r-strategy: species that typically have a relatively short life span; reproduce once and have a large quantity of offspring; observed in unstable environments
traits associated with r-strategy:
small body size
short life spans and generations
fast reproduction
ability to widely disperse offspring
K-Strategy
k-strategy: organisms that can reproduce several times during their lifespan, but the offspring are much slower in reaching maturity; observed in stable environments
traits associated with K-strategy
larger body size
longer life span and generations
Population Sampling
population sampling methods
random sampling
quadrats
transect
capture-mark-release
Random Sampling:
random sampling: finding the distribution of species or comparing distributions in different locations
Finding the distribution of species or comparing distributions in different locations
Gives a good representation of the population
Assumes every organism has an equal chance of being sampled
Capture- Mark - Release:
<<capture mark release steps<<
<<A large sample of the specimen must be trapped/netted (without causing harm)<<
<<The number of captured organisms is counted and recorded<<
<<Captured animals are marked (eg. Non-toxic dye, clipping fur)<<
<<Animals are returned to the wild and allowed to reintegrate.<<
<<A second sample of the specimen is collected from the population after some time.<<
<<The numbers of marked and unmarked animals in the new sample are counted and recorded.<<
The population size is calculated using the Lincoln Index formula:
Quadrats:
quadrant: square made up of wood or metal, placed on the ground; the organisms found in the quadrats are counted
<<process of quadrats:<<
<<Divide the area that needs to be surveyed into 1m squares and give it quadrants<<
<<Use a random # generator to determine which grid squares to use<<
<<Count the number of organisms in the selected squares<<
<<Average the number found in 1m^2 and multiply by the total number of squares in that survey area!<<
Transects:
transect: shows the distribution of species in relation to abiotic factors or changes in communities of organisms across a habitat
Systematic rather than random
Stretch tape/rope from a fixed point across the changing habitat
At intervals (10m, or what is suitable) along the tape, put down a quadrat and count the organisms inside it.
Gives a series of samples
Measure the abiotic factor of interest at each quadrat location (ie: temperature, salinity, soil pH)
<<Process:<<
<<Stretch tape/rope from a fixed point across the changing habitat<<
<<At intervals (10m, or what is suitable) along the tape, put down a quadrat and count the organisms inside it.<<
<<Gives a series of samples<<
<<Measure the abiotic factor of interest at each quadrat location (ie: temperature, salinity, soil pH)<<
Biotic Index
Found by surveying and sampling organisms present
Each species is given a 'sensitive factor' which indicates its ability to tolerate pollution
high biotic index = sensitive species = good quality
low biotic index = tolerant species = low quality
species richness: the number of different species present
