A new species of Astragalus L. (Leguminosae) from India based on morphological and molecular markers

A new species, Astragalus himachalensis , is described and illustrated from the Himalaya in India. The species grows occasionally in different parts of the cold desert of Lahul-Spiti (Himachal Pradesh). It resembles A. himalayanus , but differs chiefly in the small size of the plants (length, 5–15 cm), diadelphous stamens, and small pods (length, 5–6 mm) with the stipe length (2–3 mm) more or less equal to the calyx length. The similarities and significant differences between A. himachalensis and A. himalayanus were confirmed by analyses of random amplification of polymorphic DNA (RAPD) and directed amplification of minisatellite DNA (DAMD) markers. RAPD and DAMD methods clearly distinguished between the two species and were in congruence with morphological markers. © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 154 , 27–34.     

Increase in light interception cost and metabolic mass component of leaves are coupled for efficient resource use in the high altitude vegetation

Global syntheses of leaf trait scaling relationships report an increase in light interception costs or ‘diminishing returns’ with increase in leaf area. However, variation in light interception costs across ecological gradients and plant strategies to cope up with these costs are not adequately understood. We analyzed leaf area (A) – leaf dry mass (M), leaf water mass (W) – M and W – A scaling relationships in plants occurring in a high altitude region of western Himalaya across environmental gradients to understand changes in light interception cost and metabolic mass component. M represents light interception cost, whereas, W is considered as a proxy of metabolic mass component for liquid phase being the ultimate source of metabolic activity. Trait values were measured from 9278 leaves belonging to 136 dominant species occurring at different sites, slope aspects, elevations and habitat types. Overall, light interception cost increased with increasing A (scaling exponent (α) < 1 in A–M relationship) and metabolic mass component increased disproportionately high with increasing M and A. We found significant differences in scaling exponents of leaf trait relationship between sites, elevations, slope aspects and habitat types, indicating that increase in light interception cost was more evident at higher elevations, southern slopes and open habitats. Further, with increase in light interception cost, metabolic mass component also increased (α > 1 in W–M and W–A relationships). The changes in scaling exponents of various leaf trait relationships across ecological gradients indicated that vegetation of different regions have differences in light interception cost and metabolic mass component. Moreover, increasing light interception cost (increase in mechanical and hydraulic tissues) with increasing A and increasing metabolic mass (leaf thickness) with increasing A and M are favored in high altitude vegetation. This could be a key strategy of high altitude plants for efficient resource capture and use in harsh environments.     

Disentangling evolutionary,environmental and morphological drivers of plant anatomical adaptations to drought and cold in Himalayan graminoids

Understanding what determine plants ability to survive drought and cold is crucial for predicting how plants may respond to ongoing climate change. Plant survival strategies are usually characterized by morphological and physiological adaptations, while their underlying anatomical settings are largely unknown. Woody angiosperms and herbaceous dicots have repeatedly evolved small water transporting conduits and large storage parenchyma tissues at colder or drier places to cope with freezing‐ and drought‐induced damages. However, whether these adaptations are also valid for graminoids remains unclear. Here we show that stem anatomical variations in grasses, sedges and rushes dominating in western Himalayan grasslands are driven by elevation and soil moisture via control over aboveground plant stature and belowground clonal growth, while phylogenetic constraints have only a weak effect. Phylogenetic comparative analyses controlling for confounding factors showed that the elevation‐related cooling controls the conductive system through reduced vessel diameter and extended assimilatory and storage tissues with more chlorenchyma and less sclerenchyma around vessels. The soil moisture deficit, on the other hand, determines stabilization structures by promoting short‐rhizomatous turf graminoids with hollow stems, thicker epidermis and deep adventitious roots in dry steppes and semi‐deserts. Saline wetlands and moist alpine pastures promote long‐rhizomatous short‐stature plants with lower need for mechanical support (absence of hollow stem) and exposure to high evaporative forcing (thinner epidermis). Observed trends of decreasing vessel sizes and lignification rate with elevation supports the existing knowledge that narrower vessels and extensive parenchyma assist plants to grow in cold environments by avoiding freezing‐induced cavitation. Our results bring novel information on ecological drivers influencing the evolution of anatomical adaptations in high mountain graminoids. Distinct grassland types, covering elevations from 2650 to 6150 m, harbor unrelated species with different evolutionary histories that have converged towards similar anatomical structures.     

