Historical biogeography of a Brazilian lineage of Tillandsioideae (subtribe Vrieseinae, Bromeliaceae): the Paranaean Sea hypothesized as the main vicariant event

Subtribe Vrieseinae comprise four genera, Alcantarea, Stigmatodon, Vriesea s.s. and Waltillia, encompassing c. 20% of species in Tillandsioideae (Bromeliaceae), almost all of which are exclusive to Brazil. Here, we explore the biogeographic history of Vrieseinae, sampling 21 of the 22 genera of Tillandsioideae (130 terminals) and three DNA sequence markers (two plastid: rps16-trnK and matK; one nuclear: PHYC). We inferred a dated phylogeny and the ancestral areas of this lineage through RASP (reconstruct ancestral state in phylogeny) analyses. Vrieseinae were recovered as monophyletic, but tribe Vrieseeae (subtribe Vrieseinae + subtribe Cipuropsidinae) were not. A vicariant event between the Andes and Brazilian Shield probably occurred c. 10 Mya, when two clades, Cipuropsidineae + Tillandsieae and Vrieseineae, diverged. The Atlantic Forest plus the Chacoan region is recognized as the ancestral area for Vrieseinae. The results confirmed the recent origin of genera of Vrieseinae, with estimated crown ages in the Pliocene (5.3–2.6 Mya). We propose that the Paranaean Sea influenced the divergence of the main clades; Pleistocene events were probably responsible for the diversification of the most recent clades. This study sheds light on the biogeographic history of a key group of Neotropical plants, providing a new hypothesis for the evolution of bromeliads.

Revision of Muhlenbergia (Poaceae, Chloridoideae, Cynodonteae, Muhlenbergiinae) in Peru: classification, phylogeny, and a new species, M. romaschenkoi

A taxonomic treatment, phylogeny based on analysis of six DNA sequence markers (ITS, ndhA intron, rpl32-trnL, rps3, rps16 intron and rps16-trnK) and classification of Muhlenbergia for Peru is given. Seventeen species and one presumed hybrid are recognised. Muhlenbergiaromaschenkoisp. nov. is newly described from the Río Huallaga Valley, northeast of Huánuco. The type of Podosemumangustatum [≡ Muhlenbergiaangustata] clearly aligns with what we had been referring to as the hybrid between this species and M.rigida. Therefore, we adopt the next available heterotypic name, Muhlenbergiacoerulea, for what we had been calling M.angustata and change the hybrid designation to M.coerulea × M.rigida. Lectotypes are designated for Epicampescoerulea Griseb., Muhlenbergiaaffinis Trin., Muhlenbergiaberlandieri Trin., Muhlenbergiabeyrichiana Kunth, Muhlenbergiaelegansvar.atroviolacea Kuntze, Muhlenbergiaelegansvar.subviridis Kuntze and Muhlenbergiaphragmitoides Griseb.

Comparative dating of Acacia: combining fossils and multiple phylogenies to infer ages of clades with poor fossil records

The ubiquitous and highly diverse element Australian Acacia makes an ideal candidate for investigating a range of questions about the evolution of the flora of continental Australia. In the past, such efforts have been hampered by a lack of well-supported phylogenies and by the relatively poor macrofossil record, which probably reflects the depositional environment in which Acacia species are predominantly found. However, the broader subfamily Mimosoideae offers several reliably age-constrained fossils that can be used as calibrations in divergence-dating analyses of DNA sequence data. In addition, the microfossil pollen record of Acacia is relatively rich and provides a good age constraint for the entire Acacia clade. By using multiple reliable fossil constraints, we applied a combination of primary calibration points to produce a comprehensive study of divergence dates in Acacia s.s. and related mimosoid legumes. Previous dating studies included very limited samples of the diversity of Australian Acacia and experienced difficulties in identifying appropriate age calibrations for the lineage, leading to considerable variation in their results. We used novel calibration schemes and multiple nuclear and chloroplast DNA sequence markers to produce the first estimates of divergence dates for major lineages within the Australian Acacia s.s. clade and for related lineages across the Mimosoideae subfamily. We estimate average crown divergence dates for Vachellia at 13–17 Ma, Senegalia at 31.0–33.4 Ma and Acacia s.s. at 21.0–23.9 Ma. The timing of radiations within these lineages is consistent with the hypothesis that Miocene aridification in Africa, the Americas and Australia was a driver for the diversificationss of lineages in Acacia s.l.

The sponge genetree server—providing a phylogenetic backbone for poriferan evolutionary studies

Unravelling the phylogenetic relationships of sponges (Phylum Porifera) is an important as well as challenging task. It helps the understanding of character evolution among early branching metazoans but also aids in bioprospecting for valuable bioactive sponge compounds. However, the phylogenetic relationships among Porifera are largely unsolved, because the simple poriferan bauplan frequently prevents unambiguous taxonomic species assignment and a clear definition of morphological synapomorphies is difficult (see e.g. Boury-Esnault 2006). DNA sequence markers are frequently employed to overcome morphological shortcomings in phylogeny (e.g. Kelly Borges et al. 1991) and taxonomy (e.g. DNA barcoding, see Wörheide & Erpenbeck 2007). However, some DNA markers suffer from insufficient phylogenetic signal (see e.g. Duran et al. 2004 and Wörheide 2006 on CO1 in population studies) and unequal evolutionary rates among taxa (see e.g. Erpenbeck et al. 2004 on 28S in Haplosclerida). Therefore, a careful evaluation and selection of molecular markers for each individual project is required.