Beta diversity is an important component of biological diversity, measuring compositional change in species assemblages across temporal and spatial scales. Beta diversity concerns not only a number of ecological and evolutionary issues, but can also guide the selection of protected areas and help to optimize conservation networks. It has thus become a hot topic in biodiversity research in recent years. Researchers have used various measures and analytical methods to investigate patterns of beta diversity and its underlying mechanisms for various taxa and in different regions. Here, we reviewed literature from the past decade pertaining to the following aspects of beta diversity: metrics, temporal and spatial patterns, determinants and applications in biodiversity conservation. Whittaker introduced the term beta diversity in 1960, but defined it vaguely. As the concept of beta diversity evolved, a high variety of measures were developed to quantify the concept. The comparison of results from different studies may be hindered by the variety of measures used to quantify beta diversity. Presently, the most popular methods for measuring beta diversity are similarity/dissimilarity coefficients such as Jaccard index and Sørensen index. In the last few years, several methods to quantify beta diversity have emerged, some of which are worth noting. Beta diversity depends on temporal scale, spatial scale and taxonomic scale, and decreases with increasing analytical grain size. There is no consensus among scientists that beta diversity decreases with latitude, i.e. that it is higher in tropics and lower near the poles. Beta diversity is high within mountain ranges and at the interface of biogeographic realms; thus, larger/more reserves are needed in these regions to cover the entire gradient of species turnover. Studies on beta diversity across temporal scales have shown that climatic change has resulted in shifts in species composition through time, and that the migration of species between different continents/regions has led to biotic homogenization. Based on a thorough review of beta diversity literature, we think the following questions might be the focus of future research: (1) the influence of evolutionary history and biological characteristics of different taxonomic groups on their beta diversity; (2) the influence of temporal/spatial scales on beta diversity and its determinants; and (3) the effect of anthropogenic activities on beta diversity.

More concerns have been focused on transgenic trees than transgenic food crops because of their longevity and the likelihood that transgene might spread to related species of wild trees grown nearby. Detailed, the long life span of trees could increase the likelihood of transgene instability, affect diversity of non-target organisms, improve resistance to insecticidal proteins, increase invasiveness of the tree itself (weediness), and arouse negative environmental consequences or new environmental risks resulted from gene flow or gene escape. The transgenic black poplar Populus nigra carrying Bt gene and hybrid white poplar clone 741[Populus alba× (P. davidiana + P. simonii) × P. tomentosa] carring fusion genes, which are resistant to leaf insects, have been commercial release in China since 2002. In this review, we provide a brief overview of biosafety assessment researches on transgenic insect-resistant poplar varieties during the last decades. Arthropod population and community structure have changed within the transgenic poplar plantations, and the diversity of the insect community has increased. But there are no significant changes for soil microbial communities. Gene flow monitoring in the transgenic black poplar plantation showed that the probability of gene escape is very low via pollen and seeds. The potential environment risk was also evaluated based on the experiments of horizontal gene transfer from transgenic poplars through endophytic bacteria. We pointed out the necessity of the biosafety assessments concerning the transgenic poplars when intercropping with food crops.

Ephemerals, including annual ephemerals and ephemeroid plants, are characterized by short-term growth rhythms and specific biological traits adapted to deserts or temperate broad-leaved deciduous forests. Few studies have been carried out on ephemeral community composition and their relationships with temperature and precipitation regimes in the desert. Between 2005 and 2008, we monitored early-spring ephemeral communities in 201 quadrats along 25 line transects in the Mosuowan area of the Dzungaria Desert, northern Xinjiang where ephemerals represent a special desert floral group. We also collected temperature and precipitation data to analyze the effects of these factors on ephemeral adaptation. We found that ephemerals dominated the plant community in early spring, accounting for 52% of species observed. Six of seven species with a frequency over 40% were ephemerals, they were Eremopyrum orientale,Malcolmia scorpioides,Arnebia decumbens, Lappula semiglabra, Tetracme quadricornis andAtriplex dimorphostegia. Abundance of ephemerals has closely negatively relationship with the winter temperature in the previous year, suggesting that low temperature in the previous winter facilitates sprouting of ephemerals in the current year. However, community structure depended more on temperature and precipitation in early spring in the current year than the previous year. Annual changes in Shannon-Wiener and Pielou indices of these communities were consistent with annual changes in total amount of spring and winter precipitation. Therefore, variation in temperature and precipitation regimes is likely the main factor involved with inter-year changes in the structure of ephemeral plant communities in the Dzungaria Desert, Xinjiang.