Occurrence of Phoma Sacc. in the phyllosphere of Neogene Siwalik forest of Arunachal sub-Himalaya and its palaeoecological implications

The present study reports in situ occurrence of two new epiphyllous fungal species of Phomites (comparable to modern genus Phoma Sacc.) on angiospermic leaf remains recovered from the Siwalik sediments (middle Miocene to early Pleistocene) of Arunachal Pradesh, eastern Himalaya. We describe two new species i.e. Phomites siwalicus Vishnu, Khan et Bera S, sp. nov. and Phomites neogenicus Vishnu, Khan et Bera S, sp. nov. on the basis of structural details of pycnidia. The pycnidium is a globose or slightly lens-shaped, ostiolate with a collar layer consisting of thick walled cells, sunken in leaf cuticle, with one-celled conidiospores and short-ampulliform conidiogenous cells. Host leaves resemble to those of extant Dipterocarpus C. F. Gaertn., Shorea Roxb. ex C. F. Gaertn. (Dipterocarpaceae), Dysoxylum Blume (Meliaceae), and Poaceae Barnhart. In situ occurrence of two Phomites morphotypes on the said leaf remains suggests a possible host–parasite interaction in the moist evergreen forest of Arunachal sub-Himalaya during Mio-Pleistocene period. The occurrence of Phomites in appreciable numbers indicates a humid climate favored by high rate of precipitation during Siwalik sedimentation, which is also consistent with our previously published climatic data obtained from the study of the macroscopic plant remains.     

From ‘third pole’ to north pole: a Himalayan origin for the arctic fox

The ‘third pole’ of the world is a fitting metaphor for the Himalayan–Tibetan Plateau, in allusion to its vast frozen terrain, rivalling the Arctic and Antarctic, at high altitude but low latitude. Living Tibetan and arctic mammals share adaptations to freezing temperatures such as long and thick winter fur in arctic muskox and Tibetan yak, and for carnivorans, a more predatory niche. Here, we report, to our knowledge, the first evolutionary link between an Early Pliocene (3.60–5.08 Myr ago) fox, Vulpes qiuzhudingi new species, from the Himalaya (Zanda Basin) and Kunlun Mountain (Kunlun Pass Basin) and the modern arctic fox Vulpes lagopus in the polar region. A highly hypercarnivorous dentition of the new fox bears a striking resemblance to that of V. lagopus and substantially predates the previous oldest records of the arctic fox by 3–4 Myr. The low latitude, high-altitude Tibetan Plateau is separated from the nearest modern arctic fox geographical range by at least 2000 km. The apparent connection between an ancestral high-elevation species and its modern polar descendant is consistent with our ‘Out-of-Tibet’ hypothesis postulating that high-altitude Tibet was a training ground for cold-environment adaptations well before the start of the Ice Age.     

Les principales étapes de l’occupation humaine en bordure de l’Himalaya occidentale

Lithic industries attest that Western Himalayas, Hindu Kush and Pamir as well as the sub-Himalayan belt that is the Siwalik range, were inhabited during the prehistoric times. However, in thin transition zone between plains and high mountains, distinction is to be kept between low-middle altitude regions and high altitude regions (above 2000 m). In the former regions, the first human occupation tenuously appears around 2 Ma. In the Middle Pleistocene, the Lower Palaeolithic industries belong to two technological facies, the Acheulian and the Early Soanian. In the North-Western Siwaliks, the Soanian occurs in plenty on the river terraces, which were all built after 0.4 Ma, and the Acheulian appears between 0.5 and 0.7 Ma. The Middle Palaeolithic is still rich in cobble tools and therefore named Late Soanian. The Upper Palaeolithic is missing, perhaps due to climatic factors and the Neolithic is characterised by polished axes/adzes, but actually many of the cobble tools usually considered as Early Soanian may well belong to the cobble tool technical tradition common in South-East Asia during the Late Pleistocene and Early Holocene. In the north of the mountain range, the entire Palaeolithic sequence yielded by the loess in Southern Tajikistan is characterised, right from the late Lower Pleistocene, by lithic industries mainly compose of flakes, sometimes with cobble tools. In the high altitude zones, prehistoric sites are unknown before the Holocene and therefore they are contemporaneous with the Neolithic but some technological facies display particular features. The question is to know whether the originality of the industries, observed at different periods of time, is linked to techno-cultural adaptations to particular environments or to the isolation of the mountain populations.     

