sim_env_bd {RPANDA}

Simulate birth-death tree dependent on an environmental curve

Description

Simulates a birth-death tree (starting with one lineage) with speciation and/or extinction rate that varies as a function of an input environmental curve. Notations follow Morlon et al. PNAS 2011 and Condamine et al. ELE 2013.

Usage

sim_env_bd(env_data, f.lamb, f.mu, lamb_par, mu_par, df=NULL, time.stop=0, 
			return.all.extinct=TRUE, prune.extinct=TRUE)

Arguments

env_data

environmental data, given as a data frame with two columns. The first column is time, the second column is the environmental data (temperature for instance).

time.stop

the age of the phylogeny.

f.lamb

a function specifying the hypothesized functional form of the variation of the speciation rate \lambda with time and the environmental variable. Any functional form may be used. This function has three arguments: the first argument is time; the second argument is the environmental variable; the third arguement is a numeric vector of the parameters controlling the time and environmental variation (to be estimated).

f.mu

a function specifying the hypothesized functional form of the variation of the extinction rate \mu with time and the environmental variable. Any functional form may be used. This function has three arguments: the first argument is time; the second argument is the environmental variable; the second argument is a numeric vector of the parameters controlling the time and environmental variation (to be estimated).

lamb_par

a numeric vector of initial values for the parameters of f.lamb to be estimated (these values are used by the optimization algorithm). The length of this vector is used to compute the total number of parameters in the model, so to fit a model with constant speciation rate (for example), lamb_par should be a vector of length 1. Otherwise aic values will be wrong.

mu_par

a numeric vector of initial values for the parameters of f.mu to be estimated (these values are used by the optimization algorithm). The length of this vector is used to compute the total number of parameters in the model, so to fit a model without extinction (for example), mu_par should be empty (vector of length 0). Otherwise aic values will be wrong.

df

the degree of freedom to use to define the spline. As a default, smooth.spline(env_data[,1], env_data[,2])$df is used. See sm.spline for details.

return.all.extinct

return all extinction lineages in simulated tree.

prune.extinct

prune extinct lineages in simulated tree.

Details

In the f.lamb and f.mu functions, time runs from the present to the past.

Value

a list with the following components

tree

the simulated tree with number tips

times

the times of speciation events starting from the past

nblineages

the labels of surviving lineages and total number of surviving lineages

Note

The speed of convergence of the fit might depend on the degree of freedom chosen to define the spline.

Author(s)

E Lewitus and H Morlon

References

Morlon, H., Parsons, T.L. and Plotkin, J.B. (2011) Reconciling molecular phylogenies with the fossil record Proc Nat Acad Sci 108: 16327-16332

Condamine, F.L., Rolland, J., and Morlon, H. (2013) Macroevolutionary perspectives to environmental change, Eco Lett 16: 72-85

See Also

fit_env, fit_bd

Examples

data(InfTemp)
dof<-smooth.spline(InfTemp[,1], InfTemp[,2])$df
# Simulates a tree with lambda varying as an exponential function of temperature
# and mu fixed to 0 (no extinction).  Here t stands for time and x for temperature.
f.lamb <-function(t,x,y){y[1] * exp(y[2] * x)}
f.mu<-function(t,x,y){0}
lamb_par<-c(0.10, 0.01)
mu_par<-c()
#result_exp <- sim_env_bd(InfTemp,f.lamb,f.mu,lamb_par,mu_par,time.stop=10)