Phylogeny and species delimitation in Silene sect. Arenosae (Caryophyllaceae): a new section.

A putatively monophyletic group of annual Silene species is revised taxonomically and described as the new section S. sect. Arenosae. The species of this section were previously treated as a part of a widely circumscribed and polyphyletic S. sect. Rigidulae. Silene sect. Arenosae as circumscribed here consists of nine species. Members of the section show a predominantly E Mediterranean to SW Asian distribution pattern from Turkey southward to Egypt and eastward to Iran and Pakistan, although most of the species have a limited distribution range. The species of S. sect. Arenosae are characterized by narrowly lanceolate calyx teeth, which are often highly polymorphic, and lanceolate to oblanceolate (non-spathulate) basal leaves. The provided taxonomic revision is based on morphological characters and supported by phylogenetic analyses of two nuclear loci (nrITS and an intron of the RPB2 gene) and one chloroplast locus (the intron of the rps16 gene). The species descriptions are formalized using a novel implementation of the Prometheus Description Model.

Hybrid origins and homoploid reticulate evolution within Heliosperma (Sileneae, Caryophyllaceae)--a multigene phylogenetic approach with relative dating.

We used four potentially unlinked nuclear DNA regions from the gene family encoding the second largest subunit of the RNA polymerases, as well as the psbE-petG spacer and the rps16 intron from the chloroplast genome, to evaluate the origin of and relationships within Heliosperma (Sileneae, Caryophyllaceae). Relative dates of divergence times are used to discriminate between hybridization and gene duplication/loss as alternative explanations for topological conflicts between gene trees. The observed incongruent relationships among the three major lineages of Heliosperma are better explained by homoploid hybridization than by gene duplication/losses because species branching events exceed gene coalescence times under biologically reasonable population sizes and generation times, making lineage sorting an unlikely explanation. The origin of Heliosperma is complex and the gene trees likely reflect both reticulate evolution and sorting events. At least two lineages have been involved in the origin of Heliosperma, one most closely related to the ancestor of Viscaria and Atocion and the other to Eudianthe and/or Petrocoptis.

The origin and number of introductions of the Hawaiian endemic Silene species (Caryophyllaceae).

The Hawaiian endemic Silene are a small group of woody or semiwoody representatives from a large, predominantly herbaceous, species-rich genus. We here investigated the origin and number of introductions of the endemic Hawaiian Silene based on phylogenetic relationships inferred from DNA sequences from both the plastid (the rps16 intron) and the nuclear (ribosomal internal transcribed sequences, ITS, and intron 23 of the RPB2 gene) genomes. Silene antirrhina, a widespread weedy American annual, is strongly supported as sister to a monophyletic group consisting of the Hawaiian Silene, indicating a single colonization event. There are no obvious morphological similarities between S. antirrhina and any of the species of Hawaiian Silene. Our results suggest an American origin for the Hawaiian endemics because that would require only a single trans-ocean dispersal. Two of the Hawaiian endemics (S. struthioloides and S. hawaiiensis) that form a subclade in the analyses have evolved woodiness after introduction to the Hawaiian Islands. Our results contribute to other recent results based on molecular phylogenetics that emphasize the American continent as a source area for the Hawaiian flora and support a striking morphological radiation and evolution of woodiness from a single introduction to the archipelago.