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A New Species of Gracixalus (Anura: Rhacophoridae) from West Guangxi, China
Get PDFWe discovered a new species of the genus Gracixalus, Gracixalus tianlinensis sp. nov. which is morphologically almost similar to G. jinggangensis, G. jinxiuensis and G. sapaensis, but is distinguished from these species and all other rhacophorids in China and adjoining countries by a combination of the following characters: (1) SVL 30.3-35.9 mm in male, 35.6-38.7 mm in female, (2) head length less than head width, (3) vomerine teeth absent, (4) supratympanic fold distinct, (5) axilla and posterior surface of flanks pale yellow, (6) nuptial pads distinct on Finger I and slightly visible on Finger II, (7) dorsum brown to beige, with an inverse Y-shaped dark brown marking, (8) single subgular vocal sac. Our preliminary phylogenetic analyses implied G. tianlinensis sp. nov. is sister to G. sapaensis with well-supported values. Currently, this new species is known to be distributed in montane evergreen forests in association with montane bamboo in Cenwanglaoshan National Nature Reserve, Tianlin County, Guangxi, China
Amphibian Species Contribute Similarly to Taxonomic, but not Functional and Phylogenetic Diversity: Inferences from Amphibian Biodiversity on Emei Mountain
Get PDFUnderstanding the relationships between species, communities, and biodiversity are important challenges in conservation ecology. Current biodiversity conservation activities usually focus on species that are rare, endemic, distinctive, or at risk of extinction. However, empirical studies of whether such species contribute more to aspects of biodiversity than common species are still relatively rare. The aim of the present study was to assess the contribution of individual amphibian species to different facets of biodiversity, and to test whether species of conservation interest contribute more to taxonomic, functional, and phylogenetic diversity than do species without special conservation status. To answer these questions, 19 000 simulated random communities with a gradient of species richness were created by shuffling the regional pool of species inhabiting Emei Mountain. Differences of diversity values were then computed before and after removing individual species in these random communities. Our results indicated that although individual species contributed similarly to taxonomic diversity, their contribution to functional and phylogenetic diversity was more idiosyncratic. This was primarily driven by the diverse functional attributes of species and the differences in phylogenetic relationships among species. Additionally, species of conservation interest did not show a significantly higher contribution to any facet of biodiversity. Our results support the claims that the usefulness of metrics based only on species richness is limited. Instead, assemblages that include species with functional and phylogenetic diversity should be protected to maintain biodiversity
Effects of Increased Salinity on Growth, Development and Survival in Early Life Stages of the Green Toad Bufotes Variabilis (Anura: Bufonidae)
Get PDFThis study examined the effects of increased salinity on growth, development and survival of the Green toad, Bufotes variabilis during embryonic, hatching and early larval periods. Eggs from a single cohort of B. variabilis were subjected to acute and chronic toxicity tests for water salinity ranging from 0.20 to 10 g of salt per liter. Results obtained from this study showed that salinity over 3.70 g/l increased embryonic mortality and reduced percentage of hatching and survival rate of larvae. As larvae tolerated salinity 0.20 to 3.70 g/l with highest survival, but salinity of 10 g/l caused mortality of all individuals within 12 h, 7.70–8.70 (g/l) within 4.5 days, 5.70–6.70 g/l within 10 days and 4.70 (g/l) were tolerated within 14 days. Salinity less than 0.70 g/l did not affect survival and hatching success of the embryos. After a 3-week experiment, size of larvae exposed to salinities over 0.70 g/l was lower compared to larvae reared at lower salinity levels. Meanwhile increases in salinity more than 3.70 g/l caused extension in the hatching period. Larvae reared at salinity of 3.70 to 4.70 g/l had morphological abnormalities, such as distortion of tail
Modeling the Past and Current Distribution and Habitat Suitability for Ablepharus grayanus and A. pannonicus (Sauria: Scincidae)
