Multiple maternal origins of chickens: Out of the Asian jungles

Domestic chickens have long been important to human societies for food, religion, entertainment, and decorative uses, yet the origins and phylogeography of chickens through Eurasia remain uncertain. Here, we assessed their origins and phylogeographic hist

More evidence for non-maternal inheritance of mitochondrial DNA?

Background: A single case of paternal co-transmission ofmitochondrial DNA (mtDNA) in humans has been reported so far. Objective: To find potential instances of non-maternal inheritance of mtDNA. Methods: Published medical case studies (of single patients) were searched for irregular mtDNA patterns by comparing the given haplotype information for different clones or tissues with the worldwide mtDNA database as known to date-a method that has proved robust and reliable for the detection of flawed mtDNA sequence data. Results: More than 20 studies were found reporting clear cut instances with mtDNAs of different ancestries in single individuals. As examples, cases are reviewed from recent published reports which, at face value, may be taken as evidence for paternal inheritance of mtDNA or recombination. Conclusions: Multiple types (or recombinant types) of quite dissimilar mitochondrial DNA from different parts of the known mtDNA phylogeny are often reported in single individuals. From re-analyses and corrigenda of forensic mtDNA data, it is apparent that the phenomenon of mixed or mosaic mtDNA can be ascribed solely to contamination and sample mix up.

Molecular characterization of common carp (Cyprinus carpio) Sonic Hedgehog and discovery of its maternal expression

Sonic hedgehog (Shh), one of important homologous members of the hedgehog (Hh) family in vertebrates, encodes a signaling molecule that is involved in short- or long-range patterning processes during embryogenesis. In zebrafish, maternal activity of Hh was found to be contributing to the formation of primary motoneurons. However, we found that all of the known Hh members were not maternally expressed in zebrafish. In the present study, full-length cDNA of common carp (Cyprinus carpio) Shh (cShh) was gained by degenerate reverse-transcription PCR (RT-PCR) and rapid amplification of cDNA ends. Sequence comparison shows that cShh coding sequence shares 93.4% identity with zebrafish Shh coding sequence, and their corresponding protein sequences have 91.9% similarity. Comparative analysis of Shh genomic sequences and Hh protein sequences from different species revealed that the genomic structures of Hh are conserved from invertebrate to vertebrate. In contrast to zebrafish Shh, cShh transcripts were detectable from one-cell stage by RT-PCR analysis. Whole mount in situ hybridization verified the maternal expression of Shh in common carp, which is, to our knowledge, the first report of that in vertebrates, suggesting that Shh might be responsible for the maternal Hh activity in common carp.

A data-model fusion approach for upscaling gross ecosystem productivity to the landscape scale based on remote sensing and flux footprint modelling

Chinese Academy of Sciences ; National Science Foundation of China [41071059]; National Key Technology R&D Program of China [2008BAK50B06-02]; National Basic Research Program of China [2010CB950900, 2010CB950704]; Natural Sciences and Engineering Research Council of Canada

Assessing the consequence of land use change on agricultural productivity in China

China's cultivated land has been undergoing dramatic changes along with its rapidly growing economy and population. The impacts of land use transformation on food production at the national scale, however, have been poorly understood due to the lack of detailed spatially explicit agricultural productivity information on cropland change and crop productivity. This study evaluates the effect of the cropland transformation on agricultural productivity by combining the land use data of China for the period of 1990-2000 from TM images and a satellite-based NPP (net primary production) model driven with NOAH/AVHRR data. The cropland area of China has a net increase of 2.79 Mha in the study period, which causes a slightly increased agricultural productivity (6.96 Mt C) at the national level. Although the newly cultivated lands compensated for the loss from urban expansion, but the contribution to production is insignificant because of the low productivity. The decrease in crop production resulting from urban expansion is about twice of that from abandonment of arable lands to forests and grasslands. The productivity of arable lands occupied by urban expansion was 80% higher than that of the newly cultivated lands in the regions with unfavorable natural conditions. Significance of cropland transformation impacts is spatially diverse with the differences in land use change intensity and land productivity across China. The increase in arable land area and yet decline in land quality may reduce the production potential and sustainability of China's agro-ecosystems. (C) 2008 Elsevier B.V. All rights reserved.

