Ecological Niche

1. Ecological Niche

2. Ecological niche • Niche = an organism’s role or way of life in a community. Depends on the adaptive features, and the habitat of the organism. (Kind of like the organism’s ‘job’)

3. Gause’s Principle • I want you to just take brief notes about all this information! • Gause – Russian biologist who studied the interactions between 2 species of protist. • Put both species in a test tube and then after a while only one species remained. • Which species survived depended on the conditions in the tube – he concluded that • “No two species can occupy the same ecological niche in the same habitat for an indefinite period”

4. Character displacement • Competition will be high if the two species’ habitats overlap.

5. Character displacement • Competition will be high if the two species’ habitats overlap. • However, is can be reduced by character displacement – a characteristic that is different on one species.

6. Character displacement • Competition will be high if the two species’ habitats overlap. • Comp. can be reduced by character displacement – a characteristic that is different on one species. • This enables the two species to co-exist.

7. Ecological equivilents • Organisms that are evolutionarily different but share similar niches. • EG.

8. Population • Group of individuals of the same species living in one area at one particular time.

9. Population

10. Measuring population • Difficult to count WHOLE populations, so a sample is taken.

11. Measuring population • Difficult to count WHOLE populations, so a sample is taken. • Sample is usually random, so can represent the typical population.

12. Measuring population • Difficult to count WHOLE populations, so a sample is taken. • Sample is usually random, so can represent the typical population. • To measure the size of a population in mobile organisms, mark-recapture techniques are used – capture, label, release.

13. Measuring population • Difficult to count WHOLE populations, so a sample is taken. • Sample is usually random, so can represent the typical population. • To measure the size of a population in mobile organisms, mark-recapture techniques are used – capture, label, release. • Size of population = total number in 1st sample x total number in 2nd sample number of marked animals recaptured in second sample

14. Using the population equation • 60 stoats are caught and released. 3 months later, 25 stoats are captured, 14 of which have already been tagged. Size of stoat population = 2. 25 blue ducks are tagged. 1 month later 20 are captured, and 12 of them already have tags. Size of blue duck population =

15. Transects • Line placed across a habitat.

16. Transects • Line placed across a habitat. • Transect is divided into intervals and at each interval the population is sampled.

17. Transects • Line placed across a habitat. • Transect is divided into intervals and at each interval the population is sampled. • Used when species are affected by environmental factor (Eg. Trampling of plants on lawn affecting their distribution)

18. Quadrats • Square frame used to isolate area so number of organisms can be counted.

19. Quadrats • Square frame used to isolate area so number of organisms can be counted. • Often used where organisms cannot move.

20. Quadrats • Square frame used to isolate area so number of organisms can be counted. • Often used where organisms cannot move.

21. Instructions.