Systematics Section / ASPT
Scheen, Anne-Cathrine , Brochmann, Christian , Brysting, Anne K. , Elven, Reidar , Morris, Ashley B. , Soltis, Douglas E. , Soltis, Pamela S. , Albert, Victor A. .
Northern hemisphere biogeography of Cerastium (Caryophyllaceae): insights from phylogenetic analysis of non coding plastid nucleotide sequences.
Phylogenetic relationships and biogeography of the genus Cerastium were studied using sequences of three noncoding plastid DNA regions (trnL intron, trnL-trnF spacer, and psbA-trnH spacer). A total of 57 Cerastium taxa was analyzed using two species of the putative sister genus Stellaria as outgroups. Maximum parsimony analyses identified four clades that largely corresponded to previously recognized infrageneric groups. The results suggest an Old World origin and at least two migration events into North America from the Old World. The first event possibly took place across the Bering land bridge during the Miocene. Subsequent colonization of South America occurred after the North and South American continents joined during the Pliocene. A more recent migration event into North America probably across the northern Atlantic took place during the Quaternary, resulting in the current circumpolar distribution of the Arctic species. Molecular clock dating of major biogeographic events was internally consistent on the phylogenetic trees. The arctic high-polyploid species form a polytomy together with some boreal and temperate species of the C. tomentosum group and the C. arvense group. Lack of genetic variation among the arctic species probably indicates a recent origin. The annual life form is shown to be of polyphyletic origin.
1 - University of Florida, Department of Natural History, Florida Museum of Natural History, P.O. Box 117800, Gainesville, Florida, 32611-7800, USA
2 - University of Florida, Department of Botany, 220 Bartram Hall, P.O. Box 118526, Gainesville, Florida, 32611-8526, USA
3 - University of Oslo, Natural History Museums and Botanical Garden, NCB - National Centre for Biosystematics, P.O. Box 1172, Blindern, Oslo, NO-0318, Norway
4 - University of Oslo, Botanical Garden, Natural History Museums and Botanical Garden, P.O. Box 1172 Blindern, Oslo, NO-0318, Norway
Presentation Type: Paper
Location: Cottonwood C (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 2:00 PM