High Genetic Diversity in an Ancient Hawaiian Clone
ScienceDaily (Dec. 22, 2011) — The entire Hawaiian population of the peat moss Sphagnum palustre appears to be a clone that has been in existence for some 50,000 years, researchers have discovered.
The study is published in New Phytologist.
Among the most long-lived of organisms, every plant of the Hawaiian population appears to have been produced by vegetative rather than sexual propagation and can be traced back to a single parent.
Surprisingly, the genetic diversity of the Hawaiian clone is comparable to that detected in populations of S. palustre that do propagate sexually and occur across vaster regions.
"The genetic diversity of populations occurring on small remote islands is typically much lower than that detected in populations of the same species found on continents and on larger, less isolated islands," said Eric Karlin, a professor at Ramapo College in Mahwah, New Jersey, USA.
As the Hawaiian Islands are the most remote high volcanic island system in the world, the comparatively high genetic diversity detected in the Hawaiian population of S. palustre is unusual.
The occurrence of high genetic diversity in a clone was also "quite unexpected" said Professor Karlin.
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High genetic diversity in a remote island population system: sans sex
Eric F. Karlin1, Sara C. Hotchkiss2, Sandra B. Boles3, Hans K. Stenøien4, Kristian Hassel4, Kjell I. Flatberg4, A. Jonathan Shaw3
Article first published online: 21 DEC 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Keywords: allopolyploid; bryophyte; clone; genetic diversity; Hawaii; long-distance dispersal; Sphagnum palustre; vegetative propagation
• It has been proposed that long-distance dispersal of mosses to the Hawaiian Islands rarely occurs and that the Hawaiian population of the allopolyploid peat moss Sphagnum palustre probably resulted from a single dispersal event.
• Here, we used microsatellites to investigate whether the Hawaiian population of the dioicous S. palustre had a single founder and to compare its genetic diversity to that found in populations of S. palustre in other regions.
• The genetic diversity of the Hawaiian population is comparable to that of larger population systems. Several lines of evidence, including a lack of sporophytes and an apparently restricted natural distribution, suggest that sexual reproduction is absent in the Hawaiian plants. In addition, all samples of Hawaiian S. palustre share a genetic trait rare in other populations. Time to most recent ancestor (TMRCA) analysis indicates that the Hawaiian population was probably founded 49–51 kyr ago.
• It appears that all Hawaiian plants of S. palustre descend from a single founder via vegetative propagation. The long-term viability of this clonal population coupled with the development of significant genetic diversity suggests that vegetative propagation in a moss does not necessarily preclude evolutionary success in the long term.