# Zeta distance decay for a range of numbers of assemblages or sites

### Description

Computes the distance decay of zeta diversity for a range of orders (number of assemblages or sites), using linear regressions.

### Usage

1 2 | ```
Zeta.ddecays(xy, data.spec, orders = 2:10, sam = 1000,
confint.level = 0.95, method = "mean", plot = TRUE)
``` |

### Arguments

`xy` |
Site-by-coordinate data frame, with sites as rows and coordinates as columns. |

`data.spec` |
Site-by-species presence-absence data frame, with sites as rows and species as columns. |

`orders` |
Range of number of assemblages or sites at which zeta diversity is computed. All the orders must be striclty greater than 1. |

`sam` |
Number of samples for which the zeta-diversity is computed. |

`confint.level` |
Percentage for the confidence intervals of the coefficient from the linear regression. |

`method` |
Indicates which distance to consider for more than 3 sites. Method can be " |

`plot` |
Boolean value (TRUE or FALSE) indicating if the outputs must be plotted. |

### Value

`Zeta.ddecays`

returns a list containing the following components:

`coefs` |
A vector of the coefficients from the linear regressions over distance for the numbers of sites specified by 'order'. |

`confint` |
The confidence intervals for the coefficients from the linear regressions. |

### References

Hui C. & McGeoch M.A. (2014). Zeta diversity as a concept and metric that unifies incidence-based biodiversity patterns. *The American Naturalist*, 184, 684-694.

### See Also

`Zeta.decline`

, `Zeta.order`

, `Zeta.ddecay`

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | ```
data(BCI.spec.coarse)
xy <- BCI.spec.coarse[1:2]
data.spec <- BCI.spec.coarse[3:308]
dev.new()
zeta.ddecays <- Zeta.ddecays(xy, data.spec, sam = 100, orders = 2:5,
plot = TRUE, confint.level = 0.95)
##########
data(Marion.species)
xy <- Marion.species[1:2]
data.species <- Marion.species[3:33]
dev.new()
zeta.ddecays.species <- Zeta.ddecays(xy, data.species, sam = 100, orders = 2:5,
plot = TRUE, confint.level = 0.95)
``` |