2. POPULATION SIZE Terminology:  Species: a group of organisms which share the same characteristics and are capable of interbreeding to produce fertile offspring.  Population: a group of organisms of the same species which live in the same habitat so that random interbreeding takes place  Community: populations of different species living and interacting in the same habitat.  Ecosystem: The living community and their interactions with the abiotic component  Population ecology- The study of the changes in population size and their causes.

4. The relationship between species, populations community and the ecosystem

5. Population size is affected by:  Inborn factors  Environmental changes

6. Population size Emigration Mortality (Death rate) Immigration Natality (Birth rate)

7.  Natality : the birth rate. It’s the production of new individuals by birth, hatching, germination or division. POPULATION PARAMETERS

8. Natality strategies R-STRATEGY  Many offspring  Low parental care and low chances of survival  Typical of pioneer species  e.g. ? K-STRATEGY  Few offspring  High amount of parental care and survival  Usually climax species.  e.g. ?

10. Human natality Fertility rate- no. of births per 1000 females of child-bearing age per year. Fecundity rate- Average number of children born in one generation per female of child- bearing age.

11. Mortality - death rate

12. SURVIVORSHIP CURVES PG 272-273

13. Complete metamorphosis: 4 stages: egg, larva, pupa, and adult e.g. _______larvapupa Incomplete metamorphosis: 3 stages: egg, nymph and adult. e.g.___________

14. Complete metamorphosis is characteristic of beetles, butterflies and moths, flies, and wasps. Their life cycle includes four stages: egg, larva, pupa, and adult. The larva differs greatly from the adult. It is wingless, and its form and habits are suited for growth and development rather than reproductionlarvapupa

15. Dispersal - movement of individuals, or parts of individuals, from one habitat to another - immigration, emigration and migration together are called dispersion

16. Immigration : the process that occurs when an organism enter a new place to settle permanently Emigration - the process that occurs when an organism leaves one place to go and live in another place permanently Migration - animals move from one area to another because of lack of water, food or to avoid winter temporarily

17. Migration of zebra and wildebeest in the Serengeti

18. Wildebeest migration: migration is a response to seasonal change. The function of migration is to keep animals in a suitable environment throughout the year.

19. Migration of birds: If habitat quality declines, animals improve their chances of survival and reproduction by going elsewhere

20. Effects of dispersal are affected by: Population density and Time between movements (rate)

21. ACT 3.1.1 pg 274

22. Population fluctuation and regulation  CARRYING CAPACITY- The maximum population size which the environment can accommodate. (can vary)  POPULATION REGULATION- tendency of a population to return to the equilibrium size  POPULATION STABILITY- tendency of a population to remain at a constant size.

23. Population size is limited by: density-dependent factors density-dependent factors  Competition  Predators  Food  Crowding  Disease  Parasites › The greater the population, the greater effect these factors have. density-independent factors › Volcanic eruptions › Temperature › Storms › Floods › Drought › Chemical pesticides  Most are abiotic factors

24. POPULATION GROWTH FORM  GEOMETRIC GROWTH FORM (J-shaped curve) LAG PHASE ( Population is getting accustomed to new environment) (GEOMETRIC/LOG)/ACCELERATED GROWTH PHASE (Rapid growth) Time Population size

25. Time Number of indivuals – population size Graph to show a geometric (J-shaped) growth form Lag phase Accelerating growth phase Repetition in mosquitoes (summer growth, winter death phase)

26. LOGISTIC GROWTH FORM (S-shaped curve) Accelerated growth Population size

27. Time Number of indivuals – population size Carrying capacity Lag phase Accelerating growth phase Decelerating growth phase Equilibrium phase (stationary phase) Environmental resistance Graph to show a logistic (S-shaped) growth form © Lizette Neethling 0828246343

28. ALag phaseSEE PG 279 T/BOOK First phase Population grows slowly, because the organism is getting accustomed to the new environment BAccelerating, geometric or logarithmic growth phase Second phase Population size increases rapidly Little or no limiting factors CDecelerating growth phase Third phase Environmental resistance begins to play a role DEquilibrium phase or stationary phase Usually final phase Reach carrying capacity Environmental resistance occurs EDeath phase (not always present) Occurs sometimes as a last phase Can be result of drought, diseases, accumulation of waste etc Population size drops Time Population size A B CDE

29. ACTIVTIY 3.1.2 pg 280 PART A- Classwork/homework

30. A  1. Logistic growth  2 A- lag phase B- accelerating growth phase D- Equilibrium/ stationary phase 3. Organisms are still getting used to the environment 4. B 5. A- part C B- part D C- part B.6. Climate change, availability of food, space, shelter, predators

31. DETERMINING POPULATION SIZE Direct technique (census – counting individuals)

32.  AERIAL PHOTOGRAPHY

33. The direct method – best for slow moving organisms

34. INDIRECT TECHNIQUES MARK-RECAPTURE A nimals are caught, marked and then released to mix thoroughly with the unmarked individuals of the same species. Later, a second sample is taken and the number of marked and unmarked animals is counted.

35. P = No. marked initially X No. in 2 nd sample ---------------------------------------------------------- No. marked in 2nd sample SEE e.g. pg 282 Indirect technique –mark and recapture

36. Mark-recapture mini prac Trial noNo 1 st marked No. in 2 nd sample No. marked in 2 nd sample Estimated population size 1 2 3 ACTUAL NOAVERAGE

37. RELIABILITY  repeated several times and calculate the average VALIDITY  Only a short time should pass between the samplings (no births and deaths should occur)  The marking must not damage the individual  Marking must not affect movement or behaviour  The marked animal must mix freely with the rest of the population  No immigration or emigration is allowed, (closed population) © Lizette Neethling 0828246343 Improving reliability and validity of results

38. ACTIVITY 3.1.4 pg 284 No 1 only  1.2 the area sample might be one that grasshoppers preferred / did not prefer.  Some grasshoppers may have emigrated/immigrated  Some grasshoppers may have died.  1.3 sample areas must be taken randomly  Repeating the process many times and finding the average estimate

39. SIMPLE SAMPLING Make a physical count of all the animals/plants under investigation in a small sample area of the habitat and calculate the total population using the formula =x=x Total no. in population No. in sample Habitat size sample size

40. This method is useful in sampling plants and sessile or slow-moving organisms Choose your samples randomly Take several samples and take the average estimate

41. Random sampling: a sample that is not deliberately selected but is selected by chance. This means that any area being sampled or any individual in a population being sampled has an equal probability of being selected

42. Quadrat sampling method for plants

43. ACTIVITY 3.1.6 PG 287  For the counting, those that are in the block or half or more in are counted as being in.