Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antarctica Desv.) |
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Authors: | Mark van de Wouw Peter van Dijk Ad H L Huiskes |
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Institution: | NIOO-KNAW, Unit for Polar Ecology, PO Box 140, 4400 AC Yerseke, The Netherlands |
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Abstract: | Aim To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone. Location Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America. Methods Amplified fragment length polymorphisms (AFLPs) and chloroplast sequences were used to study patterns of genetic diversity in Antarctic hairgrass ( Deschampsia antarctica Desv.) and the genetic relationships between populations over its distribution range. Thirty-eight populations were sampled from a large part of the distribution of D. antarctica , and additionally, herbarium specimens were included for areas from which we could not obtain fresh samples. Results A gradient in AFLP diversity was observed going from the Falklands southwards into the Antarctic. This gradient in diversity was also observed within the Antarctic Peninsula: diversity was lower further south. Diversity in the chloroplast genome of D. antarctica was low. Only three chloroplast haplotypes were found, each with a strong regional distribution. Main conclusions The phylogenetic construction of AFLP marker frequencies in meta-populations of D. antarctica supports a stepping-stone model of colonization, whereby gene flow mainly occurs between neighbouring populations. It is concluded that long-distance gene flow is very limited in D. antarctica . A very low diversity was found in the sub-Antarctic islands in the Indian Ocean, indicating that these populations have experienced a recent evolutionary bottleneck. |
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Keywords: | AFLP Antarctica bottleneck cpDNA phylogeography stepping-stone model sub-Antarctic |
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