\item{model}{a character string specifying the evlutionary model to be
used; must be one of \code{"raw"}, \code{"N"}, \code{"JC69"},
\code{"K80"} (the default), \code{"F81"}, \code{"K81"},
\item{model}{a character string specifying the evlutionary model to be
used; must be one of \code{"raw"}, \code{"N"}, \code{"JC69"},
\code{"K80"} (the default), \code{"F81"}, \code{"K81"},