Characterization of midgut trypsin-like enzymes and three trypsinogen cDNAs from the lesser grain borer, Rhyzopertha dominica (Coleoptera: Bostrichidae)

Protein digestion in the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), results from the action of a complex of serine proteinases present in the midgut. In this study we partially characterized trypsin-like enzyme activity against N-alpha-benzoyl-L-arginine p-nitroanilide (BApNA) in midgut preparations and cloned and sequenced three cDNAs for trypsinogen-like proteins. BApNAase activity in R. dominica midgut was significantly reduced by serine proteinase inhibitors and specific inhibitors of trypsin, whereas BApNAase activity was not sensitive to specific inhibitors of chymotrypsin or aspartic proteinases. However, trans-epoxysuccinyl-L-leucylamido-(4-guanidino) butane (E-64) inhibited BApNAase activity by about 30%. BApNAase was most active in a broad pH range from about pH 7 to 9.5. The gut of R. dominica is a tubular tract approximately 2.5 mm in length. BApNAase activity was primarily located in the midgut region with about 1.5-fold more BApNAase activity in the anterior region compared to that in the posterior region. Proteinases with apparent molecular masses of 23-24 kDa that were visualized on casein zymograms following electrophoresis were inhibited by TLCK. Three cDNAs for trypsinogen-like proteins were cloned and sequenced from mRNA of R. dominica midgut. The full cDNA sequences consisted of open reading frames encoding 249, 293, and 255 amino acid residues for RdoT1, RdoT2, and RdoT3, respectively. cDNAs RdoT1, RdoT2, and RdoT3 shared 77-81% sequence identity. The three encoded trypsinogens shared 54-62% identity in their amino acid sequences and had 16-18 residues of signal peptides and 12-15 residues of activation peptides. The three predicted mature trypsin-like enzymes had molecular masses of 23.1, 28, and 23.8 kDa for RdoT1, RdoT2, and RdoT3, respectively. Typical features of these trypsin-like enzymes included the conserved N-terminal residues IVGG62-65, the catalytic amino acid triad of serine proteinase active sites (His109, Asp156, Ser257), three pairs of conserved cysteine residues for disulfide bridges, and the three residues (Asp251, Gly274, Gly284) that determine specificity in trypsin-like enzymes. In addition, RdoT2 has both a PEST-like sequence at the C-terminus and a free Cys158 near the active site, suggesting instability of this enzyme and/or sensitivity to thiol reagents. The sequences have been deposited in GenBank database (accession numbers AF130840 for RdoT1, AF130841 for RdoT2, and AF130842 for RdoT3).     

西域青荚叶实生苗驯化的初步研究

通过对西域青荚叶实生苗驯化方面的实验,得出其驯化成活是各种环境因子综合作用的结果,与原生环境相似的适当的光照(弱、中光)、湿度(高、中湿度)、土壤肥力(高、中肥力)有助于驯化成活.     

Adaptive radiation in Lesser Antillean lizards: molecular phylogenetics and species recognition in the Lesser Antillean dwarf gecko complex, Sphaerodactylus fantasticus

The time associated with speciation varies dramatically among lower vertebrates. The nature and timing of divergence is investigated in the fantastic dwarf gecko Sphaerodactylus fantasticus complex, a nominal species that occurs on the central Lesser Antillean island of Guadeloupe and adjacent islands and islets. This is compared to the divergence in the sympatric anole clade from the Anolis bimaculatus group. A molecular phylogenetic analysis of numerous gecko populations from across these islands, based on three mitochondrial DNA genes, reveals several monophyletic groups occupying distinct geographical areas, these being Les Saintes, western Basse Terre plus Dominica, eastern Basse Terre, Grand Terre, and the northern and eastern islands (Montserrat, Marie Galante, Petite Terre, Desirade). Although part of the same nominal species, the molecular divergence within this species complex is extraordinarily high (27% patristic distance between the most divergent lineages) and is compatible with this group occupying the region long before the origin of the younger island arc. Tests show that several quantitative morphological traits are correlated with the phylogeny, but in general the lineages are not uniquely defined by these traits. The dwarf geckos show notably less nominal species-level adaptive radiation than that found in the sympatric southern clade of Anolis bimculatus , although both appear to have occupied the region for a broadly similar period of time. Nevertheless, the dwarf gecko populations on Les Saintes islets are the most morphologically distinct and are recognized as a full species ( Sphaerodactylus phyzacinus ), as are anoles on Les Saintes ( Anolis terraealtae ).