ES.May {asbio}

May's effective specialization index

Description

May and Beverton (1990) created the effective specialization index to quantify the degree of specialization of insects with potential host plants.

Usage

ES.May(mat, digs = 3)

Arguments

mat

A symmetric matrix with potential specialist hosts in rows and and the number species specializing on each of the host species in columns (see details below).

digs

The number of significant digits in output.

Details

The structure of the object mat is nonintuitive. In the rows of the matrix are species which can be selected by potential specialists (i.e. hosts). May and Beverton (1990) used four oak species. The columns indicate the degree of specialization of potential specialists. May and Beverton (1990) were interested in the specialization of beetles. The first element (row 1, column 1) in their 4 x 4 matrix contained only beetle species found on host 1. The second element (row 1, column 2) contained the number of beetle species found on host 1 and one other host. The third element (row 1, column 3) contained the number of beetle species found on host 1 and two other hosts. The fourth element (row 1, column 4) contained the number of beetle species occurring on all four hosts.

Value

Output is a list

E.S_coefficients

Nk

The number of distinct specialists.

Pki.matrix

The proportion of potential specialists on the kth host

N.matrix

The raw data.

fk.matrix

fk.vector

For the kth host, the proportion of species which are effectively specialized.

Nk.vector

The number of species which are effectively specialized on the kth host.

Author(s)

Ken Aho and Jessica Fultz

References

May, R. M. and Beverton, R. J. H. (1990) How many species [and discussion]. Philosophical Transactions: Biological Sciences. 330 (1257) 293-304.

Examples

#data from May and Beverton (1990)
beetle<-matrix(ncol=4,nrow=4,data=c(5,8,7,8,20,10,9,8,14,15,11,8,15,15,12,8), 
byrow=TRUE)
ES.May(beetle)