untb (version 1.7-2)

isolate: Randomly select a subset of an ecosystem

Description

Return an ecosystem comprised of individuals randomly sampled from a metacommunity

Usage

isolate(a, size = no.of.ind(a), replace = TRUE)

Arguments

a

Ecosystem data

size

Number of individuals to sample

replace

Boolean, with default TRUE meaning to sample individuals from the metacommunity with replacement and FALSE meaning to sample without replacement. See details section

Value

Returns a count object

Details

Setting argument replace to default TRUE is much faster.

The canonical example is given by Leigh et al 1993, in which islands were isolated from the mainland by rising waters. The trees on the islands were held to be a randomly drawn sample from the metacommunity.

Given that the usual usage of this function is to generate a plausible ecosystem under such a scenario, one would have a hard time justifying the use of replace=TRUE as it allows (for example) a singleton metacommunity species to have multiple representatives in the returned ecosystem.

However, for large metacommunities and small subsamples, the distinction between replace=TRUE and replace=FALSE is small.

References

E. G. Leigh and others 1993. “The decline of tree diversity on newly isolated tropical islands: a test of a null hypothesis and some implications”. Evolutionary Ecology, 7:76-102

Examples

a <- rand.neutral(1000,10)
no.of.spp(a)
no.of.spp(isolate(a))