intra_influ_phylm {sensiPhy}

Interaction between intraspecific variability and influential species - Phylogenetic Linear Regression

Description

Performs leave-one-out deletion analysis for phylogenetic linear regression, and detects influential species, while taking into account potential interactions with intraspecific variability.

Usage

intra_influ_phylm(
  formula,
  data,
  phy,
  Vy = NULL,
  Vx = NULL,
  y.transf = NULL,
  x.transf = NULL,
  n.intra = 10,
  distrib = "normal",
  model = "lambda",
  cutoff = 2,
  track = TRUE,
  ...
)

Arguments

formula

The model formula: response~predictor.

data

Data frame containing species traits with row names matching tips in phy.

phy

A phylogeny (class 'phylo') matching data.

Vy

Name of the column containing the standard deviation or the standard error of the response variable. When information is not available for one taxon, the value can be 0 or NA.

Vx

Name of the column containing the standard deviation or the standard error of the predictor variable. When information is not available for one taxon, the value can be 0 or NA

y.transf

Transformation for the response variable (e.g. "log" or "sqrt"). Please use this argument instead of transforming data in the formula directly (see also details below).

x.transf

Transformation for the predictor variable (e.g. "log" or "sqrt"). Please use this argument instead of transforming data in the formula directly (see also details below).

n.intra

Number of datasets resimulated taking into account intraspecific variation (see: "intra_phylm")

distrib

A character string indicating which distribution to use to generate a random value for the response and/or predictor variables. Default is normal distribution: "normal" (function rnorm). Uniform distribution: "uniform" (runif) Warning: we recommend to use normal distribution with Vx or Vy = standard deviation of the mean.

model

The phylogenetic model to use (see Details). Default is lambda.

cutoff

The cutoff value used to identify for influential species (see Details)

track

Print a report tracking function progress (default = TRUE)

...

Further arguments to be passed to phylolm

Details

This function fits a phylogenetic linear regression model using phylolm, and detects influential species by sequentially deleting one at a time. The regression is repeated n.intra times for simulated values of the dataset, taking into account intraspecific variation. At each iteration, the function generates a random value for each row in the dataset using the standard deviation or errors supplied, and detect the influential species within that iteration.

All phylogenetic models from phylolm can be used, i.e. BM, OUfixedRoot, OUrandomRoot, lambda, kappa, delta, EB and trend. See ?phylolm for details.

influ_phylm detects influential species based on the standardised difference in intercept and/or slope when removing a given species compared to the full model including all species. Species with a standardised difference above the value of cutoff are identified as influential. The default value for the cutoff is 2 standardised differences change.

Currently, this function can only implement simple linear models (i.e. trait~ predictor). In the future we will implement more complex models.

Output can be visualised using sensi_plot.

Value

The function intra_influ_phylm returns a list with the following components:

cutoff: The value selected for cutoff

formula: The formula

full.model.estimates: Coefficients, aic and the optimised value of the phylogenetic parameter (e.g. lambda) for the full model without deleted species.

influential_species: List of influential species, both based on standardised difference in intercept and in the slope of the regression. Species are ordered from most influential to less influential and only include species with a standardised difference > cutoff.

sensi.estimates: A data frame with all simulation estimates. Each row represents a deleted clade for an iteration of resimulated data. Columns report the calculated regression intercept (intercept), difference between simulation intercept and full model intercept (DIFintercept), the standardised difference (sDIFintercept), the percentage of change in intercept compared to the full model (intercept.perc) and intercept p-value (pval.intercept). All these parameters are also reported for the regression slope (DIFestimate etc.). Additionally, model aic value (AIC) and the optimised value (optpar) of the phylogenetic parameter (e.g. kappa or lambda, depending on the phylogenetic model used) are reported.

data: Original full dataset.

errors: Species where deletion resulted in errors.

Warning

When Vy or Vx exceed Y or X, respectively, negative (or null) values can be generated, this might cause problems for data transformation (e.g. log-transformation). In these cases, the function will skip the simulation.

Setting n.intra at high values can take a long time to execute, since the total number of iterations equals n.intra * nrow(data).

Author(s)

Gustavo Paterno, Caterina Penone & Gijsbert D.A. Werner

References

Paterno, G. B., Penone, C. Werner, G. D. A. sensiPhy: An r-package for sensitivity analysis in phylogenetic comparative methods. Methods in Ecology and Evolution 2018, 9(6):1461-1467.

Ho, L. S. T. and Ane, C. 2014. "A linear-time algorithm for Gaussian and non-Gaussian trait evolution models". Systematic Biology 63(3):397-408.

See Also

phylolm, intra_phylm, influ_phylm,intra_influ_phyglm,sensi_plot.

Examples

## Not run: 
# Load data:
data(alien)
# run analysis:
intra_influ <- intra_influ_phylm(formula = gestaLen ~ adultMass, phy = alien$phy[[1]],
data=alien$data,model="lambda",y.transf = log,x.transf = NULL,Vy="SD_gesta",Vx=NULL,
n.intra=30,distrib = "normal")
summary(intra_influ)
sensi_plot(intra_influ)

## End(Not run)