1. Characteristics of Populations

2. The Tale of Easter Island
3000 Km off the coast of Chile
5th century – 400 people
Created Moai…had food and war was unknown
Several centuries later…15000!
Not enough food…rats introduced…
destroyed the forest!
Video clip - Attenborough Explains Easter Island

3. What can be learned from this?
ARE YOU READY…PAGE 646!!

4. Population Terms… Habitat: place where organisms/species normally live
Species: Organisms that resemble one another in chemistry, appearance, behaviour, and genetic makeup, which have the ability to interbreed with each other to produce fertile offspring

5. Population Terms…
Population size: refers to the number of individuals of a particular species that occupy a given area or volume at a given time
Population Density: refers to the number of individuals of the same species that occur per unit area or volume.

6. Calculating Pop. Density
D = Population Density
N = total numbers counted
S = space occupied by population 
Example: 600 deer living in 620 hectare region of a conservation park would be calculated as follows…

7. Calculating Pop. Density
Small organisms usually have higher population densities than larger organisms
Population density can be difficult to establish due to unusable space within a habitat, so ecologists use two different forms of calculations…

8. Crude Density: the number of individuals of the same species per total unit area or volume
Ecological Density: number of individuals of the same species per unit area or volume actually used by the individuals.

9. Environmental conditions differ throughout a population’s geographic range causing population dispersion of organisms within a population to vary throughout the range!

10. Population Dispersion
Is the general pattern in which individuals are distributed through a specific area
3 main dispersion patters in wild populations
clumped (most common – organisms densely grouped in areas of habitat with favourable conditions)
uniform (individuals evenly distributed throughout habitat)
random (individuals minimally influenced by interactions with other individuals; habitat conditions virtually uniform)

12. Measuring Populations
Most populations are dynamic
Numbers and geographic locations change over time
Sample of the population used to estimate population size and density using variety of sampling techniques
Why Measure?
Conservation strategies, harvest rates etc

13. Measuring Populations
Quadrat is a sampling frame used for estimating population size for large areas.
number of individuals counted within each quadrat
total population size estimated via calculations within a representative area
most effective for stationary species
Page 654…

14. Quadrat Sampling

15. Mark-Recapture Method
Used for mobile populations
Sample of animal captured, marked, released,
After time to allow animals to mix randomly with unmarked animals in populations, second sample captured
Marked to unmarked in second sample used to estimate size of entire population
M (Total Marked) = m (# of recaptures)
N (Total Pop) n (size of recap sample)
N = Mn m

16. N = Mn m
N=?
M=26
n = 21
m = 3
N = 26 x 21 3
N = 182

17. What is the Grade 12 Population?
Mark-Recapture Demo
Page 567

18. Technological Tracking of Wild Populations
sample of animal captured, marked with radio collars, satellite-linked devices, etc.
animals tracked for their migration and behaviour patterns across their geographic range
Ethics…
CCAC…Reduce, Refine, Replace

19. Homework…You Know You Love it!
Page 651 # 1-3
Page 654 # 4
Page 657 # 5
Page 659 #1-7