Dr Leon Perrie from Te Papa explains long-distance dispersal and tells us what influence it has had on New Zealand fern origins. His research has revealed a few surprises.
Point of interest involving the nature of science: Long-distance dispersal is an example of how advances in technology allow scientists to revise and discard theories.
DR LEON PERRIE
Long-distance dispersal is usually thought of as the dispersal or the movement of a plant or animal across a long distance of unsuitable habitat. So for ferns, for instance, if we were to imagine a fern spore blowing from New Zealand to Australia and that fern spore then successfully colonised in Australia, that would be long-distance dispersal because, of course, the Tasman Sea is an area of unsuitable habitat for a fern.
I am interested in long-distance dispersal because I want to know what influence it has had on the origins of New Zealand’s ferns. Have they been here a long time? Have they been long isolated on New Zealand? – because New Zealand has been isolated or surrounded by water for a long, long time – several tens of millions of years – or have New Zealand’s ferns arrived here by long-distance dispersal?
And what we have learnt from our analyses, particularly using DNA sequences to compare how New Zealand ferns are related to those overseas, is that our ferns have not been long isolated in New Zealand. There’s been a lot of arrivals, recent arrivals by long-distance dispersal, but there’s also been immigration as well where New Zealand ferns have colonised other parts of the world successfully. So there’s been comings and goings in the New Zealand fern flora.
1887 Mature trees ferns in a clearing in bush A-045-001
Edward William Payton: Tree ferns, Wellington.
Ca 1990 Tree ferns at Pukekura Park, New Plymouth.
William Andrews Collis. 1/2-021395-G
Alexander Turnbull library
Permission of the Alexander Turnbull library, Wellington, New Zealand, must be obtained before any re-use of these images.