The consensus phylogram from the Bayesian phylogenetic inference of 33 NIP isoforms from various plant species. Rat AQP9 (rAQP9) was used as an out-group. Support values are given below the branches as Bayesian posterior probabilities or jackknife values from the parsimony analysis (cut-off threshold corresponding to 50% for both); the latter is specified as applicable. The scale given below the phylogram refers to expected changes per site. The NIP proteins tested in this paper are in bold and those that transport As(III) are marked with an asterisk (*). The NIPI and NIPII subgroups are indicated with a vertical bar and an arrow indicates the hypothetical point in evolution where the NIPI subgroup may have lost the capacity to transport metalloids.