David E. Boufford

Elevational patterns of species richness and endemism for some important taxa in the Hengduan Mountains, southwestern China

We describe the elevational patterns of species richness and endemism of some important taxa in the Hengduan Mountains, southwest China. Species richness data came from publications, an online database, herbaria and field work. Species richness was estimated by rarefaction and interpolation. The Hengduan Mountains region was divided into a southern and northern subregion, and all species were assigned to four groups based on their distributional range within this region. The conditional autoregressive model (CAR) was used to relate species richness and explanatory variables. The elevational patterns of total, endemic and non-endemic species richness, at subregion and entire region scales, presented to be unimodal and peaked at similar elevations. Area size was strongly related with species richness, and was more powerful in explaining variation in species richness in the northern subregion than in the southern subregion. A single climatic variable (mean annual rainfall, potential evapotranspiration or moisture index) showed a weak relationship with the elevational pattern of species richness. Area and climatic variables together explained more than 67% of the variation in non-endemic richness, 53% in total richness, and 50% in endemic richness. There were three patterns of endemism at the generic level with increasing elevation: namely endemism increased, decreased, or peaked at middle elevations. All selected taxa have experienced rapid speciation and evolution within this region, which plays an important role in the uniform elevational patterns of total, endemic and non-endemic richness, and in the multiform elevational patterns of endemism.

Seed plant endemism on Hainan Island: a framework for conservation actions.

Hainan, the second largest island of China, has the most extensive and best preserved tropical forests of this country. A network of 68 protected areas (54 of them are terrestrial) provides in situ conservation for the unique ecosystems of the island. We: (1) discuss an updated check-list of seed-plant species that are endemic to Hainan, (2) evaluate the extent to which the endemic flora has been the subject of molecular studies, and (3) investigate the conservation status of these species. We recognize 397 endemic species on the island, 271 of which are reported in the protected areas, and 144 of which have been Red-Listed (85 assigned to the Critically Endangered (40) or Endangered (45) IUCN categories). The families with the highest number of endemics are Rubiaceae (33 species), Lauraceae (27 species), and Poaceae (26 species). The island has only seven endemic genera, all of which are unispecific. Compared with other tropical islands, Hainan has a low number of endemics but our preliminary observations suggest that the island has a highly disharmonic flora when compared with that from the mainland. Nevertheless, most of the major clades of the seed-plant tree of life with representatives in China also have endemic species on the island. We argue that the low levels of endemism reflect the continental nature of Hainan and the fact that several areas of the island have not been fully inventoried. We were unable to find a single molecular systematic study focusing exclusively on the Hainan endemics; however, 24 of the endemic species have been included in phylogenetic studies targeting particular genera or families. Future research/conservation actions for the endemic flora of Hainan should focus in developing: (1) a red-list that assesses all 397 endemic species, (2) comprehensive floristic studies for the protected areas, (3) molecular phylogenetic and conservation genetic studies with a primary focus on the endemics, (4) studies to understand what ecological interactions are important in the biology of the endemic species, and (5) eco-geographical studies to identify Important Biodiversity Zones of endemism within Hainan and therefore potential new protected areas.

Testing a hypothesis of unidirectional hybridization in plants: Observations on Sonneratia, Bruguiera and Ligularia

BackgroundWhen natural hybridization occurs at sites where the hybridizing species differ in abundance, the pollen load delivered to the rare species should be predominantly from the common species. Previous authors have therefore proposed a hypothesis on the direction of hybridization: interspecific hybrids are more likely to have the female parent from the rare species and the male parent from the common species. We wish to test this hypothesis using data of plant hybridizations both from our own experimentation and from the literature.ResultsBy examining the maternally inherited chloroplast DNA of 6 cases of F1 hybridization from four genera of plants, we infer unidirectional hybridization in most cases. In all 5 cases where the relative abundance of the parental species deviates from parity, however, the direction is predominantly in the direction opposite of the prediction based strictly on numerical abundance.ConclusionOur results show that the observed direction of hybridization is almost always opposite of the predicted direction based on the relative abundance of the hybridizing species. Several alternative hypotheses, including unidirectional postmating isolation and reinforcement of premating isolation, were discussed.