Get PDFStudy of the climate variability in the past and present, and correlating those with changes in the distribution range of species has attracted considerable research interest. The genus Ablepharus consists of 10 recognized species, of which A. bivittatus, A. grayanus and A. pannonicus are documented from Iran. In the present study, we modeled with MaxEnt the potential distribution areas and determined the suitable habitats in past (mid-Holocene [MH], and the Last Interglacial [LIG]) and their current distribution for two species of snake-eyed skinks (A. grayanus and A. pannonicus) separately. Models of the species indicated good fit by the average high area under the curve (AUC) values (A. grayanus = 0.929 ± 0.087 and A. pannonicus = 0.979 ± 0.007). Precipitation of the driest quarter of the year, mean temperature of the coldest quarter of the year, and precipitation of the driest month variables made important contributions to A. grayanus. Two important climate variables contributed importantly to A. pannonicus; temperature seasonality, and mean temperature of the wettest quarter of the year, and one topographic variable, slope. We conclude that these variables form a natural barrier for species dispersal. The MH and the LGM models indicated a larger suitable area than the current distribution
Competitive McLafferty-type rearrangements of sodium adduct of anti-2,3-dihydroxy-1-phenylpentane-1,4-dione compounds in tandem mass spectrometry
No full textSodium adducts of anti-2,3-dihydroxy-1-phenylpentane-1,4-dione compounds with different substituents were studied by collision-induced dissociation. McLafferty-type rearrangements preceding fragmentation were found as their main fragmentation pathway. Coordination of sodium cation to the oxygen functions may either lead to formation of a five-membered or a six-membered ring. Two McLafferty-type rearrangement product ions exhibiting a mass difference of 2 u indicated that two competitive McLafferty-type rearrangements through a six-membered ring coordination occurred. Relative abundances of the corresponding product ions were studied by energy-resolved collision-induced dissociation experiments and density functional theory calculations. Furthermore, the influence of different substituents was probed
Evolutionary melting pots and reproductive isolation: A ring-shaped diversification of an odorous frog (Odorrana margaratea) around the Sichuan Basin
No full textQuaternary climatic oscillations and geography are of primary importance in shaping intraspecific genetic diversity. We examined the diversification patterns and inferred processes for the green odorous frog (Odorrana margaretae) of western China. Species distribution modelling showed that the species has a continuous circular distribution around the Sichuan Basin while the basin itself is largely uninhabitable. Population genetic and phylogenetic analyses revealed that the species has a ring-shaped divergent pattern. While the chain of populations around the Basin maintains a mostly gradual and continuous genetic variation, populations between the north and west showed little gene exchange. Two processes, glacial refugial history and geography, likely contributed to the observed patterns. Our genetic clustering analysis revealed two clusters, suggesting two refugial groups among the populations, one from the west and the other from the east. Postglacial expansion may have created two contact zones. One at the south had extensive population admixture and produced a gradual transition between the western and eastern populations. Consequently, this region has the highest genetic diversity and represents an evolutionary "melting pot." In contrast, the second contact zone at the northwestern side of the Basin has limited admixture, suggesting partial reproductive isolation between the northern and western populations. Furthermore, an isolation-by-distance analysis revealed a strong correlation (Mantel r = 0.745) between the genetic and geographic distances, when we assumed that populations were connected following the circular distribution without gene flow across the NW contact zone. We also explored alternative explanations, such as a one-refugium scenario. With its micro-ring, the green odorous frog is poised to make an excellent model system for understanding the process of speciation
Nitrogen addition reduces soil bacterial richness, while phosphorus addition alters community composition in an old-growth N-rich tropical forest in southern China
