1. Populations and Communities

2. Activity 37 pg

3. Studying Populations
Population= all living things e.g. Frogs in local pond, balsam firs in local forest.
Must all be same species, in shared space.
Shows how species evolve.

4. Population Size Number individuals it contains
Varies with time due to births, deaths, immigration, emigration

5. Births + immigration vs. Deaths + emigration
 = population incr.
 = population decr.
= = stable

6. PG. 310 Q 1-4

7. Measuring a Population
1) Counting Individuals- count ALL individuals in certain area
2) Count by sample Area- counting individuals in randomly selected areas called quadrants
Pop. Size = Avg. # per section x total study area
Area of selection

8. 3) Mark and Recapture- to estimate size of mobile animals e.g. Birds
Pop. size = # marked x total # captured 2nd time
# marked animals recaptured

9. Activity 38 pg

10. Population Density The average # within given area
Density will vary with habitat (food, water, climate, predators, disease etc.)
Population density = # individuals
area or volume occupied

12. Pg Q5-9

13. Population Distribution
1) clumped = groups- when certain areas of habitat = better living conditions e.g. Herds

14. Population Distribution
2) uniform = distributed evenly- when fighting for resources e.g. Territory

15. Population Distribution
3) random = no pattern- because cannot clump or spread out e.g. plants

16. McDonald’s Restaurants
Random
Clumped

17. Ecological Factors
Abiotic- non living factors- physical or chemical aspects e.g. pH of water
Biotic- living factors- food source, predators
Intensity of factor determines effect on population

18. Limiting Factors If it reduces or prevents growth
1) if absent from habitat e.g. Sunlight cut off to plant = no photosynthesis
2) in excess e.g. Too much rain = roots of plant rots
3) if insufficient quantities e.g. Frogs get disease so less, snake population will be affected

19. Biological Cycles Populations have periods of growth and decline
Populations of food source and predators are very closely related

20. Pg Q 10-15

21. Activity 39 pg

22. Studying Communities

23. Biodiversity
Recording of all the types and numbers of species living in a community
Species richness = # species in a community e.g. # blonde grade 10 girls at C.V.R.
Relative abundance = # each species in relation to total # individuals in the community e.g. # blonde grade 10 girls compared to the total population of C.V.R.

24. Interaction Between Individuals in a Community
Individuals do not live in isolation:
1) Competition: certain resources are limited
E.g. Food source, water source
Intraspecific- competition between same species
Interspecific- competition between different species

25. 2) Predation- one organism feeding off another
Deer eating grass, lioness hunting a gazelle
Predator feeds off another
Prey is the food
Parasites = takes food from host
Host supplies the food

26. 3) Mutualism- interaction benefits both species.
- anemone and clown fish- fish acts as bait to anemone's food, anemone's sting protects clown fish

27. 4) Commensalism- benefits one without affecting another
Bird build s nest in a tree

28. Effect of interactions between populations and their densities
Type of interaction
Effect on population A
Effect on population B
Competition -
Predation and Parasitism +
Mutualism
Commensalism

29. Pg Q 16-19, A-C