Ecology and conservation
Ecology and conservation tests populations, communities, sampling, succession, energy flow and conservation. Expect questions on estimating population size, interpreting diversity, explaining human impacts and evaluating conservation methods.
Sampling and populations
- Random sampling avoids bias; quadrats estimate abundance and transects show zonation.
- Mark-release-recapture estimates population size: N = (number marked first x number caught second) / number marked in second sample.
- Species richness is the number of species; diversity also considers abundance and evenness.
Energy flow and conservation
Energy is lost at each trophic level through respiration, heat, excretion and uneaten parts, so pyramids of energy are narrow. Conservation maintains habitats, corridors and sustainable resource use; ex situ methods include seed banks and captive breeding. Succession is the gradual change in community composition over time.
Worked example
40 animals are marked and released. Later, 50 are caught and 8 are marked. N = (40 x 50) / 8 = 250. The estimate assumes marked animals mix randomly, are equally catchable, and the population is closed.
Traps
A high species richness does not always mean high diversity. Percentage cover is not the same as frequency. Energy pyramids are not always inverted; biomass pyramids can be. Do not confuse conservation with preservation.