Population viability analysis of small population: a case study for Asian elephant in China.

Small populations are at risk of extinction from deterministic and stochastic factors. Less than 250 Asian elephants (Elephas maximus) remain in China, and are distributed in a few isolated areas; yet, population viability analyses of this endangered population have not been conducted. Here, the current genetic status of the Pu'Er-Mengyang Asian elephant populations in China was analyzed, and the risk of extinction was predicted over the next 500 years. Factors affecting the viability of this population were determined through simulations. The genetic diversity of the population was very low (mean allele number: 3.1; expected heterozygosity: 0.463), even though a recent population bottleneck was not detected. The effective population size was approximately 24.1 adult elephants. Enough adult breeding individuals exist to maintain population viability. VORTEX simulation model showed that this population would not go extinct in the next 500 years. However, illegal poaching and harvesting could negatively affect population size. A sensitivity analysis showed that the mean stochastic growth rate of the study population is sensitive to sex ratio, number of breeding females, mortality of females of different age classes, carrying capacity, and lethal equivalents. Based on our results, we suggest that action should be taken to alleviate inbreeding and any further loss of genetic diversity, by connecting fragmented elephant habitat or by translocating individual elephants. In addition, human-elephant conflict should be mitigated using various modern approaches, including crop guarding techniques, and by encouraging farmers to switch to crops and income sources not vulnerable to elephant raids.

Conflict between conservation and development: cash forest encroachment in Asian elephant distributions.

Over the last 4 decades, China has undergone major economic development, resulting in considerable impacts on its wildlife populations and habitats. It is essential to quantify the conflict between development and conservation to assist with policy-making because forestry policies and market trends affected indirectly the distribution of Asian elephants. Here, we mapped the historical distribution of elephants versus human land use. Elephant distributions appear to occur in unbroken natural forests only. However, over the 40-year period, the distribution ranges have become smaller and fragmented, with natural forest area also declining by 16%. The monoculture of cash trees is encroaching on natural forests. Over the past 10 years, rubber plantations have become concentrated in the south, with extensive natural forests and scattered rubber farms being converted to tea plantations, due to changes in governmental policies and product prices. Through mapping the spatial changes in the distribution of rubber and tea plantations, our study is expected to help local managers to incorporate the needs of endangered elephants through creating space when planning plantations, especially in Xishuangbanna and the south part of Pu'er. In conclusion, restoring elephant habitat and establishing ecological corridors are critical for the survival of elephants in this region.

[Post-transplant kidney from C-III donation after cardiac death of children: a clinicopathologic study of 20 cases].

OBJECTIVE: To study the clinical and histopathologic features of post-transplant kidney biopsy tissues from pediatric C-III donors. METHODS: The clinical and pathologic features of 20 cases (22 case-times) of renal transplant biopsies from pediatric cadaveric donors were analyzed by light microscopy and immunohistochemistry according to the Banff system of working classification of renal allograft pathology. Biopsies were compared to those from adult C-III donors and adult cadaveric donors. RESULTS: Sixteen cases (72.7%) showed renal allograft drug toxicity damage by Tacrolimus, seven cases (31.8%) showed degeneration and necrosis of renal tubular epithelial cells, four cases (18.2%) showed T cell-mediated acute rejection and six cases (27.3%) showed renal interstitial inflammation. There were two cases (9.1%) of renal dysplasia and one case (4.5%) of renal infarction. There was insufficient evidence for diagnosis of renal allograft nephropathy. Compared to post-transplant kidney from adult C-III donors, the proportion of drug toxicity damage was higher (P<0.05). Compared to post-transplant kidney from adult cadavers, the proportions of drug toxicity damage, degeneration and necrosis of renal tubular epithelial cells were higher (P<0.05) while the proportion of acute rejection was lower (P<0.05). CONCLUSIONS: The pathologic changes in the post-transplant kidneys from pediatric donors are different from those from adult donors. Optimal long-term outcome can be accomplished by effective treatment based on timely or procedural biopsy.