hill {benthos}

Hill's Diversity Numbers

Description

According to Hill (1973): "a diversity number is figuratively a measure of how many species are present if we examine the sample down to a certain depth among its rarities. If we examine superficially (e.g., by using N_2) we shall see only the more abundant species. If we look deeply (e.g., by using N_0) we shall see all the species present."

Hill's diversity numbers are given by:

N_a=\sum{i=1}^S (p_i^a)^{1/(1-a)}

Special cases are:

N_{-\infty}

reciprocal of the proportional abundance of the rarest species;

N_0

total number of species present;

N_1

exp(H), where H: Shannon's index (see also shannon);

N_2

reciprocal of Simpson's index (see also simpson);

N_{\infty}

reciprocal of the proportional abundance of the commonest species.

Usage

hill(.data = NULL, taxon, count, a = 0)

hill_(.data = NULL, taxon, count, a = 0)

hill0(.data = NULL, taxon, count)

hill0_(.data = NULL, taxon, count)

hill1(.data = NULL, taxon, count)

hill1_(.data = NULL, taxon, count)

hill2(.data = NULL, taxon, count)

hill2_(.data = NULL, taxon, count)

Arguments

.data

data in a data.frame, tibble, data.table, database etc.

taxon

name of column in .data containing taxa

count

name of column in .data containing counts

a

exponent in Hill's diversity number (R, with special cases for a in 0, 1, 2 (see details))

Value

numeric vector of Hill's numbers

Functions

• hill_(): version suitable for calling from a function (see package lazyeval).

• hill0(): N_0

• hill0_(): N_0, version suitable for calling from a function (see package lazyeval).

• hill1(): N_1

• hill1_(): N_1, version suitable for calling from a function (see package lazyeval).

• hill2(): N_2

• hill2_(): N_2, version suitable for calling from a function (see package lazyeval).

References

Hill, M.O., 1973. Diversity and Evenness: A Unifying Notation and Its Consequences. Ecology 54:427-432

See Also

species_richness, shannon, simpson

Examples

     hill(
         taxon = c("Euspira pulchella", "Nephtys cirrosa"),  
         count = c(6, 12),
         a = 0
     )
     hill0(
         taxon = c("Euspira pulchella", "Nephtys cirrosa"),  
         count = c(6, 12)
     )