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Ploidy level analysis of apomictic Hieracium (Asteraceae) reveal unexpected patterns and variation.

Tyler, Torbjörn LU and Jönsson, Jane LU (2009) In Nordic Journal of Botany 27(6). p.490-502
Abstract
The DNA ploidy level of 673 accessions belonging to 238 species of Hieracium have been analyzed by flow cytometry. 222 of the species were of Scandinavian origin as members of the exclusively apomictic H. sectt. Bifida, Hieracium, Oreadea, Tridentata and Vulgata. For the overwhelming majority of the species, the ploidy level (or chromosme number) has never been investigated before. Approximately 50 % of the Scandinavian species, previously believed to be exclusively triploid, were found to be tetraploid. In addition, two pentaploid samples, viz. H. intermarginatum Johanss. & Sam. from Sweden and H. cf. plumbeum Blytt & Fr. from Germany, were found. Although two or more accessions from geographically remote sites were analyzed for... (More)
The DNA ploidy level of 673 accessions belonging to 238 species of Hieracium have been analyzed by flow cytometry. 222 of the species were of Scandinavian origin as members of the exclusively apomictic H. sectt. Bifida, Hieracium, Oreadea, Tridentata and Vulgata. For the overwhelming majority of the species, the ploidy level (or chromosme number) has never been investigated before. Approximately 50 % of the Scandinavian species, previously believed to be exclusively triploid, were found to be tetraploid. In addition, two pentaploid samples, viz. H. intermarginatum Johanss. & Sam. from Sweden and H. cf. plumbeum Blytt & Fr. from Germany, were found. Although two or more accessions from geographically remote sites were analyzed for approximately 50 % of the Scandinavian species, only 2 (< 2 %) taxonomically undisputed species were found to consist of plants with more than one ploidy level. An intriguing pattern was revealed among Scandinavian members of H. sectt. Bifida and Vulgata when ploidy level and morphometric variation was compared, viz. the most typical or extreme representatives of these sections were found to be exclusively triploid whereas tetraploids dominate among species with intermediate morphology and among species morphologically intermediate between these sections and H. sect. Hieracium. This pattern may indicate that the tetraploids, which tend to have mainly northern distributions, have originated as the result of rare sexual hybridizations between triploid members of different sections, plausibly during or after the northward migration of the parental linages after the last glaciation. The results are believed to be highly relevant for understanding the processes of evolution and speciation within the predominantly apomictic genus Hieracium, but it is emphazised that additional data from e.g. molecular markers and pollen viability analysis are needed before any trustworthy conclusions can be made as far as evolutionary processes are concerned. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Nordic Journal of Botany
volume
27
issue
6
pages
490 - 502
publisher
Board of the Nordic Journal of Botany
external identifiers
  • wos:000272660200011
  • scopus:73449137239
ISSN
0107-055X
DOI
10.1111/j.1756-1051.2009.00476.x
language
English
LU publication?
yes
id
c266ed13-eb44-4a29-92b2-512d79301623 (old id 1528586)
alternative location
http://www3.interscience.wiley.com/cgi-bin/fulltext/122672927/PDFSTART
date added to LUP
2010-01-15 12:31:38
date last changed
2017-06-18 03:32:34
@article{c266ed13-eb44-4a29-92b2-512d79301623,
  abstract     = {The DNA ploidy level of 673 accessions belonging to 238 species of Hieracium have been analyzed by flow cytometry. 222 of the species were of Scandinavian origin as members of the exclusively apomictic H. sectt. Bifida, Hieracium, Oreadea, Tridentata and Vulgata. For the overwhelming majority of the species, the ploidy level (or chromosme number) has never been investigated before. Approximately 50 % of the Scandinavian species, previously believed to be exclusively triploid, were found to be tetraploid. In addition, two pentaploid samples, viz. H. intermarginatum Johanss. &amp; Sam. from Sweden and H. cf. plumbeum Blytt &amp; Fr. from Germany, were found. Although two or more accessions from geographically remote sites were analyzed for approximately 50 % of the Scandinavian species, only 2 (&lt; 2 %) taxonomically undisputed species were found to consist of plants with more than one ploidy level. An intriguing pattern was revealed among Scandinavian members of H. sectt. Bifida and Vulgata when ploidy level and morphometric variation was compared, viz. the most typical or extreme representatives of these sections were found to be exclusively triploid whereas tetraploids dominate among species with intermediate morphology and among species morphologically intermediate between these sections and H. sect. Hieracium. This pattern may indicate that the tetraploids, which tend to have mainly northern distributions, have originated as the result of rare sexual hybridizations between triploid members of different sections, plausibly during or after the northward migration of the parental linages after the last glaciation. The results are believed to be highly relevant for understanding the processes of evolution and speciation within the predominantly apomictic genus Hieracium, but it is emphazised that additional data from e.g. molecular markers and pollen viability analysis are needed before any trustworthy conclusions can be made as far as evolutionary processes are concerned.},
  author       = {Tyler, Torbjörn and Jönsson, Jane},
  issn         = {0107-055X},
  language     = {eng},
  number       = {6},
  pages        = {490--502},
  publisher    = {Board of the Nordic Journal of Botany},
  series       = {Nordic Journal of Botany},
  title        = {Ploidy level analysis of apomictic Hieracium (Asteraceae) reveal unexpected patterns and variation.},
  url          = {http://dx.doi.org/10.1111/j.1756-1051.2009.00476.x},
  volume       = {27},
  year         = {2009},
}