To explore the spatio-temporal distributional patterns of the vegetation in a Karst cluster-peak-depression region, we investigated the species composition and diversity characteristics of three forests inside 200 m × 40 m dynamic monitoring plots in Huanjiang County of Guangxi. Results showed that plant communities changed from plantation to secondary forest to primary forest with increasing diversity associated with reduced disturbance intensity. We recorded 65 woody species belonging to 26 families and 52 genera, 100 woody species belonging to 33 families and 68 genera, and 123 woody species belonging to 43 families and 91 genera in the plantation, secondary, and primary forests, respectively. Evergreens accounted for 41.5%, 47.0%, and 52.9% of species in the plantation, secondary, and primary forests, respectively. Meanwhile, the families characterized with one species accounted for 39.46%, 36.36%, and 53.66% of the total families in the plantation, secondary, and primary forests, respectively. The dominant families and species with an IV (importance value) > 10.00 numbered 6 families and 6 species (23.1% and 9.2% of total), 6 families and 5 species (18.1% and 5%), and 10 families and 7 species (23.3% and 5.7%) in the plantation, secondary, and primary forests, respectively. While the proportions of these IVs were up to 76.1% and 65.2%, 81.0% and 66.2%, and 64.4% and 32.5% of the sum IVs of respective families and species in the corresponding forests. Two-way indicator species analysis (TWINSPAN) divided the plantation, secondary forest, and primary forest into 8, 9, and 8 community groups at the third level, respectively. Diversity and structure indices were significantly higher in the primary forest than in the plantation and secondary forests, except for crown breadth and Simpson index in the plantation. The values of Simpson index and evenness in the plantation were highly significantly higher than in the secondary forest. And the values of density and coverage in the plantation were highly significantly lower than in the secondary forest. Thus, variable disturbance intensity resulted in variation in communities’ composition and diversity characteristics in these forests. Our results may be informative for choosing forest management strategies in the Karst cluster-peak-depression region.

We used field experiments in Hani’s terraced fields in Yuanyang County, Yunnan Province, to compare 23 phenotypic traits of 135 paddy rice landraces, including 66 ones that used to be grown during the 1970s (past-grown landraces) and 69 ones that have been grown during the past decade (current-grown landraces). Comparing 23 phenotypic traits, the average Shannon-Wiener diversity index of the past-grown landraces (H′ = 1.784) was higher than that of the current-grown landraces (H′ = 1.766), while the average coefficients of variation and that of similarity of the past-grown (19.5% and 0.2107, respectively) were lower than those of the current-grown (21.7% and 0.2149, respectively). There were eight and six principal components with eigenvalues > 1 in the past-grown and current-grown landraces, respectively, accounting for 81.4% and 83.2% of their overall variation, respectively. Based on a cluster analysis of the 23 phenotypic traits and a scatter plot of the first three principal components, these landraces could be grouped into two subspecies, indicaand japonica. There was a slightly lower proportion of the indica, waxy, and red pericarp color varieties, as well as strong seed-shattering types in the current-grown landraces than in the past-grown ones. Average plant height, panicle neck length, node length under spike, 1,000-grain weight and flag-leaf angle were all lower in the current-grown. On the other hand, average panicles per plant, flag-leaf width, filled grains per panicle and seed-setting rate increased in the current-grown landraces. In addition, the current-grown landraces had more compact plant types. The simplification and decrease in the genetic diversity of current-grown landraces compared to past-grown landraces may have resulted from the increased use of hybrid rice, selection for high yield traits, and less consideration of the traditional cultural habitude by local ethnic groups. More attention should be paid to both conservation of rice landraces as well as to the traditional rice culture in Yuanyang Hani’s terraced fields in Yunnan Province.