Phylogeny of the Altingiaceae based on cpDNA matK, PY-IGS and nrDNA ITS sequences

Abstract. Phylogenetic relationships of the three genera of the family Altingiaceae, i.e., Altingia, Liquidambar and Semiliquidambar, based on matK sequences and the intergenic spacer between the psaA and ycf3 genes (PY-IGS) of cpDNA, and on the internal transcribed spacer (ITS) of nrDNA were studied. Phylogenetic trees based on the three data sets (matK, PY-IGS and ITS) were generated using Hamamelis japonica and Mytilaria laosensis (Hamamelidaceae), Cercidiphyllum japonicum (Cercidiphyllaceae), and Daphniphyllum calycinum (Daphniphyllaceae) as outgroups. The partition-homogeneity tests indicated that the three data sets and the combined data are homogeneous. A combined analysis also generated a strongly supported phylogeny. The phylogenetic trees show that the North American and western Asian species, L. styraciflua and L. orientalis, respectively, form a monophyletic group which is sister to the clade including all Asian species in the family. The genus Liquidambar is paraphyletic with Altingia and Semiliquidambar nested within. Phylogenetic analyses of the molecular data indicate that taxonomic reexamination of the generic delimitation in the Altingiaceae is needed.

Adaptive evolution of rbcL in Conocephalum (Hepaticae, bryophytes)

An excess of nonsynonymous substitutions over synonymous ones has been regarded as an important indicator of adaptive evolution or positive selection at the molecular level. We now report such a case for rbcL sequences among cryptic species in Conocephalum (Hepaticae, Bryophytes). This finding can be regarded as evidence of adaptive evolution in several cryptic species (especially in F and JN types) within the genus. Bryophytes are small land plants with simple morphology. We can therefore expect the existence of several biologically distinct units or cryptic species within each morphological species. In our previous study, we found three rbcL types in Asian Conocephalum japonicum (Thunb.) Grolle and also found evidence strongly suggesting that the three types are reproductively isolated cryptic species. Additionally, we examined rbcL sequence variation in six cryptic species of C. conicum (L.) Dumort. previously recognized by allozyme analyses. As a result, we were able to discriminate the six cryptic species based only on their rbcL sequences. We were able to show that rbcL sequence variation is also useful in finding cryptic species of C. conicum.

Phylogenetic Analysis of the Sonneratiaceae and its Relationship to Lythraceae Based on ITS Sequences of nrDNA

Lagerstroemia nested within the Sonneratiaceae. The Sonneratiaceae occurred within the Lythraceae with high bootstrap value support (96%). The two traditional genera constituting Sonneratiaceae were in different well-supported clades. Duabanga (Sonneratiaceae) is sister to the clade of Lagerstroemia (Lythraceae) (82%). The mangrove genus Sonneratia (100%) formed the other monophyletic group. It was located terminally within the Lythraceae clade and comprised two clades: one consisting of S. apetala, S. alba, S. ovata, and S. hainanensis; the other including S. caseolaris and S. paracaseolaris. The results indicated that species previously placed in two different sections (Sect. Sonneratia and Sect. Pseudosonneratia) of Sonneratia occurred within the same clade, and the taxonomic classification was not supported by the molecular analysis of the ITS region sequences. Based on the phylogenetic analyses of the ITS regions, the Sonneratiaceae were shown to be nested within the family Lythraceae. Therefore, the sequence data presented here do not support the recognition of the Sonneratiaceae as a distinct family, but instead support the inclusion of Sonneratiaceae in the Lythraceae proposed by other authors.

Phylogenetic relationships of the Magnoliaceae inferred from cpDNA matK sequences

Abstract The coding region of the matK gene was sequenced to infer the phylogeny of the family Magnoliaceae. Phylogenetic analyses of 21 matK sequences representing ten genera of Magnoliaceae and three outgroups suggest relationships among both subfamilies and genera. Monophyly of the subfamily Liriodendroideae (the genus Liriodendron) and the subfamily Magnolioideae is strongly supported, respectively. Within the subfamily Magnolioideae, three clades are formed: (1) the genus Magnlietia, (2) the subgenus Magnolia, and (3) the subgenus Yulania, with the genera Michelia, Paramichelia, Tsoongiodendron, Alcimandra, Kmeria, Parakmeria and Manglietiastrum. However, the genus Magnolia is shown to be a polyphyletic group, and the genus Michelia a paraphyletic group. Relatively low sequence divergences are detected among genera of the the subfamily Magnolioideae, ranging from 0.14% to 1.70%, especially in the tribe Micheliinae (0.14–0.98%). Molecular evidence from matK sequence data suggests that the phylogenetic positions and the delimitation of the eight genera Magnolia, Michelia, Tsoongiodendron, Paramichelia, Alcimandra, Kmeria, Parakmeria and Manglietiastrum need to be reconsidered.

