19.5 Investigating populations Flashcards
what does investigating populations look into/
distribution
abundance
define distribution
where a particular species is within an area
define abundance
number of individuals of one species in a particular area (population size)
what is abundance estimated by
- count no. of individuals in samples
- frequency
- calculate % cover
what are the two methods of investigating populations?
- random sampling using quadrats
- mark, release, recapture
what is random sampling using quadrats used for
slow-moving
non motile
what is mark, release, recapture used for
mobile organisms
why is random sampling reliable
- rng = avoids bias
- repeats = decreases chance
- calculate mean value
main points for mark, release, recapture
- capture and mark individuals
- release and give enough time for reintegration
- capture and count marked
- calculate estimated population size
how should you mark the individuals and what with
in a way that won’t kill them or get them killed
what is the equation for calculating estimated population size
(initial sample x last sample) / no. of marked on last sample
2 methods of random sampling
- random quadrats
- line transects
main points for random sampling using quadrats
- use 2 tape measures at right angles (gridded area)
- use a random num gen for coords
- place quadrat and collect data (count)
- repeat several times and calculate mean
what 2 types of line transects are there
- belt transect
- interrupted belt transect
main points of line transects
- lay out tape measure
- place quadrat at every position/ same intervals
- collect data (count)
- repeat by doing other transects along
