Tieyao Tu

Dispersals of Hyoscyameae and Mandragoreae (Solanaceae) from the New World to Eurasia in the early Miocene and their biogeographic diversification within Eurasia

The cosmopolitan Solanaceae contains 21 tribes and has the greatest diversity in South America. Hyoscyameae and Mandragoreae are the only tribes of this family distributed exclusively in Eurasia with two centers of diversity: the Mediterranean-Turanian (MT) region and the Tibetan Plateau (TP). In this study, we examined the origins and biogeographical diversifications of the two tribes based on the phylogenetic framework and chronogram inferred from a combined data set of six plastid DNA regions (the atpB gene, the ndhF gene, the rps16-trnK intergenic spacer, the rbcL gene, the trnC-psbM region and the psbA-trnH intergenic spacer) with two fossil calibration points. Our data suggest that Hyoscyameae and Mandragoreae each forms a monophyletic group independently derived from different New World lineages in the early Miocene. Phylogenetic relationships within both tribes are generally well resolved. All genera of Hyoscyameae are found to be monophyletic and they diversified in middle to late Miocene. At nearly the same time, Mandragoreae split into two clades, corresponding to the MT region and the TP region, respectively. Both the phylogenetic relationships and the estimated ages of Hyoscyameae and Mandragoreae support two independent dispersal events of their ancestors from the New World into Eurasia. After their arrivals in Eurasia, the two tribes diversified primarily in the MT region and in the TP region via multiple biogeographic processes including vicariance, dispersal, recolonization or being preserved as relicts, from the mid Miocene to the late Quaternary.

Phylogeny of Nolana (Solanaceae) of the Atacama and Peruvian deserts inferred from sequences of four plastid markers and the nuclear LEAFY second intron

The phylogeny of Nolana (Solanaceae), a genus primarily distributed in the coastal Atacama and Peruvian deserts with a few species in the Andes and one species endemic to the Galápagos Islands, was reconstructed using sequences of four plastid regions (ndhF, psbA-trnH, rps16-trnK and trnC-psbM) and the nuclear LEAFY second intron. The monophyly of Nolana was strongly supported by all molecular data. The LEAFY data suggested that the Chilean species, including Nolana sessiliflora, the N. acuminata group and at least some members of the Alona group, are basally diverged, supporting the Chilean origin of the genus. Three well-supported clades in the LEAFY tree were corroborated by the SINE (short interspersed elements) or SINE-like insertions. Taxa from Peru are grouped roughly into two clades. Nolana galapagensis from the Galápagos Island is most likely to have derived from a Peruvian ancestor. The monophyly of the morphologically well-diagnosed Nolana acuminata group (N. acuminata, N. baccata, N. paradoxa, N. parviflora, N. pterocarpa, N. rupicola and N. elegans) was supported by both plastid and LEAFY data. Incongruence between the plastid and the LEAFY data was detected concerning primarily the positions of N. sessiliflora, N. galapagensis, taxa of the Alona group and the two Peruvian clades. Such incongruence may be due to reticulate evolution or in some cases lineage sorting of plastid DNA. Incongruence between our previous GBSSI trees and the plastid-LEAFY trees was also detected concerning two well-supported major clades in the GBSSI tree. Duplication of the GBSSI gene may have contributed to this incongruence.

Phylogeny of Nolana (Nolaneae, Solanoideae, Solanaceae) as inferred from granule-bound starch synthase I (GBSSI) sequences

The phylogenetic relationships of Nolana (Nolaneae, Solanaceae) were constructed using partial sequences (ca. 891 bp) of the granule-bound starch synthase I (GBSSI) or the waxy gene. Nolana, with 89 species, is primarily distributed in coastal Chile (49 spp.) and Peru (43 spp.), and of these, four species are recorded in Peru and Chile, and another from the Galapagos Islands, Ecuador. Our phylogenetic analysis, utilizing a sampling of 63 of the 89 species, supports the monophyly of Nolana and recovered three clades with 95%-100% bootstrap support. Nolana sessiliflora is the sister taxon to the remainder of the genus. Two large, highly supported clades are evident; one containing taxa from Chile, Peru and the Galapagos Islands, and another containing taxa from Chile and Peru. Nolana galapagensis, an endemic to the Galapagos Islands, is suggested to be sister to N. arenicola in a clade that also includes N. adansonii from southern Peru and northern Chile. These two species differ substantially in habitat preference, habit, leaf shape, and mericarp morphology. The monophyly is confirmed for a morphologically cohesive group composed of N. acuminata, N. baccata, N. elegans, N. reichei, N. parviflora, N. pterocarpa, and N. paradoxa, a clade of essentially Chilean species.

