isolate
Randomly select a subset of an ecosystem
Return an ecosystem comprised of individuals randomly sampled from a metacommunity
- Keywords
- math
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 andFALSE
meaning to sample without replacement. See details section
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.
Value
-
Returns a
count
object
Note
If replace=FALSE
, the returned count object includes extinct
species. Use extant(isolate(...))
to return only extant species
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))