Pleistocene glaciation advances the cryptic speciation of Stellera chamaejasme L. in a major biodiversity hotspot.

The mountains of Southwest China comprise a significant large mountain range and biodiversity hotspot imperiled by global climate change. The high species diversity in this mountain system has long been attributed to a complex set of factors, and recent large-scale macroevolutionary investigations have placed a broad timeline on plant diversification that stretches from 10 million years ago (Mya) to the present. Despite our increasing understanding of the temporal mode of speciation, finer-scale population-level investigations are lacking to better refine these temporal trends and illuminate the abiotic and biotic influences of cryptic speciation. This is largely due to the dearth of organismal sampling among closely related species and populations, spanning the incredible size and topological heterogeneity of this region. Our study dives into these evolutionary dynamics of speciation using genomic and eco-morphological data of Stellera chamaejasme L. We identified four previously unrecognized cryptic species having indistinct morphological traits and large metapopulation of evolving lineages, suggesting a more recent diversification (~2.67-0.90 Mya), largely influenced by Pleistocene glaciation and biotic factors. These factors likely influenced allopatric speciation and advocated cyclical warming-cooling episodes along elevational gradients during the Pleistocene. The study refines the evolutionary timeline to be much younger than previously implicated and raises the concern that projected future warming may influence the alpine species diversity, necessitating increased conservation efforts.

Global warming pushes the distribution range of the two alpine 'glasshouse' Rheum species north- and upwards in the Eastern Himalayas and the Hengduan Mountains.

Alpine plants' distribution is being pushed higher towards mountaintops due to global warming, finally diminishing their range and thereby increasing the risk of extinction. Plants with specialized 'glasshouse' structures have adapted well to harsh alpine environments, notably to the extremely low temperatures, which makes them vulnerable to global warming. However, their response to global warming is quite unexplored. Therefore, by compiling occurrences and several environmental strata, we utilized multiple ensemble species distribution modeling (eSDM) to estimate the historical, present-day, and future distribution of two alpine 'glasshouse' species Rheum nobile Hook. f. & Thomson and R. alexandrae Batalin. Rheum nobile was predicted to extend its distribution from the Eastern Himalaya (EH) to the Hengduan Mountains (HM), whereas R. alexandrae was restricted exclusively in the HM. Both species witnessed a northward expansion of suitable habitats followed by a southerly retreat in the HM region. Our findings reveal that both species have a considerable range shift under different climate change scenarios, mainly triggered by precipitation rather than temperature. The model predicted northward and upward migration for both species since the last glacial period which is mainly due to expected future climate change scenarios. Further, the observed niche overlap between the two species presented that they are more divergent depending on their habitat, except for certain regions in the HM. However, relocating appropriate habitats to the north and high elevation may not ensure the species' survival, as it needs to adapt to the extreme climatic circumstances in alpine habitats. Therefore, we advocate for more conservation efforts in these biodiversity hotspots.

Saussurea talungensis (Asteraceae), a new species from Humla, Nepal Himalayas.

A new species Saussurea talungensis S.K.Ghimire & H.K.Rana, sp. nov. (sect. Strictae), from Talung valley of Humla district, Nepal, is described and illustrated. Morphologically, this species resembles Saussurea roylei and Saussurea lanata in habit, though it can be distinguished in having longer leaf petioles, purplish leaf margin, 1 or 3 capitula, shorter phyllaries, shorter receptacle bristles and the same anthers, comparatively shorter corolla with shorter lobes. Phylogenomic analysis also supports S. talungensis as a distinct species of Saussurea. Here, we provide taxonomic note, distribution map and phylogenomic inference to distinguish the new species and its allied members.

Molecular phylogeny, biogeography and character evolution of the montane genus Incarvillea Juss. (Bignoniaceae).

The complex orogeny of the Himalaya and the Qinghai-Tibet Plateau (QTP) fosters habitat fragmentation that drives morphological differentiation of mountain plant species. Consequently, determining phylogenetic relationships between plant subgenera using morphological characters is unreliable. Therefore, we used both molecular phylogeny and historical biogeographic analysis to infer the ancestral states of several vegetative and reproductive characters of the montane genus Incarvillea. We determined the taxonomic position of the genus Incarvillea within its family and inferred the biogeographical origin of taxa through Bayesian inference (BI), maximum likelihood (ML) and maximum parsimony (MP) analyses using three molecular data sets (trnL-trnF sequences, nr ITS sequences, and a data set of combined sequences) derived from 81% of the total species of the genus Incarvillea. Within the genus-level phylogenetic framework, we examined the character evolution of 10 key morphological characters, and inferred the ancestral area and biogeographical history of the genus. Our analyses revealed that the genus Incarvillea is monophyletic and originated in Central Asia during mid-Oligocene ca. 29.42 Ma. The earliest diverging lineages were subsequently split into the Western Himalaya and Sino-Himalaya during the early Miocene ca. 21.12 Ma. These lineages resulted in five re-circumscribed subgenera (Amphicome, Olgaea, Niedzwedzkia, Incarvillea, and Pteroscleris). Moreover, character mapping revealed the ancestral character states of the genus Incarvillea (e.g., suffruticose habit, cylindrical capsule shape, subligneous capsule texture, absence of capsule wing, and loculicidal capsule dehiscence) that are retained at the earliest diverging ancestral nodes across the genus. Our phylogenetic tree of the genus Incarvillea differs from previously proposed phylogenies, thereby recommending the placement of the subgenus Niedzwedzkia close to the subgenus Incarvillea and maintaining two main divergent lineages.

Plant endemism in the Nepal Himalayas and phytogeographical implications.

Nepal is located in the central part of the greater Himalayan range with a unique series of mountain chains formed by recent mountain building geological events. As one of the youngest mountains in the world it contributes to diversity of plants and also provided barriers to and corridors through which plants migrated during the ice ages. The higher altitudinal variation with the high mountains, deep river valleys and lowland plains combine with the effects of the summer monsoon and dry winter result with an extraordinary diversity of ecosystems including flora and fauna in a relatively small land area. The existing checklists for Nepal record some 6000 species of flowering plants and about 530 ferns. However, the botanical experts estimate that numbers may go up to 7000 when the poorly known remote regions are fully explored. The information on plant endemism in Nepal Himalaya is not adequately known as Nepal is still struggling to complete long awaited Flora of Nepal project. Endemic species are confined to specific areas and are the first to be affected by land use and other global changes. We sought to explore the spatial distribution of endemic plant species in Nepal in relation to the consequences associated with climatic and geologic changes over time in the region with the help of published literature. It was found that the endemism showed marked spatial variation between open moist habitat and dry inner valleys, the former with higher endemism. The updated records showed 312 flowering plant species to be endemic to Nepal with higher endemism around the elevation of 3800-4200 m at sea level. The recent human population explosion, intensified deforestation, habitat fragmentation and modern day environmental changes are posing greater threats to endemic plant in Nepal. The conservation status and threats to these peculiar species are unknown. Nevertheless, environmental degradation and high poverty rates create a potent mix of threats to biodiversity in this landscape.

Geological and Climatic Factors Affect the Population Genetic Connectivity in Mirabilis himalaica (Nyctaginaceae): Insight From Phylogeography and Dispersal Corridors in the Himalaya-Hengduan Biodiversity Hotspot.

The genetic architecture within a species in the Himalaya-Hengduan Mountains (HHM) region was considered as the consolidated consequence of historical orogenesis and climatic oscillations. The visualization of dispersal corridors as the function of population genetic connectivity became crucial to elucidate the spatiotemporal dynamics of organisms. However, geodiversity and physical barriers created by paleo geo-climatic events acted vigorously to impact notable alterations in the phylogeographic pattern and dispersal corridors. Therefore, to achieve detailed phylogeography, locate dispersal corridors and estimate genetic connectivity, we integrated phylogeography with species distribution modelling and least cost path of Mirabilis himalaica (Edgew.) Heimerl in the HHM. We amplified four cpDNA regions (petL-psbE, rps16-trnK, rps16 intron, trnS-trnG), and a low copy nuclear gene (G3pdh) from 241 individuals of 29 populations. SAMOVA, genealogical relationships, and phylogenetic analysis revealed four spatially structured phylogroups for M. himalaica with the onset of diversification in late Pliocene (c. 3.64 Ma). No recent demographic growth was supported by results of neutrality tests, mismatch distribution analysis and Bayesian skyline plot. Paleo-distribution modelling revealed the range dynamics of M. himalaica to be highly sensitive to geo-climatic change with limited long-distance dispersal ability and potential evolutionary adaptation. Furthermore, river drainage systems, valleys and mountain gorges were identified as the corridors for population genetic connectivity among the populations. It is concluded that recent intense mountain uplift and subsequent climatic alterations including monsoonal changes since Pliocene or early Pleistocene formulated fragmented habitats and diverse ecology that governed the habitat connectivity, evolutionary and demographic history of M. himalaica. The integrative genetic and geospatial method would bring new implications for the evolutionary process and conservation priority of HHM endemic species.

Determining bioclimatic space of Himalayan alder for agroforestry systems in Nepal.

Himalayan alder species are proven to be very useful in traditional as well as contemporary agroforestry practice. These nitrogen-fixing trees are also useful in the land restoration. Therefore, understanding the distribution of Himalayan alder and the potential zone for plantation is meaningful in the agroforestry sector. Suitable climatic zones of Alnus spp. were modelled in MaxEnt software using a subset of least correlated bioclimatic variables for current conditions (1950-2000), topographic variables (DEM derived) and Landuse Landcover (LULC) data. We generated several models and selected the best model against random models using ANOVA and t-test. The environmental variables that best explained the current distribution of the species were identified and used to project into the future. For future projections, ensemble scenarios of climate change projection derived from the results of 19 Earth System Models (ESM) were used. Our model revealed that the most favorable conditions for Alnus nepalensis are in central Nepal in the moist north-west facing slope, whereas for Alnus nitida they are in western Nepal. The major climatic factor that contributes to Alnus species distribution in Nepal appears to be precipitation during the warmest quarter for A. nepalensis and precipitation during the driest quarter for A. nitida. Future projections revealed changes in the probability distribution of these species, as well as where they need conservation and where they can be planted. Also, our model predicts that the distribution of Alnus spp. in hilly regions will remain unchanged, and therefore may represent sites that can be used to revitalize traditional agroforestry systems and extract source material for land restoration.

An ethnobotanical analysis of parasitic plants (Parijibi) in the Nepal Himalaya.

BACKGROUND: Indigenous biocultural knowledge is a vital part of Nepalese environmental management strategies; however, much of it may soon be lost given Nepal's rapidly changing socio-ecological climate. This is particularly true for knowledge surrounding parasitic and mycoheterotrophic plant species, which are well represented throughout the Central-Eastern Himalayas but lack a collated record. Our study addresses this disparity by analyzing parasitic and mycoheterotrophic plant species diversity in Nepal as well as the ethnobotanical knowledge that surrounds them. METHODS: Botanical texts, online databases, and herbarium records were reviewed to create an authoritative compendium of parasitic and mycoheterotrophic plant species native or naturalized to the Nepal Central-Eastern Himalaya. Semi-structured interviews were then conducted with 141 informants to better understand the biocultural context of these species, emphasizing ethnobotanical uses, in 12 districts of Central-Eastern Nepal. RESULTS: Nepal is a hotspot of botanical diversity, housing 15 families and 29 genera of plants that exhibit parasitic or mycoheterotrophic habit. Over 150 of the known 4500 parasitic plant species (~3 %) and 28 of the 160 mycoheterotrophic species (~18 %) are native or naturalized to Nepal; 13 of our surveyed parasitic species are endemic. Of all species documented, approximately 17 % of parasitic and 7 % of mycoheterotrophic plants have ethnobotanical uses as medicine (41 %), fodder (23 %), food (17 %), ritual objects (11 %), or material (8 %). CONCLUSIONS: Parasitic and mycoheterotrophic plant species exhibit high diversity in the Nepal Central-Eastern Himalaya and are the fodder for biocultural relationships that may help inform future environmental management projects in the region.