Niche width and individual specialisation indices

Calculate indices of niche width and individual specialisation, following Bolnick et al. 2002 (doi:10.1890/0012-9658(2002)083[2936:MILRS]2.0.CO;2 ).

TNW calculates the Total Niche Width of the population, using Shannon diversity.

WIC calculates the Within-Individual Component of niche width as a weighted average of individuals' Shannon diversity (i.e. the Shannon diversity value of each individual plant is weighted by the proportion of visits or interactions received by that plant). WIC can also return the individual Shannon diversity values, if indiv = TRUE.

indiv_spec returns a data.frame with the following columns:

• WIC (Within-Individual Component)

• TNW (Total Niche Width)

• IndSpec (Individual Specialisation index, calculated as the ratio WIC / TNW).

Usage

indiv_spec(net)

TNW(net)

WIC(net, indiv = FALSE)

Arguments

net

A matrix or data.frame containing interaction data. Plants in rows, Animals in columns. Numbers need not be integers (i.e. counts), can be relative abundances or interaction frequencies.

indiv

Logical. If TRUE, return individual Shannon diversity values. If FALSE, return the weighted average of individual Shannon diversity, weighted by the proportion of interactions represented by each plant (i.e. the WIC).

Value

A numeric value or vector for WIC and TNW, a data.frame in the case of indiv_spec

Note

Ideally net should not contain missing data (NA). If present, they will be ignored.

References

Bolnick DI, LH Yang, JA Fordyce, JM Davis, and Svanback R. 2002. Measuring individual-level resource specialization. Ecology 83: 2936-2941.

See also

RInSp::WTdMC()

Examples

data(web)
net <- long2wide(web)

indiv_spec(net)
#>       WIC      TNW   IndSpec
#> 1 1.71828 2.008202 0.8556311
WIC(net)
#>     WIC 
#> 1.71828 
WIC(net, indiv = TRUE)
#> [1] 1.890557 1.504788 1.889159 1.329661
TNW(net)
#>      TNW 
#> 2.008202