Conservation Genetics of the Black Rhinoceros (Diceros bicornis), I: Evidence from the Mitochondrial DNA of Three Populations

Abstract: A drastic decline in the number of black rhinoceroses ( Diceros bicornis ), primarily as a result of poaching places this species in imminent danger of extinction. The remaining black rhinos are divided into small, isolated populations that are vulnerable to demographic extinction, disease epidemics, genetic drift and inbreeding. Some conservationists have suggested minimizing these threats by moving as many animals as possible from different isolated populations to a few safe "rhino sanctuaries." To examine the possible long-term genetic consequences of such a strategy, we focused our efforts on determining the level of genetic differences among the remaining black rhino populations by examining restriction fragment length polymorphisms of the rapidly evolving mitochondrial DNA molecule. The 23 black rhinos in our survey, including animals from three geographic regions and two named subspecies, showed very little mitochondrial DNA differentiation. Only 4 out of 18 restriction enzymes revealed any mtDNA polymorphism, and the average estimated percent sequence divergence between the four mtDNA genotypes observed as 0.17%. Mitochondrial DNA divergence between the two named subspecies, D. b. minor and D. b. michaeli , was estimated to be only 0.29%. These results indicate a very close genetic relationship among the black rhinos in our survey. Thus, the mitochondrial DNA data suggest that within national boundaries, the black rhino populations we sampled may be considered single populations for breeding purposes, which might increase the species' probability of survival.     

Clean catalytic technology for liquid phase hydrocarbon oxidation

 Liquid phase hydrocarbon oxidation is one of the principal routes towards industrial organic chemicals. However, low product selectivity and associated by-product formation are major problems in several oxidation processes. As a result of the increasingly stringent environmental regulations, the development of oxidation catalysts has been a major challenge in the last decade. An overview of novel selective and clean oxidation catalysts and processes is presented. Received: 27 July 1998 / Accepted: 8 September 1998     

Structural-temporal organization of a rodent community in the Teletskaya Taiga,Altai Mountains

The structural-temporal organization of a murine rodent community in the taiga has been studied near Lake Teletskoe, Mountain Altai. The results show that the long-term dynamics of indices characterizing community diversity depend mainly on changes in the structure of dominance rather than on the population dynamics of species. The distribution of species in the factor space corresponds to their preference for certain biotopes, from dry to relatively moist. An analysis of relationships within the rodent community has revealed the synchronous dynamics of species abundance and antiphase pattern of changes in the structural indices of dominant species.     

Chemical pollution: Transfer of chemical elements to the aboverground phytomass of herbaceous plants

Changes in the species composition and a decrease in species diversity and total plant biomass along the gradient of soil pollution with heavy metals have been shown. Data on the concentrations of chemical elements (Zn, Cu, Cd, Pb, Co, Ni, Mn, Cr, and Fe) in the aboveground organs of herbaceous plants and the biomass of each species make it possible to estimate the role of higher producers in the incorporation of chemical elements into biogenic cycles in background zones and under conditions of chemical pollution. Plants of the composite family (Asteraceae) play the main role in accumulation of chemical elements. The results obtained indicate that natural ecosystems have mechanisms limiting excessive accumulation of chemical elements into the aboveground plant biomass.     

一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。