Phylogeographic study of Mandragora L. reveals a case of ancient human assisted migration

In reconstructing taxon evolution, historical biogeography is concerned with two kinds of speciation events, both resulting in a fragmented taxon distribution - vicariance and dispersal. We used PCR-RFLP of plastid DNA and a ribosomal internal transcribed spacer, sequencing of the rps16-trnK chloroplast region, flow cytometry (florescence-activated cell sorter; FACS), and ecological niche modeling to understand the role of these two processes in a disjunct distribution of genus Mandragora. The observed phylogeographic structure only partly coincided with currently recognized species. Commonly used recognition of a single species in the whole Mediterranean is not supported, given that a single haplotype observed from Morocco and Spain to Turkey is strikingly different from the haplotypes found in Israel. In the Sino-Himalayan area, the previously recognized M. chinghaiensis is nested within the M. caulescens clade indicating a very recent diversification within this lineage. And, most importantly, the obtained minimum spanning tree, observed haplotype distribution, and results of FACS call into question the existence of M. turkomanica as a species, and even as a lower taxonomic unit. Rather, the mandrake from Central Asia is nested within those from Israel, suggesting their closely related evolutionary history and ancient human assisted migration from Israel to Persia in historic times. Our study suggests that human assisted migration can explain the cases of disjunct species distribution for which vicariance was previously considered as the only plausible explanation.

Re-establishment of the genus Ania Lindl. (Orchidaceae).

Ania Lindl. is a small genus of the tribe Collabieae subtribe Collabiinae (Orchidaceae). For the last 150 years, it has generally been treated as a synonym of Tainia Blume. In this study, we critically re-examined morphological characters that have been used to distinguish Ania from Tainia, and assessed the phylogeny of Tainia using morphological and palynological characters. Sequences of the nuclear ribosomal ITS, chloroplast trnL intron and combined DNA data sets were analysed to clarify the delimitation and the phylogeny of these groups. The morphological and palynological survey revealed a number of useful diagnostic characters which permit a clear definition of Ania, after the exclusion of a single taxonomically questionable species. Results confirmed that Ania is distinct from Tainia. Phylogenetic reconstructions based on molecular data provided the greatest resolution and produced a morphologically well differentiated clade of Ania. In addition to morphological and suggested palynological characters, the phylogenies were also supported by karyological evidence. Our results support the independent generic status of Ania. The genus name Ania is revived and re-established.

Phylogenetic position of Guihaiothamnus (Rubiaceae): Its evolutionary and ecological implications

Guihaiothamnus (Rubiaceae) is an enigmatic, monotypic genus endemic to southwestern China. Its generic status has never been doubted because it is morphologically unique by having rosette habit, showy, long-corolla-tubed flowers, and multi-seeded indehiscent berry-like fruits. The genus has been postulated to be a relict in the broad-leaved forests of China, and to be related to the genus Wendlandia, which was placed in the subfamily Cinchonoideae and recently classified in the tribe Augusteae of the subfamily Dialypetalanthoideae. Using combined evidence from palynology, cytology, and DNA sequences of nuclear ITS and four plastid markers (rps16, trnT-F, ndhF, rbcL), we assessed the phylogenetic position of Guihaiothamnus in Rubiaceae. Our molecular phylogenetic analyses placed the genus deeply nested within Wendlandia. This relationship is corroborated by evidence from palynology and cytology. Using a relaxed molecular clock method based on five fossil records, we dated the stem age of Wendlandia to be 17.46 my and, the split between G. acaulis and related Wendlandia species in southwestern China to be 2.11mya. This young age, coupled with the derived position in Wendlandia, suggests an evolutionary derivation rather than an evolutionary relict of G. acaulis. Its rosette habit and large showy flowers, which are very distinctive from other Wendlandias, are interpreted as a result of recent rapid adaptation to rock and cliff habitats.

