Estimate Evenness measures

This function calculates community evenness indices. These include the ‘Camargo’, ‘Pielou’, ‘Simpson’, ‘Evar’ and ‘Bulla’ evenness measures. See details for more information and references.

estimateEvenness(
  x,
  assay.type = assay_name,
  assay_name = "counts",
  index = c("pielou", "camargo", "simpson_evenness", "evar", "bulla"),
  name = index,
  ...
)

# S4 method for SummarizedExperiment
estimateEvenness(
  x,
  assay.type = assay_name,
  assay_name = "counts",
  index = c("camargo", "pielou", "simpson_evenness", "evar", "bulla"),
  name = index,
  ...,
  BPPARAM = SerialParam()
)

Arguments

x

a SummarizedExperiment object

assay.type

A single character value for selecting the assay used for calculation of the sample-wise estimates.

assay_name

a single character value for specifying which assay to use for calculation. (Please use assay.type instead. At some point assay_name will be disabled.)

index

a character vector, specifying the evenness measures to be calculated.

name

a name for the column(s) of the colData the results should be stored in.

...

optional arguments:

• threshold a numeric threshold. assay values below or equal to this threshold will be set to zero.

BPPARAM

A BiocParallelParam object specifying whether calculation of estimates should be parallelized.

Value

x with additional colData named *name*

Details

Evenness is a standard index in community ecology, and it quantifies how evenly the abundances of different species are distributed. The following evenness indices are provided:

By default, this function returns all indices.

The available evenness indices include the following (all in lowercase):

• 'camargo' Camargo's evenness (Camargo 1992)

• 'simpson_evenness' Simpson’s evenness is calculated as inverse Simpson diversity (1/lambda) divided by observed species richness S: (1/lambda)/S.

• 'pielou' Pielou's evenness (Pielou, 1966), also known as Shannon or Shannon-Weaver/Wiener/Weiner evenness; H/ln(S). The Shannon-Weaver is the preferred term; see Spellerberg and Fedor (2003).

• 'evar' Smith and Wilson’s Evar index (Smith & Wilson 1996).

• 'bulla' Bulla’s index (O) (Bulla 1994).

Desirable statistical evenness metrics avoid strong bias towards very large or very small abundances; are independent of richness; and range within the unit interval with increasing evenness (Smith & Wilson 1996). Evenness metrics that fulfill these criteria include at least camargo, simpson, smith-wilson, and bulla. Also see Magurran & McGill (2011) and Beisel et al. (2003) for further details.

References

Beisel J-N. et al. (2003) A Comparative Analysis of Evenness Index Sensitivity. Internal Rev. Hydrobiol. 88(1):3-15. URL: https://portais.ufg.br/up/202/o/2003-comparative_evennes_index.pdf

Bulla L. (1994) An index of evenness and its associated diversity measure. Oikos 70:167--171.

Camargo, JA. (1992) New diversity index for assessing structural alterations in aquatic communities. Bull. Environ. Contam. Toxicol. 48:428--434.

Locey KJ and Lennon JT. (2016) Scaling laws predict global microbial diversity. PNAS 113(21):5970-5975; doi:10.1073/pnas.1521291113.

Magurran AE, McGill BJ, eds (2011) Biological Diversity: Frontiers in Measurement and Assessment (Oxford Univ Press, Oxford), Vol 12.

Pielou, EC. (1966) The measurement of diversity in different types of biological collections. J Theoretical Biology 13:131--144.

Smith B and Wilson JB. (1996) A Consumer's Guide to Evenness Indices. Oikos 76(1):70-82.

Spellerberg and Fedor (2003). A tribute to Claude Shannon (1916 –2001) and a plea for more rigorous use of species richness, species diversity and the ‘Shannon–Wiener’ Index. Alpha Ecology & Biogeography 12, 177–197.

See also

plotColData

• estimateRichness

• estimateDominance

• estimateDiversity

Examples

data(esophagus)
tse <- esophagus

# Specify index and their output names
index <- c("pielou", "camargo", "simpson_evenness", "evar", "bulla")
name  <- c("Pielou", "Camargo", "SimpsonEvenness",  "Evar", "Bulla")

# Estimate evenness and give polished names to be used in the output
tse <- estimateEvenness(tse, index = index, name = name)

# Check the output
head(colData(tse))
#> DataFrame with 3 rows and 5 columns
#>      Pielou   Camargo SimpsonEvenness      Evar     Bulla
#>   <numeric> <numeric>       <numeric> <numeric> <numeric>
#> B  0.675039  0.694229       0.2117931  0.372309  0.362708
#> C  0.790042  0.623054       0.3135170  0.407399  0.489706
#> D  0.558748  0.801009       0.0787307  0.482015  0.351968