A CLADISTIC ANALYSIS OF CIRCAEA (ONAGRACEAE)

Abstract— Circaea (Onagraceae), a genus of seven species from the northern hemisphere, forms a monophylctic group defined by the following synapomorphies: two stamens (opposite the sepals), fruits indehiscent capsules, hooked hairs on the fruits, and perianth parts reduced to two. A cladistic analysis of the genus was performed using 22 characters from morphology, anatomy and palynology. The seven species and seven additional subspecies were considered the terminal taxa. Polarity of the characters is based on the outgroup comparison method. Eighteen equally parsimonious cladograms were produced, each with 32 steps and a consistency index of 0.75. A successive weighting procedure was applied, resulting in six cladograms with a consistency index of 0.95. All 24 cladograms share the following seven monophylctic groups: (1) all species except C. cordala and C. glabrescens (stipules deciduous); (2) the group of C. mollis, the three subspecies of C. lutetiana and C. erubescens (exsertcd nectary); (3) C. repens and all six subspecies of C. alpina (single‐seeded fruits, stolons terminated by tubers, and viscin threads reduced or absent); (4) the six subspecies of C. alpina (unilocular ovaries with no trace of a second loculc and tardily opening perianth); (5) C. alpina subspecies alpina, micrantha, pacifica, and imaicola (flowers opening on ascending to erect pedicels); (6) C. alpina subspecies alpina, micrantha, and pacifica (translucent leaves); (7) C. alpina subspecies alpina and murantha (glabrous stems). Results of the cladistic analysis support most of the current systematic classification of the genus, except for the relationships among the three subspecies of C. lutetiana.

Why Are We Still Producing Paper Floras?1

Abstract Advances in online resources and electronic publication provide the sciences with tools to revolutionize education and research (e.g., cataloging, data archiving and access, and identification). Older journals and monographs are being scanned and increasingly posted online quickly by book scanning projects, although even for new issues, there can be a “moving wall” or lag time (e.g., BioOne and JSTOR). Some scientific disciplines are providing the public with pre-print access to articles in digital libraries, while manuscript availability in other disciplines, such as nomenclatural botany, is often delayed until the time of print publication. Within botany, taxonomic treatments should be provided online at all stages of preparation and revision (in certain cases following initial editing). Now, many published floras can be browsed and searched online (e.g., Flora of North America, Jepson Manual, Flora of Australia). The Flora of China Project provides treatments at all stages, online, prior to printing of volumes. Because of this visibility, the Flora of China Web site regularly receives questions from the general public and helpful review comments from botanists worldwide. With pressing issues of cataloging biodiversity, conservation, and sustainable use of resources, botanists are challenged to prepare and revise online treatments, including interactive identification keys and images, for a worldwide audience of students and researchers.

Phylogenetic position of Schnabelia, a genus endemic to China: Evidence from sequences of cpDNA matK gene and nrDNA ITS regions

The chloroplast gene matK and the internal transcribed spacers (ITS) of the nuclear ribosomal DNA fromSchnabelia, a genus endemic to China, and 6 genera of Verbenaceae and 13 genera of Lamiaceae were sequenced. The phylogenetic signal and validity outgroups were measured and evaluated by means of the relatively apparent synapomorphy analysis (RASA). Independent and combined phylogenetic analyses for the matK and ITS sequences were performed using the maximum parsimony (MP), neighborjoining (NJ) and maximum likelihood (ML) methods, indicating thatSchnabelia oligophylla andCaryopteris terniflora form a sister-group relationship. TheCaryopteris complex is not shown to be a monophyly becauseTrichostema, C. paniculata andC. forrestii are paraphyletic to the clade containing the remaining members of the complex. A monophyly of Ajugoideae proposed by Cantino et al., including 8 genera in this study, is strongly supported and the closest relatives ofSchnabelia are in the Ajugoideae (Lamiaceae), especially nearCaryopteris terniflora. The polygenetic analyses also showed that the genera of Lamiaceae and Verbenaceae sampled in this tudy are phylogenetically mixed and the genusAvicennia is distant to other genera of Verbenaceae. RASA and combined analysis can be used as effective approaches to determining the relationships among phylogenetically complex groups.