Recent Topics Posters
Karlin, Eric F. .
High genetic diversity in a remote island population system: sans sex.
Long distance dispersal of mosses to highly remote islands is thought to be a rare occurrence. Thus the presence of a moss species on the Island of Hawaii is most likely the result of a single dispersal event. The widespread allopolyploid Sphagnum palustre is indigenous to the Island of Hawaii, where its natural distribution is limited to Kohala Mountain. As the plant has been detected in 23,900 yr-old peat from Kohala Mountain and volcanism there ceased about 120,000 years ago, the population was likely founded between these dates. Given the assumption that the Hawaiian population of the dioicous S. palustre is based upon a single dispersal event involving one diaspore, then population growth has been based solely on vegetative propagation. The absence of sporophytes in Hawaiian plants supports this possibility. Fifty-four allodiploid gametophytes of S. palustre collected from eight Hawaiiansites were screened for 16 microsatellite markers to determine regional genetic diversity and to see if there was genetic evidence for a single founding event. Comparisons with microsatellite data from populations of S. palustre and the closely related S. cristatum from other regions show that all Hawaiian plants share a genetic trait that is rare in other populations. Hawaiian plants have one allele per individual at marker 30, while 99% (97/98) of plants from other regions have two alleles per individual at that marker. This strongly supports the occurrence of a single founding event for the Hawaiian population system. Assuming only vegetative reproduction, the time to the most recent ancestor (TMRCA) for the most divergent haplotypes detected among the Hawaiian plants is 24,000 - 28,000 years to 120,000 - 140,000 years (based upon generation times of 1 and 5 years, respectively); this fits within the time frame established above. The genetic diversity detected in the Hawaiian samples is much higher than that detected in S.palustre in western North America (based on preliminary data) and much lower than that detected for S. palustre in eastern North America. It is comparable to, but slightly less than, the genetic diversity detected in S. cristatum on South Island, New Zealand, an island almost 15 times larger than the Island of Hawaii. Although essentially a clone, Hawaiian S. palustre has persisted for a period of time sufficient to generate a population system with a comparably high genetic diversity.
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1 - Ramapo College, Environmental Science, 505 Ramapo Valley Raod, Mahwah, NJ, 07430-1680, USA
Presentation Type: Recent Topics Poster
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM