Quantification of the pattern and spatial distribution of soil organic carbon (SOC) is essential to comprehending many eco-hydrological processes. To obtain a better understanding of the spatial variability of SOC in a typical farming-pastoral zone, 270 soil samples were collected at 45 sampling sites from every 20 cm soil layer. Semi-variance function theory and ordinary Kriging interpolation were applied to identify the spatial variability of SOC. The results showed that SOC in the area was relatively low and decreased with depth and from the basin edge to the centre with a measured mean content of 0.07–0.65 g/kg. The strongest variability in the zone in the top soil layer (0–40 cm) was in the centre part of the zone, which was supposed to be the most concentrated area of human activities in the zone. As soil depth increase, the degree of variation of SOC decreased. Gaussian, exponential, and spherical models were suggested to successfully simulate SOC in different soil depth zones. The spatial distribution of SOC showed strong variability in the same soil depth zone, with a nugget to sill ratio of less than 14% and a range of 30–160 km.
DNA barcoding seeks to assemble a standardized reference library for rapid and unambiguous identification of species, and can be used to screen for potentially cryptic species. The 5′ region of cytochrome oxidase subunit I (COI), which is a mitochondrial DNA (mtDNA) gene fragment, has been proposed as a universal marker for this purpose among animals. However, DNA barcoding of reptiles is still supported only by few datasets compared with other groups. We investigated the utilization of COI to discriminate 34 putative species of vipers, representing almost 92% of the recorded species in China. Based on a total of 241 sequences, our results indicated that the average degree of intraspecific variability (0.0198) tends to be one-sixth the average of interspecific divergence (0.0931), but no barcoding gap was detected between them. The threshold method, BLOG analyses and tree-based methods all can identify species with a high success rate. These results consistently suggested the usefulness and reliability of the DNA barcoding approach in Chinese vipers.
Environmental cues play important roles in the regulation of an animal’s physiology and behavior. The purpose of the present study was to test the hypothesis that ambient temperature was a cue to induce adjustments in body mass, energy intake and thermogenic capacity, associated with changes in serum leptin levels in Eothenomys miletus. We found that E. miletus increased resting metabolic rate (RMR) and energy intake and decreased body mass when exposed to cold while it showed a significant increase in body mass after rewarming. The increase in body mass after rewarming was associated with the higher energy intake compared with the control. Uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT) increased in the cold and reversed after rewarming. Serum leptin levels decreased in the cold while increased after rewarming, associated with the opposite changes in energy intake. Further, serum leptin levels were positively correlated with body mass and body fat mass. Together, these data supported our hypothesis that ambient temperature was a cue to induce changes in body mass and metabolism. Serum leptin, as a starvation signal in the cold and satiety signal in rewarming, was involved in the processes of thermogenesis and body mass regulation in E. miletus.
Eleven high polymorphic across-species loci were used to test the usefulness in the individual identification and parentage determination of black muntjac and to detect the genetic variation in a captive population of the animal. Discrimination power for individual locus ranged from 0.845 to 0.949 with the cumulative discrimination power across the eleven loci being up to 1. The combined exclusion probability across the eleven polymorphic loci in the absence and presence of genetic information on the second parent was 0.999 and 1, respectively. These results indicated that the eleven microsatellites would be highly diagnostic in individual identification and parentage testing for the species. The application of these polymorphic loci to evaluate population genetic variation indicated that the genetic diversity of the captive population (5.4 and 0.68 for A and He, respectively; n = 14) was significantly lower than that of the source population (7 and 0.785 for A and He, respectively; n=16). This supported our previous results discovered by mtDNA d-loop, i.e., the genetic diversity of the captive population had obviously declined over less than 20 years due to the paucity of founders. However, difference of observation heterozygosity between the captive and the source populations was not significant. These results indicated that loss of nuclear diversity in the captive population was first evidenced by A but not Ho. In order to retard the potential inbreeding effect, we suggested that some more wild animals should be introduced into the captive population and that a pedigree-based breeding program should be established.
The disease development and some physiobiochemical indices of 3-4-year-old
Pinus thunbergii inoculated with Bursaphelenchus xylophilus were studied.
The results showed that after nematode invasion, the disease expanded from
the base to the upper part of the main stem, there was an interruption of
resin exudation, drying and pith browning occurred sequentially in stem
xylem, then the needles wilted and finally the plant died. The number of
nematodes increased continuously and rapidly, and increased significantly
just after symptoms appeared in pine seedlings. The stem water content
decreased gradually, stem and leaf relative water content in a new season
branch began to decrease not long before symptoms appeared, and the optical
density of organic acid extract from the stem of pine seedlings increased.
It is suggested that stem water content could be used as a disease
indicator, and organic acid would be the most reliable physiobiochemical
index for early diagnosis of the disease.