A rank abundance curve or Whittaker plot is a chart used by ecologists to display
relative species abundance, a component of
biodiversity. It can also be used to visualize
species richness and
species evenness. It overcomes the shortcomings of
biodiversity indices that cannot display the relative role different variables played in their calculation.
The curve is a 2D chart with relative abundance on the Y-axis and the abundance rank on the X-axis.
* X-axis: The abundance rank. The most abundant species is given rank 1, the second most abundant is 2 and so on.
* Y-axis: The relative abundance. Usually measured on a log scale, this is a measure of a
species abundance
In ecology, local abundance is the relative representation of a species in a particular ecosystem. It is usually measured as the number of individuals found per sample. The ratio of abundance of one species to one or multiple other species livin ...
(e.g., the number of individuals) relative to the abundance of other species.
Interpreting a rank abundance curve
The rank abundance curve visually depicts both species richness and species evenness. Species richness can be viewed as the number of different species on the chart i.e., how many species were ranked. Species evenness is reflected in the slope of the line that fits the graph (assuming a linear, i.e. logarithmic series, relationship). A steep gradient indicates low evenness as the high-ranking species have much higher abundances than the low-ranking species. A shallow gradient indicates high evenness as the abundances of different species are similar.
Quantitative comparison of rank abundance curves
Quantitative comparison of rank abundance curves of different communities can be done using RADanalysis package in
R. This package uses the
max rank normalization
Max or MAX may refer to:
Animals
* Max (dog) (1983–2013), at one time purported to be the world's oldest living dog
* Max (English Springer Spaniel), the first pet dog to win the PDSA Order of Merit (animal equivalent of OBE)
* Max (gorilla) ( ...
method
in which a rank abundance distribution is made by normalization of rank abundance curves of communities to the same number of ranks and then normalize the relative abundances to one.
References
*
*
;Specific
External links
*
Whittaker Diagram', Procedural Content Generation Wiki - use of Whittaker diagrams in procedural content generation
*
RADanalysis package in R', Package in CRAN contain functions for quantitative comparison of rank abundance curves
{{DEFAULTSORT:Rank Abundance Curve
Biodiversity
Systems ecology
Statistical charts and diagrams