These are all `methods' of generic functions which are here applied to
  DNA sequences stored as objects of class "DNAbin". They are
  used in the same way than the standard R functions to manipulate
  vectors, matrices, and lists. Additionally, the operators [[
  and $ may be used to extract a vector from a list. Note that
  the default of drop is not the same than the generic operator:
  this is to avoid dropping rownames when selecting a single sequence.
These functions are provided to manipulate easily DNA sequences coded
  with the bit-level coding scheme. The latter allows much faster
  comparisons of sequences, as well as storing them in less memory
  compared to the format used before ape 1.10.
For cbind, the default behaviour is to keep only individuals
  (as indicated by the rownames) for which there are no missing data. If
  fill.with.gaps = TRUE, a `complete' matrix is returned,
  enventually with insertion gaps as missing data. If check.names
  = TRUE (the default), the rownames of each matrix are checked, and
  the rows are reordered if necessary (if some rownames are duplicated,
  an error is returned). If check.names = FALSE, the matrices
  must all have the same number of rows, and are simply binded; the
  rownames of the first matrix are used. See the examples.
as.matrix may be used to convert DNA sequences (of the same
  length) stored in a list into a matrix while keeping the names and the
  class. as.list does the reverse operation.