Systematics Section / ASPT
Fay, Michael F. , Pillon, Yohan , Hedrén, Mikael , Bateman, Richard M , Chase, Mark W. .
Insights into the evolution and biogeography of Western European species complexes in Dactylorhiz (Orchidaceae).
We have used a combination of four plastid DNA fragments and ITS alleles to investigate relationships in the orchid genus Dactylorhiza focusing on the incarnata/maculata polyploid complex, which consists of three groups of species: D. incarnata s.l., D. maculata s.l. and allotetraploids formed by crosses between species in the first two complexes. The combination of the four plastid fragments defined 34 haplotypes and allowed us to distinguish between the different parental taxa of the allotetraploids in most cases. ITS alleles also allowed us to distinguish between these parental taxa. Together these markers demonstrate that D. maculata (a tetraploid) is not derived from the diploid D. fuchsii as previously thought, as it possessed different variants of the plastid and ITS markers. The allotetraploids can be split into two major groups, D. majalis s.l. and D. elata s.l. Members of D. majalis s.l. are derived from D. fuchsii and D. incarnata, whereas members of D. elata s.l. are derived from D. maculata and D. incarnata. Within both groups, conversion of ITS appears to be occurring, and we hypothesize that each contains relatively old allotetraploids in which gene conversion has more or less gone to completion (in most cases in the direction of the D. maculata/D. fuchsii alleles) and relatively young allotetraploids still possessing detectable numbers of copies of each parental allele. Together with our earlier data from enzyme, AFLP and sequencing studies, these markers are leading to a greater understanding of patterns of evolution in this complex group.
1 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey, TW9 3AB, UK
2 - University of Lund, Department of Ecology, Plant Ecology and Systematics, Sölvegatan 37, Lund, SE-223 62, Sweden
3 - Université des Sciences et Technologies de Lille, Lille, , France
4 - Natural History Museum, Department of Botany, Cromwell Road, London, SW7 5BD, United Kingdom
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 11:00 AM