Package 'spectre'

Matrix of predicted alpha diversity in each cell.

Description

Matrix of predicted alpha diversity in each cell.

Usage

alpha_list

Format

vector.

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calc_commonness_error

Description

Calculate commonness error

Usage

calc_commonness_error(x, objective_matrix)

Arguments

x	Results object from run_optimization_min_conf.
objective_matrix	Matrix from (modeled) alpha-diversity and Bray-Curtis dissimilarity

Details

Calculate mean absolute commonness error (MAE_c) and relative commonness error in percentage (RCE).

Value

vector

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Total (estimated) species in the system.

Description

Total (estimated) species in the system.

Usage

estimated_gamma

Format

numeric

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generate_commonness_matrix_from_gdm

Description

Creates a pairwise site by site commonness matrix from estimates of species richness and Bray-Curtis dissimilarity.

Usage

generate_commonness_matrix_from_gdm(gdm_predictions, alpha_list)

Arguments

gdm_predictions	a square pairwise matrix of Bray-Curtis dissimilarity estimates between site pairs. We recommend using the gdm-package (Fitzpatrick et al. 2020) to generate this matrix
alpha_list	a vector of species richness for every site in the study area. The length of this vector must be equivalent to one of the dimensions of the gdm_predictions

Details

generate_commonness_matrix_from_gdm uses a vector of estimated species richness per site and a pairwise matrix of site by site Bray-Curtis dissimilarity (we recommend using the gdm-package (Fitzpatrick et al. 2020) to generate this matrix) to produce a matrix of the estimated species in common between site pairs (referred to as a commonness matrix). The commonness between sites is calculated using

$C_{ij}=(1-\beta_{ij})(S_{i} + S_{j})/2$

Where $\beta_{ij}$ is the dissimilarity between sites, $C_{ij}$ is the species in common between sites, and S is the number of species in each site. For more details see Mokany et al 2011.

Value

A pairwise site by site matrix of the number of species in common between each site pair, with dimensions equal to that of the provided dissimilarity matrix.

References

Mokany, K., Harwood, T.D., Overton, J.M., Barker, G.M., & Ferrier, S. (2011). Combining $\alpha$ and $\beta$ diversity models to fill gaps in our knowledge of biodiversity. Ecology Letters, 14(10), 1043-1051.

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List with example data created using the gdm package

Description

List with example data created using the gdm package

Usage

minimal_example_data

Format

list

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plot_commonness

Description

Plot commonness between observed and optimized data

Usage

plot_commonness(x, target)

Arguments

x	Results object of run_optimization_min_conf()
target	Pairwise matrix of species in common.

Details

Plot a heatmap of commonness between observed data and optimized data. This visual style allows for easier spatial understanding of commonness differences to be ascertained.

Value

ggplot

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plot_error

Description

Plot the absolute error

Usage

plot_error(x)

Arguments

x	Results object from run_optimization_min_conf

Details

Plot error over time

Value

ggplot

References

xxx

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run_optimization_min_conf

Description

Generate an optimized estimate of community composition (species presences and absences) for every site in the study area.

Usage

run_optimization_min_conf(
  alpha_list,
  total_gamma,
  target,
  max_iterations,
  partial_solution = NULL,
  fixed_species = NULL,
  seed = NA,
  verbose = TRUE,
  interruptible = TRUE
)

Arguments

alpha_list	Matrix of predicted alpha diversity (species richness) in each cell.
total_gamma	Total number of species present throughout the entire landscape.
target	Pairwise matrix of species in common between each site by site pair. Only the upper triangle of the matrix is actually needed.
max_iterations	The maximum number of iterations that the optimization algorithm may run through before stopping.
partial_solution	An initial matrix of species presences and absences for each site in the landscape. The total number of presences must match the estimated species richness of each site.
fixed_species	Fixed partial solution with species that are considered as given. Those species are not going to be changed during optimization.
seed	Seed for random number generator. Seed must be a positive integer value. seed = NA means that a random integer is used as seed.
verbose	If TRUE (default), a progress report is printed during the optimization run.
interruptible	Allow a run to be interrupted before completion.

Details

run_optimization_min_conf is the core function of the spectre package. The underlying algorithm of this function is adapted from Mokany et al. (2011). A pairwise commonness matrix (having the same structure as the target matrix) is calculated from the partial_solution matrix and the value difference with the target determined. If a difference is present and depending on the set stopping criteria the algorithm continues. A random site in the presence/absence matrix is selected, and a random presence record at this site replaced with an absence. Every absence in the selected site is then individually flipped to a presence and the value difference with the objective recorded. The presence record which resulted in the lowest value difference (minimum conflict) is retained. This cycle continues, with a random site selected every iteration, until the pairwise commonness and objective matrices match or the algorithm runs beyond the max_iterations.

Value

A species presence/absence matrix of the study landscape.

References

Mokany, K., Harwood, T.D., Overton, J.M., Barker, G.M., & Ferrier, S. (2011). Combining $\alpha$ and $\beta$ diversity models to fill gaps in our knowledge of biodiversity. Ecology Letters, 14(10), 1043-1051.

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spectre

Description

The goal of spectre is to provide an open source tool capable of predicting regional community composition at fine spatial resolutions using only sparse biological and environmental data.

Author(s)

Maintainer: Craig Simpkins [email protected]

Authors:

• Sebastian Hanss

• Maximilian Hesselbarth

• Matthias Spangenberg

• Jan Salecker

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Pairwise matrix of species in common.

Description

Pairwise matrix of species in common.

Usage

target_matrix

Format

matrix

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