • Density of population will not have influence on occurrence of factor e.g. earthquake or tsunami.

  38. Decide whether the following are density dependent or independent factors: predators Viral diseases Tiger marking territory drought

  39. MENSLIKE BEVOLKING

  40. TOTALE GEBOORTESYFER • AANTAL NAKOMELINGE PER DUISEND VROUE • GEBOORTES – STERFTES = BEVOLKING

  41. FAKTORE WAT GEBOORTE EN STERFTESYFERS BEïNVLOED • KULTUUR • EKONOMIE (WAARDE VAN KINDERS) • OUDERDOM VAN VROUE VOOR EERSTELING • VERSTEDELIKING • OPVOEDING • GESINSBEPLANNING • BABASTERFTES

  42. Watter faktore dra by tot groei van menslike bevolking? • Verhoogde voedselproduksie (al het ons gebiede van hongersnood). • Behandeling vir siektes. • Manipulering van tegnologie.

  43. FACTORS INFLUENCING HUMAN POPULATION GROWTH

  44. WAYS TO PRESENT POPULATION COMPOSITION

  45. MENSLIKE BEVOLKINGSGROEI • BEVOLKINGSPIRAMIEDE • HOEKOM IS DAAR MEER VROUENS AS MANS?

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