Intra- and interspecific trait variability

Decomposes variation in community trait means into the part caused by species turnover (interspecific) and the part caused by trait change within species (intraspecific), following Leps et al. (2011). It compares the specific average (CWM from site-specific species means) with the fixed average (CWM from species means over all sites).

Usage

trait_itv(
  data,
  traits,
  site = site,
  species = species,
  abundance = NULL,
  cols,
  formula = NULL
)

Arguments

data

A data frame in long format, with one row per record.

traits

A data frame of trait values measured per site: columns for site, species and the trait(s). Several rows per site and species (individuals) are averaged.

site, species

<tidy-select> The column holding site identifiers and the column holding species names.

abundance

<tidy-select> The column holding counts. If NULL (the default), a column called abundance is used when present, otherwise every row counts as one individual.

cols

<tidy-select> Trait columns of traits.

formula

Optional one-sided formula of site variables. If given, the sums of squares are those explained by the formula; otherwise the total sums of squares are decomposed.

Value

A tibble with one row per trait and component ("turnover", "intraspecific", "covariation", "total"), the sum of squares ss and its share prop of the total.

References

Leps, J. et al. (2011). Community trait response to environment: disentangling species turnover vs intraspecific trait variability effects. Ecography, 34, 856-863. doi:10.1111/j.1600-0587.2010.06904.x