Extended Version of the Birth-Death Models to Estimate Speciation and Extinction Rates
This function fits by maximum likelihood a birth-death model to the combined phylogenetic and taxonomic data of a given clade. The phylogenetic data are given by a tree, and the taxonomic data by the number of species for the its tips.
bd.ext(phy, S, conditional = TRUE)
- an object of class
- a numeric vector giving the number of species for each tip.
- whether probabilities should be conditioned on no extinction (mainly to compare results with previous analyses; see details).
A re-parametrization of the birth-death model studied by Kendall (1948) so that the likelihood has to be maximized over d/b and b - d, where b is the birth rate, and d the death rate.
The standard-errors of the estimated parameters are computed using a normal approximation of the maximum likelihood estimates.
If the argument
S has names, then they are matched to the tip
phy. The user must be careful here since the function
requires that both series of names perfectly match, so this operation
may fail if there is a typing or syntax error. If both series of names
do not match, the values
S are taken to be in the same order
than the tip labels of
phy, and a warning message is issued.
Note that the function does not check that the tree is effectively ultrametric, so if it is not, the returned result may not be meaningful.
conditional = TRUE, the probabilities of the taxonomic data
are calculated conditioned on no extinction (Rabosky et al. 2007). In
previous versions of the present function (until ape 2.6-1),
unconditional probabilities were used resulting in underestimated
extinction rate. Though it does not make much sense to use
conditional = FALSE, this option is provided to compare results
from previous analyses: if the species richnesses are relatively low,
both versions will give similar results (see examples).
Paradis, E. (2003) Analysis of diversification: combining phylogenetic and taxonomic data. Proceedings of the Royal Society of London. Series B. Biological Sciences, 270, 2499--2505.
Rabosky, D. L., Donnellan, S. C., Talaba, A. L. and Lovette, I. J. (2007) Exceptional among-lineage variation in diversification rates during the radiation of Australia's most diverse vertebrate clade. Proceedings of the Royal Society of London. Series B. Biological Sciences, 274, 2915-2923.
### An example from Paradis (2003) using the avian orders: data(bird.orders) ### Number of species in each order from Sibley and Monroe (1990): S <- c(10, 47, 69, 214, 161, 17, 355, 51, 56, 10, 39, 152, 6, 143, 358, 103, 319, 23, 291, 313, 196, 1027, 5712) bd.ext(bird.orders, S) bd.ext(bird.orders, S, FALSE) # same than older versions