C4.1 :

• Population :

  Group of individuals of the same species living in the same period of time, same geographical area and are able to interbreed.
• Isolation :

  Reproductive isolation : If individuals are able to interbreed.

  Geographical isolation : If individuals are in the same geographical area (possible physical seperation).

  Behavioural isolation : If individuals are able to engage in specific behaviour involved in mating.

  Temporal isolation : If individuals exist in the same time period.
• Reason for estimating population size :

  Due to the fact that population size is relatively large -> hard to measure all of them.

  Assess ecological health, species dynamic & conservation efforts.
• Sampling error :

  Difference between the actual number in a population & the estimated number in a population.
• Random sampling :

  Randomly choosen quadrats in a geographical area are choosen and are sampled.

  Prevents any biases from arising.
• Systematic sampling :

  Where a line (transect) is used and samples are collected every regular interval.
• Need for randomness in sampling :

  Minimise biases & collect a representative sample of the whole population.