Impacts of LUCC processes on potential land productivity in China in the 1990s

Using meteorological data and RS dynamic land-use observation data set, the potential land productivity that is limited by solar radiation and temperature is estimated and the impacts of recent LUCC processes on it are analyzed in this paper. The results show that the influence of LUCC processes on potential land productivity change has extensive and unbalanced characteristics. It generally reduces the productivity in South China and increases it in North China, and the overall effect is increasing the total productivity by 26.22 million tons. The farmland reclamation and original farmlands losses are the primary causes that led potential land productivity to change. The reclamation mostly distributed in arable-pasture and arable-forest transitional zones and oasises in northwestern China has made total productivity increase by 83.35 million tons, accounting for 3.50% of the overall output. The losses of original farmlands driven by built-up areas invading and occupying arable land are mostly distributed in the regions which have rapid economic development, e.g. Huang-Huai-Hai plain, Yangtze River delta, Zhujiang delta, central part of Gansu, southeast coastal region, southeast of Sichuan Basin and Urumqi-Shihezi. It has led the total productivity to decrease 57.13 million tons, which is 2.40% of the overall output.

EFFECT OF DENSITY ON LARVAL DEVELOPMENT AND FEMALE PRODUCTIVITY OF TISBE-HOLOTHURIAE (COPEPODA, HARPACTICOIDA) UNDER LABORATORY CONDITIONS

POPULATION-DYNAMICS; FOOD; FISH

Effect of plateau zokors on vegetation characteristics and productivity of alpine meadow

This research was conducted on alpine meadow site at Menyuan county, Qinghai Province, People's Republic of China to determine the effects of native, subterranean rodent of Qinghai-Tibet grasslands, the plateau zokors (Myospalax baileyi), on seasonal above-and below-ground plant biomass, plant species diversity and productivity. Both total peaks of above-and below-ground biomass were the greatest (413.600 g/m~2 and 2297.502 g/m~2) in the patch no any plateau zokors colonized by plateau zokors over 10 years in August and October, respectively. Both above-and below-ground biomass were significantly increased in the patches where plateau zokors were removed or the burrow systems were abandoned for five years compared to the patches plateau zokors colonized over 10 years. However, both above-and below-ground biomass in abandoned patches were significantly lower than that in uncolonized patches. Monocotyledonous biomass was reduced greatly, but the non-palatable dicots were significantly increased in colonized patches. The palatable biomass of monocots and dicots were increased in abandoned patches. Total plant species diversity was the greatest in uncolonized patchesand least in abandoned patch. The total net primary production in colonized patches was reduced by 68.98% compared with uncolonized patches. Although the patches were without any plateau zokors disturbance for fives years, the total net primary production just reached 58.69% of the uncolonized patches. The above-ground net primary production in abandoned patches increased 28.74% and the below-ground increased 54.91% compared with the colonized patches. We suggest that plateau zokor-induced changes in plant above- and below-ground biomass and species diversity may lead to further alterations of nutrient cycling and trophic dynamics in this alpine meadow ecosystem.

Molecular evidence for double maternal origins of the diploid hybrid Hippophae goniocarpa (Elaeagnaceae)

Homoploid hybrid plant species are rare, and the mechanisms of their speciation are largely unknown, especially for homoploid hybrid tree species. Two contrasting hypotheses have been proposed to explain the origin of Hippophae goniocarpa: (1) it is a diploid hybrid originating from H. rhamnoides ssp. sinensis x H. neurocarpa ssp. neurocarpa, and (2) it originated via marginal differentiation from H. rhamnoides ssp. sinensis. Regardless of which of these hypotheses is true (if either), previous studies have suggested that H. rhamnoides ssp. sinensis is the only maternal donor for this hybrid species. In this study, we aim to elucidate the maternal composition of H. goniocarpa and to test the two hypotheses. For this purpose, we sequenced the maternal chloroplast DNA trnL-F region of 75 individuals representing H. goniocarpa, H. rhamnoides ssp. sinensis, and H. neurocarpa ssp. neurocarpa in two co-occurring sites of the taxa. Seven haplotypes were identified from three taxonomic units, and their phylogenetic relationships were further constructed by means of maximum parsimony, maximum likelihood, and network analyses. These seven haplotypes clustered into two distinct, highly divergent lineages. Two haplotypes from one lineage were found in H. rhamnoides ssp. sinensis, and five (representing the other lineage) in H. neurocarpa ssp. neurocarpa. Hippophae goniocarpa shared four common haplotypes from both lineages, but the haplotypes detected from the two populations differed to some extent, and in each case were identical to local haplotypes of the putative parental species. Thus, both H. rhamnoides ssp. sinensis and H. neurocarpa ssp. neurocarpa appear to have together contributed to the maternal establishment of H. goniocarpa. These results clearly demonstrate that the marginal origin hypothesis should be rejected, and support the hybrid origin hypothesis. Hippophae goniocarpa exhibits a sympatric distribution with its two parent species, without occupying new niches or displaying complete ecological isolation. However, this species has effectively developed reproductive isolation from its sympatric parent species. Our preliminary results suggest that H. goniocarpa may provide a useful model system for studying diploid hybrid speciation in trees. (c) 2008 The Linnean Society of London.