Revised phylogeny and historical biogeography of the cosmopolitan aquatic plant genus Typha (Typhaceae)

Typha is a cosmopolitan aquatic plant genus that includes species with widespread distributions. It is a relatively ancient genus with an abundant fossil record dating back to the Paleogene. However, the details of its biogeographic history have remained unclear until now. In this study, we present a revised molecular phylogeny using sequences of seven chloroplast DNA markers from nine species sampled from various regions in order to infer the biogeographic history of the genus. Two clades were recovered with robust support. Typha minima and T. elephantina comprised one clade, and the other clade included the remaining seven species, which represented a polytomy of four robustly supported subclades. Two widespread species, T. angustifolia and T. domingensis, were revealed to be paraphyletic, indicating the need for taxonomic revision. Divergence time estimation suggested that Typha had a mid-Eocene crown origin, and its diversification occurred in the Middle and Late Miocene. Ancestral area reconstruction showed that Typha possibly originated from eastern Eurasia. Both dispersal via the Beringian Land Bridge and recent transoceanic dispersal may have influenced the intercontinental distribution of Typha species.

Evolutionary history and biogeography of Mandragora L. (Solanaceae)

Mandragora L. (Solanaceae) is the only genus of the tribe Mandragoreae, one of the two tribes of the cosmopolitan nightshade family, which occur exclusively in Eurasia and northern Africa. The genus occurs discontinuously in the Mediterranean region, Turanian region, and on the Tibetan Plateau, representing a classical disjunction pattern in the biogeography of the Old World flora. In this study, we reconstructed the genus phylogeny using AFLP, eight plastid DNA regions and one nuclear (ITS) gene, and evaluated the taxonomic value of quantitative traits time to flowering, fruit and seed size. We also analyzed the evolutionary history of the genus based on a phylogenetic framework and dating inferred from a combined data set of seven plastid regions with one fossil calibration point. Our data suggest that Mandragora originated in the Eocene, apparently along the Tethyan coast in broadleaf deciduous mesophytic forests that covered most of the Mediterranean region at that time. The Mediterranean-Turanian clade diverged from the Tibetan Plateau clade about 20.5 million years ago (Ma) as a result of the plateau uplift which probably was enhanced by aridification in the interior of Eurasia. A second split within the genus occurred about 11.1 Ma and resulted in Western Mediterranean and Near East-Turanian clades. Mandragora turcomanica was found to have very closely related evolutionary history with plants from the Near East indicating a possible ancient human assisted migration from Israel to Persia in historic times. In the Tibetan Plateau area, the morphologically distinctive M. chinghaiensis is nested within the M. caulescens clade indicating a very recent diversification within this lineage.

DNA barcoding the flowering plants from the tropical coral islands of Xisha (China)

Abstract Aim DNA barcoding has been widely applied to species diversity assessment in various ecosystems, including temperate forests, subtropical forests, and tropical rain forests. However, tropical coral islands have never been barcoded before due to the difficulties in field exploring. This study aims at barcoding the flowering plants from a unique ecosystem of the tropical coral islands in the Pacific Ocean and supplying valuable evolutionary information for better understanding plant community assembly of those particular islands in the future. Location Xisha Islands, China. Methods This study built a DNA barcode database for 155 plant species from the Xisha Islands using three DNA markers (ITS, rbcL, and matK). We applied the sequence similarity method and a phylogenetic‐based method to assess the barcoding resolution. Results All the three DNA barcodes showed high levels of PCR success (96%–99%) and sequencing success (98%–100%). ITS performed the highest rate of species resolution (>95%) among the three markers, while plastid markers delivered a relatively poor species resolution (85%–90%). Our analyses obtained a marginal increase in species resolution when combining the three DNA barcodes. Main conclusions This study provides the first plant DNA barcode data for the unique ecosystem of tropical coral islands and considerably supplements the DNA barcode library for the flowering plants on the oceanic islands. Based on the PCR and sequencing success rates, and the discriminatory power of the three DNA regions, we recommend ITS as the most successful DNA barcode to identify the flowering plants from Xisha Islands. Due to its high sequence variation and low fungal contamination, ITS could be a preferable candidate of DNA barcode for plants from other tropical coral islands as well. Our results also shed lights on the importance of biodiversity conservation of tropical coral islands.

A karyological study of Suriana maritima L. (Surianaceae) from Xisha Islands of South China Sea

Abstract The present paper deals with the detailed cytological study of Suriana maritima L. (Surianaceae) from the Xisha Islands (also known as Paracel Islands) of South China Sea. The somatic chromosome number of the species is 18 and the karyotype formula is 2n = 2x = 18 m. The interphase nucleus is classified as round prochromosome. This is the first karyological investigation in Surianaceae, and the results provide new insights into the cytological characteristics of the plant family.