It is not just people crossing the ditch – a little New Zealand
fern has also emigrated to Australia, and not just once but
twice. This is the first known case amongst ferns or seed plants
of the same species dispersing twice across the Tasman Sea.
Hooker’s spleenwort fern, or Asplenium hookerianum, is a close
relative of the hen & chickens ferns. Hooker’s spleenwort is
widespread and common in New Zealand, but rare in Australia,
with only a few, small populations in each of Victoria and
Tasmania. DNA analyses of the populations of Hooker’s spleenwort
were carried out by researchers from Te Papa, Massey University,
and the University of Melbourne. 26 genetic variants were found
in New Zealand, but only one each in Victoria and Tasmania. Not
only are the Australian variants at the tips of the genetic
family tree, they are more closely related to variants in New
Zealand than to each other. Many plant species are known to have
dispersed across the Tasman Sea, in either direction. Numerous
New Zealand species als