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High levels of genetic diversity in marginal populations of the marsh orchid Dactylorhiza majalis subsp. majalis

Hedrén, Mikael LU and Olofsson, Sofie Nordström LU (2018) In Nordic Journal of Botany 36(4).
Abstract

Because of harsh conditions, suboptimal habitat quality and poor connectivity to other populations, plant populations at the margin of a distribution are expected to be less genetically diverse, but to be more divergent from each other than populations in the centre of a distribution. In northern Europe, northern marginal populations may also be younger than populations further to the south, and may have had less time to accumulate genetic diversity by mutation and gene flow. However, orchids have very small seeds, which are easily dispersed long distances by wind, and orchids are therefore expected to show less differentiation between marginal and central populations than other groups of seed plants. Here, we analysed whether... (More)

Because of harsh conditions, suboptimal habitat quality and poor connectivity to other populations, plant populations at the margin of a distribution are expected to be less genetically diverse, but to be more divergent from each other than populations in the centre of a distribution. In northern Europe, northern marginal populations may also be younger than populations further to the south, and may have had less time to accumulate genetic diversity by mutation and gene flow. However, orchids have very small seeds, which are easily dispersed long distances by wind, and orchids are therefore expected to show less differentiation between marginal and central populations than other groups of seed plants. Here, we analysed whether Scandinavian populations of the tetraploid marsh orchid Dactylorhiza majalis subsp. majalis differ from central European populations in genetic diversity patterns. A total of 220 plants from eight central European and ten Scandinavian populations was examined for variation at five nuclear microsatellite loci, nuclear ITS and 13 polymorphic sites in noncoding regions of the plastid genome. The total genetic diversity was slightly lower in Scandinavia than in central Europe, both in plastid and nuclear markers, but the differences were small. Also, the Scandinavian populations were less diverse and somewhat more strongly differentiated from each other than the central European ones. Dactylorhiza majalis subsp. majalis has apparently colonized Scandinavia on multiple independent occasions and from different source areas in the south. Seed flow between Scandinavian populations has still not fully erased the patterns imprinted by early colonization. Our results suggest that marginal populations of orchids may be as important as central ones in preserving genetic diversity through Pleistocene glacial cycles. We also predict that orchids with their light seeds are better adapted than many other plants to respond to future climate changes by dispersing into new suitable areas.

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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
conservation, Dactylorhiza majalis, genetic diversity, marginal populations, nuclear microsatellites, plastid DNA
in
Nordic Journal of Botany
volume
36
issue
4
publisher
Board of the Nordic Journal of Botany
external identifiers
  • scopus:85046477026
ISSN
0107-055X
DOI
10.1111/njb.01747
language
English
LU publication?
yes
id
752e2d40-9933-4696-bd32-794d171ded2c
date added to LUP
2018-05-17 15:23:47
date last changed
2018-10-03 10:05:12
@article{752e2d40-9933-4696-bd32-794d171ded2c,
  abstract     = {<p>Because of harsh conditions, suboptimal habitat quality and poor connectivity to other populations, plant populations at the margin of a distribution are expected to be less genetically diverse, but to be more divergent from each other than populations in the centre of a distribution. In northern Europe, northern marginal populations may also be younger than populations further to the south, and may have had less time to accumulate genetic diversity by mutation and gene flow. However, orchids have very small seeds, which are easily dispersed long distances by wind, and orchids are therefore expected to show less differentiation between marginal and central populations than other groups of seed plants. Here, we analysed whether Scandinavian populations of the tetraploid marsh orchid Dactylorhiza majalis subsp. majalis differ from central European populations in genetic diversity patterns. A total of 220 plants from eight central European and ten Scandinavian populations was examined for variation at five nuclear microsatellite loci, nuclear ITS and 13 polymorphic sites in noncoding regions of the plastid genome. The total genetic diversity was slightly lower in Scandinavia than in central Europe, both in plastid and nuclear markers, but the differences were small. Also, the Scandinavian populations were less diverse and somewhat more strongly differentiated from each other than the central European ones. Dactylorhiza majalis subsp. majalis has apparently colonized Scandinavia on multiple independent occasions and from different source areas in the south. Seed flow between Scandinavian populations has still not fully erased the patterns imprinted by early colonization. Our results suggest that marginal populations of orchids may be as important as central ones in preserving genetic diversity through Pleistocene glacial cycles. We also predict that orchids with their light seeds are better adapted than many other plants to respond to future climate changes by dispersing into new suitable areas.</p>},
  articleno    = {e01747},
  author       = {Hedrén, Mikael and Olofsson, Sofie Nordström},
  issn         = {0107-055X},
  keyword      = {conservation,Dactylorhiza majalis,genetic diversity,marginal populations,nuclear microsatellites,plastid DNA},
  language     = {eng},
  month        = {04},
  number       = {4},
  publisher    = {Board of the Nordic Journal of Botany},
  series       = {Nordic Journal of Botany},
  title        = {High levels of genetic diversity in marginal populations of the marsh orchid Dactylorhiza majalis subsp. majalis},
  url          = {http://dx.doi.org/10.1111/njb.01747},
  volume       = {36},
  year         = {2018},
}