Testacea (or testate amoebae, thecamoebians) are free-living amoeboid protozoa inhabiting a shell or test and they play an important role in material cycle and energy flow in terrestrial and aquatic ecosystems. The fauna of Testacea was analyzed from three polar regions of the Earth (Arctic, Antarctic and Tibet). In total, 315 species from 62 genera were recorded in the polar regions, i.e. 232 species (51 genera) in the Arctic, 131 species (30 genera) in the Antarctic, and 173 species (42 genera) in Tibet. In each polar region, the most diverse genera were Arcella, Centropyxis,Difflugia, Euglypha, Nebela; they accounted for 51.3%, 63.4% and 60.1% of the total species number in the Arctic, Antarctic and Tibet, respectively. Seventy-three species (23.2% of all species) and twenty-four genera (38.7% of all genera) were common to the three polar regions. One hundred and sixty-seven species (53.0% of species) were found only in one of the polar regions. Both Assulina muscorum and Centropyxis aerophila were widely distributed with the highest frequency (90%) in 40 subregions from the Arctic, Antarctic and Tibet. Cluster analysis revealed that the highest species-level similarity of Testacea was between the Arctic and Tibet (56.3%). Further, species similarity was the highest between the Arctic and Tibet based on Arcellinida species data, but the lowest based on filose Testacea species. Distinct differences in Testacea fauna indicate that some species are not ubiquitously distributed in spite of better passive long-distance dispersal than macro-organisms. Geographic distributional patterns of Testacea diversity are closely related to body size, habitat type and historical events, and our perception of these patterns are strongly influenced by taxonomic resolution (morphological criteria), sampling effort and spatial scales. We propose that study of genetic diversity among and within common Testacea morphospecies in relation to ecological and historical factors will elucidate geographic distributional patterns within this interesting group.

To investigate the effects of habitat fragmentation on the use of nest site resources by a secondary cavity-nesting bird species, the great tit (Parus major), we placed 443 artificial nest boxes on 21 islands in Thousand Island Lake from February to August 2008. Among the nest boxes 72 (16.3%) were used by great tits. We analyzed the relationships between island area, island isolation, predator activity, vegetation cover and nest box orientation and the use of nest boxes by great tits. Great tits preferred nest boxes with lower predator activity, lower vegetation cover, and an eastern or southern orientation. Island area and isolation did not affect the use of nest boxes directly, but island area indirectly influenced the use of nest boxes by affecting predator activity. Our results suggest that attention should be paid to environmental variables that directly affect the use of nest site resources by great tits. Our study also highlights the importance of the indirect effects of habitat fragmentation on the use of nest site resources by great tits.

Soil fauna play a key role in regulating carbon allocation and nutrient cycling in terrestrial ecosystems. As soil fauna are sensitive to environmental changes, increases in soil nitrogen (N) availability resulting from global changes may profoundly influence the structure and function of soil faunal communities. However, the response of soil fauna in forest ecosystems to increases in soil N availability is still poorly understood. In order to explore the relationship between soil N availability and soil fauna, we examined the effects of N addition on the density, grouping and feeding habits of soil fauna in larch (Larix gmelinii) and ash (Fraxinus mandshurica) plantations in northeastern China from 2008 to 2009. Our results showed that N addition changed the structure of soil fauna communities in both plantations. After N addition in the larch plantation, densities of soil fauna in surface soil layers (0-10 cm) increased by an average of 12% (July) and 15% (October) in 2008, whereas they decreased by 22% (May) and 20% (July) in 2009. A similar pattern occurred in the ash plantation—densities increased by an average of 14% (July) and 8% (October) in 2008, and decreased by 22% (May) and 9% (July) in 2009. In contrast, densities of soil fauna in subsurface layers (10-20 cm) increased in both plantations only in July of 2008 and then decreased significantly (25% in larch and 21% in ash) in following samples. The number of soil faunal groups increased from 34 to 43 in the larch plantation and from 43 to 48 in the ash plantation post N addition. In both plantations, N addition altered the densities of soil fauna with different feeding habits, with a decrease in soil detritivores and an increase in soil herbivores and no change in soil predators. These findings indicated that increasing soil N availability significantly altered the density, and community composition in terms of feeding habits, of soil fauna in both plantations, thereby potentially influencing belowground carbon allocation and nutrient cycling at the ecosystem level.

Procambarus clarkii is an alien invasive crayfish species that occurs in the major river basins along the middle and lower reaches of the Yangtze River. To understand genetic diversity and population structure of the species in the region, we collected 182 individuals from nine sites in four regions in the Yangtze, Huaihe, and Xin'anjiang River basins in Anhui Province. Using nine pairs of microsatellite markers, we studied the genetic differentiation, genetic structure and genetic clustering pattern of these P. clarkiipopulations. The expected heterozygosity (H_E) was 0.78 while the observed heterozygosity (H_O) was 0.36. Of the nine populations, the highest expected heterozygosity (0.76) was in the Wangjiang population, and the lowest (0.56) was for the Feixi population. Using a Bottleneck Test, we found a significant signal of heterozygote deficiency, indicating a recent decline in these populations. Our studies also showed that there were high levels of gene flow among populations, and a significant correlation found between genetic distance and geographic distance (r= 0.33, P< 0.05). We detected evidence of a significant jump dispersal event between the Xin’anjiang and Chengdonghu populations, thus indicating that human-mediated dispersal has played an important role in the present genetic structure ofProcambarus clarkiipopulation.

