1. Pyramids

2. Population Pyramids
Show members by sex and age.

5. The autotrophs (“self feeders”) are the primary producers, and are usually photosynthetic (plants or algae).
They use light energy to synthesize sugars and other organic compounds.
Heterotrophs (“other feeders”) – can’t make own food

7. Pyramid of Productivity
These show productivity of organisms at different trophic levels, which depends on:
the energy available from the previous trophic level
the efficiency of the organisms
Unit = joules

9. Pyramid of Numbers
The information collected for each trophic level is the total number of organisms in the area, which depends on:
the size of individual organisms
the standing crop at the trophic level
Problem is each organism is counted equally.
1000 kg tree = 1 gram grass plant
Units = organisms

11. Pyramid of Biomass
Takes the total biomass of all organisms at each trophic level in the area , and depends on:
the energy available at each trophic level
the standing crop at each trophic level
Problem it is a measure in one instant of time
Unit = grams

13. Population = group of individuals of a single species living in same general area
Density: # individuals / area
Dispersion: pattern of spacing between individuals

14. Determining population size and density:
Count every individual
Random sampling
Mark-recapture method

15. Patterns of Dispersal:
Clumped – most common; near required resource
Uniform – usually antagonistic interactions
Random – not as common as you would think

16. Survivorship Curves:
Type I curve: low death rate early in life (humans)
Type II curve: constant death rate over lifespan (squirrels)
Type III curve: high death rate early in life (oysters)