# untb

##### Ecological drift simulation under the Unified Neutral Theory of Biodiversity

Simulates ecological drift under the UNTB. Function `untb()`

carries out the simulation; function `select()`

carries out a single generational step.

- Keywords
- math

##### Usage

```
untb(start, prob=0, D=1, gens=150, keep=FALSE, meta=NULL)
select(a, D=length(a), prob=0, meta=NULL)
select.mutate(a, D=length(a), prob.of.mutate=0)
select.immigrate(a, D=length(a), prob.of.immigrate=0, meta)
```

##### Arguments

- a, start
Starting ecosystem; coerced to class census. Usually, pass an object of class count; see examples. To start with a monoculture of size 10, use

`start=rep(1,10)`

and to use`start=1:10`

.- prob, prob.of.immigrate, prob.of.mutate
Probability of “new” organism not being a descendent of an existing individual

- D
Number of organisms that die in each timestep

- gens
Number of generations to simulate

- keep
In function

`untb()`

Boolean with default`FALSE`

meaning to return the system at the end of the simulation and`TRUE`

meaning to return a matrix whose rows are the ecosystem at successive times- meta
In function

`untb()`

, the metacommunity; coerced to a`count`

object. Default of`NULL`

means to use a “greedy” system in which every mutation gives rise to a new, previously unencountered species. This would correspond to an infinitely large, infinitely diverse, Hubbellian ecosystem (which is not too ridiculous an assumption for a small island near a large diverse mainland).In function

`select.immigrate()`

, a simplified representation of a metacommunity.

##### Details

Functions `select.immigrate()`

and `select.mutate()`

are not
really intended for the end user; they use computationally efficient
(and opaque) integer arithmetic.

##### References

S. P. Hubbell 2001. “The Unified Neutral Theory of Biodiversity”. Princeton University Press.

##### Examples

```
# NOT RUN {
data(butterflies)
untb(start=butterflies, prob=0, gens=100)
a <- untb(start=1:10,prob=0.005, gens=1000,keep=TRUE)
plot(species.count(a),type="b")
matplot(species.table(a),type="l",lty=1)
# }
```

*Documentation reproduced from package untb, version 1.7-4, License: GPL*