No full textIncreased nitrogen (N) deposition endangers the biodiversity and stability of forest ecosystems, and much of the original phosphorus (P) parent material continues to decrease in most lowland tropical forests. It remains poorly understood as to how soil microbial diversity at a molecular level responds to the addition of excess N and mitigation of soil P limitation, as well as their influencing factors, in the N-rich tropical forest ecosystems. To reach a better understanding, we conducted a six-year N and P-addition experiment consisting of three treatments: N-addition (150 kg N ha(-1) yr(-1)), P-addition (150 kg P ha(-1) yr(-1)), and NP-addition (150 kg N ha(-1) yr(-1) plus 150 kg P ha(-1) yr(-1)), besides a control treatment in an old-growth tropical forest in southern China. We examined the snapshot responses of soil bacterial richness and community composition to the elevated N and P levels after six years using a 16S rRNA gene MiSeq sequencing method. The soil bacterial alpha-diversity, which is represented by Chao1 index in terms of bacterial richness, was 783 +/- 87 (mean +/- SD) across all samples in this study. The N addition caused a decline in soil bacterial richness, most likely through its negative effect on soil pH. The decrease in soil pH resulted from the direct N input and indirect NO3- increase. However, the P treatment had no effect on soil bacterial richness. The NP treatment also reduced the soil bacterial richness as the N addition. These results suggested that the P input could not alleviate the loss of soil bacterial richness induced by excess N deposition in the old-growth N-rich tropical forest. The Acidobacteria, which comprised 31.1% of the soil bacterial community, were the most dominant bacteria across all samples. The addition of P shifted the soil bacterial community composition. The elevated P availability with P-addition and the decreased understory plant coverage in the N-input treatment altered the soil bacterial beta-diversity. Our results highlight the different roles of N and P depositions in shaping the soil bacterial richness and community composition, thereby causing concomitant changes in understory plant and underground microbial communities in this ecosystem
Skin innate immunity of diskless-fingered odorous frogs (Odorrana grahami) with spatial-temporal variations
No full textThe skin innate immunities of diskless-fingered odorous frogs (Odorrana grahami) from three populations were investigated. The antimicrobial capacities of skin secretions against the 60 representative environmental bacterial strains were evaluated using the values of the minimum inhibitory concentration (MIC) equivalents, which were defined as the volumes of antimicrobial solution just inhibiting the tested bacteria per 1 cm(2) of surface area, from 0.06 to 9.10 mL/cm(2). Our results revealed significantly different skin antimicrobial capacities among the three populations: Mianning < Huili < Kunming. Within the frog population, the skin antimicrobial capacities are highly variable depending on the season: in Mianning frogs, summer < autumn and spring; in Huili frogs, spring < autumn < summer; in Kunming frogs, autumn < spring < summer. The animal density and body mass significantly impacted the skin antimicrobial capacity, while the sex ratio and soil or water bacterial counts did not
Linking leaf hydraulic properties, photosynthetic rates, and leaf lifespan in xerophytic species: a test of global hypotheses
No full textPremise of the Study Methods Leaf venation and its hierarchal traits are crucial to the hydraulic and mechanical properties of leaves, reflecting plant life-history strategies. However, there is an extremely limited understanding of how variation in leaf hydraulics affects the leaf economic spectrum (LES) or whether venation correlates more strongly with hydraulic conductance or biomechanical support among hierarchal orders. We examined correlations of leaf hydraulics, indicated by vein density, conduit diameter, and stomatal density with light-saturated photosynthetic rates, leaf lifespan (LLS), and leaf morpho-anatomical traits of 39 xerophytic species grown in a common garden. Key Results Conclusions We found positive relationships between light-saturated, area-based photosynthetic rates, and vein densities, regardless of vein orders. Densities of leaf veins had positive correlations with stomatal density. We also found positive relationships between LLS and vein densities. Leaf area was negatively correlated with the density of major veins but not with minor veins. Most anatomical traits were not related to vein densities. We developed a network diagram of the correlations among leaf hydraulics and leaf economics, which suggests functional trade-offs between hydraulic costs and lifetime carbon gain. Leaf hydraulics efficiency and carbon assimilation were coupled across species. Vein construction costs directly coordinated with the LLS. Our findings indicate that hierarchal orders of leaf veins did not differ in the strength of their correlations between hydraulic conductance and biomechanical support. These findings clarify how leaf hydraulics contributes to the LES and provide new insight into life-history strategies of these xerophytic species