Net primary productivity and spatial distribution of vegetation in an alpine wetland, Qinghai-Tibetan Plateau

To initially describe vegetation structure and spatial variation in plant biomass in a typical alpine wetland of the Qinghai-Tibetan Plateau, net primary productivity and vegetation in relationship to environmental factors were investigated. In 2002, the wetland remained flooded to an average water depth of 25 cm during the growing season, from July to mid-September. We mapped the floodline and vegetation distribution using GPS (global positioning system). Coverage of vegetation in the wetland was 100%, and the vegetation was zonally distributed along a water depth gradient, with three emergent plant zones (Hippuris vulgaris-dominated zone, Scirpus distigmaticus-dominated zone, and Carex allivescers-dominated zone) and one submerged plant zone (Potamogeton pectinatus-dominated zone). Both aboveground and belowground biomass varied temporally within and among the vegetation zones. Further, net primary productivity (NPP) as estimated by peak biomass also differed among the vegetation zones; aboveground NPP was highest in the Carex-dominated zone with shallowest water and lowest in the Potamogeton zone with deepest water. The area occupied by each zone was 73.5% for P. pectinatus, 2.6% for H. vulgaris, 20.5% for S. distigmaticus, and 3.4% for C. allivescers. Morphological features in relationship to gas-transport efficiency of the aerial part differed among the emergent plants. Of the three emergent plants, H. vulgaris, which dominated in the deeper water, showed greater morphological adaptability to deep water than the other two emergent plants.

Effects of altitude on plant-species diversity and productivity in an alpine meadow, Qinghai-Tibetan plateau

During the growing seasons of 2002 and 2003, biomass productivity and diversity were examined along an altitudinal transect on the south-western slope of Beishan Mountain, Maqin County (33 degrees 43'-35 degrees 16'N, 98 degrees 48'-100 degrees 55'E), Qinghai-Tibetan Plateau. Six altitudes were selected, between 3840 and 4435 m. Soil organic matter, soil available N and P and environmental factors significantly affected plant-species diversity and productivity of the alpine meadows. Aboveground biomass declined significantly with increasing altitude (P < 0.05) and it was positively and linearly related to late summer soil-surface temperature. Belowground biomass (0 - 10-cm depth) was significantly greater at the lowest and highest altitudes than at intermediate locations, associated with water and nutrient availabilities. At each site, the maximum belowground biomass values occurred at the beginning and the end of the growing seasons (P < 0.05). Soil organic matter content, and available N and P were negatively and closely related to plant diversity (species richness, Shannon-Wiener diversity index, and Pielou evenness index).

The effect of land management on plant community composition, species diversity, and productivity of alpine Kobersia steppe meadow

Grassland degradation is widespread and severe on the Tibet Plateau. To explore management approaches for sustainable development of degraded and restored ecosystems, we studied the effect of land degradation on species composition, species diversity, and vegetation productivity, and examined the relative influence of various rehabilitation practices (two seeding treatments and a non-seeded natural recovery treatment) on community structure and vegetation productivity in early secondary succession. The results showed: (1) All sedge and grass species of the natural steppe meadow had disappeared from the severely degraded land. The above-ground and root biomass of severely degraded land were only 38 and 14.7%, respectively, of those of the control. So, the original ecosystem has been dramatically altered by land degradation on alpine steppe meadow. (2) Seeding measures may promote above-ground biomass, particularly grass biomass, and ground cover. Except for the grasses seeded, however, other grass and sedge species did not occur after seeding treatments in the sixth year of seeding. Establishment of grasses during natural recovery treatment progressed slowly compared with during seeding treatments. Many annual forbs invaded and established during the 6 years of natural recovery. In addition, there was greater diversity after natural recovery treatment than after seeding treatments. (3) The above-ground biomass after seeding treatment and natural recovery treatment were 114 and 55%, respectively, of that of the control. No significant differences in root biomass occurred among the natural recovery and seeded treatments. Root biomass after rehabilitation treatment was 23-31% that of the control.