Vicariance, long-distance dispersal, and regional extinction-recolonization dynamics explain the disjunct circumpolar distribution of the arctic-alpine plant Silene acaulis.

Premise Of The Study: Many arctic-alpine species have vast geographic ranges, but these may encompass substantial gaps whose origins are poorly understood. Here we address the phylogeographic history of Silene acaulis, a perennial cushion plant with a circumpolar distribution except for a large gap in Siberia.

Methods: We assessed genetic variation in a range-wide sample of 103 populations using plastid DNA (pDNA) sequences and AFLPs (amplified fragment length polymorphisms).

Arctic plant origins and early formation of circumarctic distributions: a case study of the mountain sorrel, Oxyria digyna.

Many plant species comprising the present-day Arctic flora are thought to have originated in the high mountains of North America and Eurasia, migrated northwards as global temperatures fell during the late Tertiary period, and thereafter attained a circumarctic distribution. However, supporting evidence for this hypothesis that provides a temporal framework for the origin, spread and initial attainment of a circumarctic distribution by an arctic plant is currently lacking. Here we examined the origin and initial formation of a circumarctic distribution of the arctic mountain sorrel (Oxyria digyna) by conducting a phylogeographic analysis of plastid and nuclear gene DNA variation.

Rapid radiation and dispersal out of the Qinghai-Tibetan Plateau of an alpine plant lineage Rhodiola (Crassulaceae).

Rhodiola L. (Crassulaceae) is a mid-sized plant genus consisting of about 70 species, with most species distributed on the Qinghai-Tibetan Plateau (QTP) and the adjacent areas, and several species in north-east Asia, Europe, and North America. This study explored the origin and diversification history of Rhodiola and tested the biogeographic relationships between the QTP and other regions of the Northern Hemisphere.

The impact of Pleistocene climate change on an ancient arctic-alpine plant: multiple lineages of disparate history in Oxyria digyna.

The ranges of arctic-alpine species have shifted extensively with Pleistocene climate changes and glaciations. Using sequence data from the trnH-psbA and trnT-trnL chloroplast DNA spacer regions, we investigated the phylogeography of the widespread, ancient (>3 million years) arctic-alpine plant Oxyria digyna (Polygonaceae). We identified 45 haplotypes and six highly divergent major lineages; estimated ages of these lineages (time to most recent common ancestor, T(MRCA)) ranged from ∼0.

Relative reproductive effort in males and females of the dioecious shrub Oemleria cerasiformis.

We derived an index of reproductive effort (g reproductive tissue per g leaf) from data collected over two seasons on 28 males and 28 females of the dioecious shrub Oemleria cerasiformis. Males produced an average of three times as much flower and flower-stalk tissue as females, but because of their large fruits, females produced four times as much total reproductive biomass. Reproductive effort of both sexes was related to light.