The genetic diversity of livestock breeds plays an important role in livestock production, but the significant loss of breeds is threatening genetic diversity of farm animal genetic resources (AnGR). The Weitzman approach which was accepted as a framework for assessment of genetic diversity on AnGR was exploited. In this study, several measurement indexes of genetic diversity, involving total genetic diversity, contributions of each breed to the total diversity, marginal diversities, conservation potential, were calculated based on microsatellite marker data of 20 Central-China type pig populations. Total genetic diversity of twenty Central-China pig breeds was 11,707 and expected diversity was 66.96% of the total genetic diversity. Jinhua pig had the greatest contribution to overall genetic diversity (8.90%), followed by Wannan Spotted pig (7.46%), Shengxian Spotted pig (7.40%), and Leping pig (7.04%). Jinhua pig also had the highest conservation potential (783.53), followed by Shengxian Spotted pig (454.53), Hang pig (366.68), and Large Black-White pig (343.17). Shown as the derived maximum-likelihood tree, the 20 Central-China type pig breeds were clustered into three groups. The pig breeds from Hunan or Hubei Province, such as Daweizi pig, Shaziling pig and Ningxiang pig, formed a group; Nancheng pig clustered with Shengxian Spotted pig and Hang pig; The third cluster was Jinhua pig and Wannan Spotted pig. Furthermore, the advantages and drawbacks of Weitzman approach were discussed. We hope to provide objective and rational criteria and strategy for decision-making in conservation of Central-China type pig breeds.

Cryptic species are morphologically undetected yet genetically divergent species. The presence of cryptic pollinating-fig wasp species has potentially important implications for understanding fig/fig-wasp mutualisms and the coexistence of cryptic species. It is essential to identify cryptic species quickly and accurately using molecular markers since the species are morphologically undistinguishable. We used PCR-RFLP to analyze the mtDNA COI gene in cryptic species of Ceratosolen emarginatusandC. gravelyi. The PCR-RFLP was useful for determining the composition of cryptic pollinating-fig wasp species. Ceratosolen emarginatus included two cryptic species (A and B) with an XhoI and a BssSI digesting site in the COIgene, respectively. Ceratosolen gravelyi included two cryptic species with a BmrI and an AvaI digesting site, respectively. Genomic DNA samples were extracted from a mixture of cryptic species A and B withinC. emarginatus, and XhoI andBssSI endonucleases were used to digest the amplified COIfragments. XhoI-specific fragments were found when cryptic species A was present, and BssSI-specific fragments were found when cryptic species B was present. The digestion of COI gene with BmrI andAvaI in two cryptic species ofC. gravelyi showed similar results. Taken together, PCR-RFLP, based on PCR and DNA restriction enzyme digestion, can quickly and accurately identify cryptic pollinating-fig wasp species.

The composition and diversity of fish species in Quanzhou Bay waters are analyzed based on 2 seasonal surveys in 2008. A total of 54 fish species belonging to 32 families, 13 orders and 2 classes are recorded. According to their living environment, the fishes can be grouped into 3 types, among them 12 species are pelagic fish, 19 are near demersal fish and 23 demersal fish. According to temperature adaptation, the fishes can be divided into 2 types, i.e. 40 species are warm water and the rest 14 are temperate warm water fish. In terms of food habit, they can be grouped into 4 types, of which 4 species of omnivores, 37 lower carnivorous, 8 middle carnivorous and 5 higher carnivorous. Argyrosomus argentatus and Johnius belengerii were the first dominant species in May. Then, they were replaced by Coilia mystus and Harpodon nehereus in October. Comparing with a survey in 1985, we find that the species composition and the dominant species of the bay have changed obviously. The Shannon-Wiener index decreased from 3.05 to 2.32, the Pielou evenness decreased from 0.76 to 0.58, the trophic index decreased from 2.79 to 2.54. It is suggested that factors such as overfishing, water pollution and habitat loss may have reduced the fish diversity of the bay.