Main drivers of plant diversity patterns of rubber plantations in the Greater Mekong Sub-region

The Greater Mekong Sub-region (GMS) is one the global biodiversity hotspots. However, the diversity has been seriously threatened due to environmental degradation and deforestation, especially by expansion of rubber plantations. Yet, little is known about the impact of rubber plantations on plant diversity. In this study, we analyzed plant diversity patterns of rubber plantations in the GMS based on a ground survey of a large number of samples. We found that diversity varied across countries due to varying agricultural intensities. Laos had the highest diversity, then followed China, Myanmar, Cambodia. Thailand and Vietnam were the lowest among them. Plant species richness of Laos was about 1.5 times that of Vietnam. We uncovered latitudinal and longitudinal gradients in plant diversity across these artificial forests of rubber plantations. These gradients could be explained by the traditional ecological theories. Furthermore, null deviation of observed community to the randomly assembled communities were larger than zero indicating deterministic process were more important for structuring the community. Meanwhile, the results also showed that higher dominance of some exotic species (such as Chromolaena odorata and Mimosa pudica) were associated with a loss of plant diversity within rubber plantations. In conclusion, not only environmental factors (such as elevation and latitude), but also exotic species were the main factors affecting diversity of these artificial stands. Much more effort should be made to balance agricultural production with conservation goals in this region, particularly to minimize the diversity loss in Vietnam and Cambodia.

Genetic diversity patterns of human ethnic groups as inferred from the 1000 genomes

Human genetic diversity remains to be better understood. We here analyzed data from the 1000 Genomes Project and defined group specific fixed alleles (GSFAs) as those that are likely fixed in one ethnic group but non-fixed in at least one other group. The fraction of derived alleles in GSFAs indicates relative distance to apes because such alleles are absent in apes. Our results show that different groups differed in GSFA numbers consistent with known genetic diversity patterns, but also differed in the fraction of derived alleles in GSFAs throughout the entire genome, with East Asians having the largest fraction, followed by South Asians, Europeans, Native Americans, and Africans. Fast evolving sites such as intergenic regions were enriched with derived alleles and showed greater differences in GSFA numbers between East Asians and Africans. Furthermore, GSFAs in East Asians are mostly not fixed in other groups especially Africans, which was particularly more pronounced for fast evolving noncoding variants, while GSFAs in Africans are mostly also fixed in East Asians. Finally, variants that are likely non-neutral such as those leading to stop codon gain/loss and splice donor/acceptor gain/loss showed patterns similar to those of fast-evolving noncoding variants. These results can be accounted for by the maximum genetic diversity theory but not by the neutral theory or its inference that Eurasians suffered bottlenecks, and have implications for better management of group specific genetic diseases.

Elevational Diversity Patterns of Green Lacewings (Neuroptera: Chrysopidae) Uncovered With DNA Barcoding in a Biodiversity Hotspot of Southwest China

Elevational diversity patterns can reflect the responses of biodiversity to climate change spatially. We investigate the species diversity patterns of green lacewings (an important predatory group of insects) along the gradient of elevation from the Shaluli Mountains (Mts. Shaluli), which belong to the Hengduan Mountains in southwestern China, one of the important hotspots of global biodiversity. We combined multiple approaches, including Automatic Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning analysis (ASAP), General Mixed Yule Coalescent (GMYC), Poisson tree processes (bPTP), multi-rate Poisson tree processes (mPTP), to delimit the green lacewings species based on the standard barcoding region of cytochrome c oxidase subunit I (COI). The α-diversity and β-diversity patterns of green lacewings from the Mts. Shaluli along the gradient of elevation were analyzed, with further exploration on how the temperature effect elevational-diversity pattern on broad-scale (county scale) elevational gradients. The DNA barcoding reference library consisted of 40 green lacewing species from the Mts. Shaluli. The α-diversity of green lacewings decreased with the increasing elevation. The temperature was found to have a significant effect on the abundance and Shannon-Wiener diversity index but not on the species richness. Nestedness replaced turnover as the main component of Sørensen’s dissimilarity with the increasing elevation, and greater nestedness occurred at low temperature areas. The combination of a reliable DNA barcoding database could improve the accuracy and efficiency to investigate the species diversity patterns of green lacewings. Temperature, resource, and resultant interspecific competitions may have important roles in explaining the species diversity patterns of green lacewings from the Mts. Shaluli. Priority of conservation should be given to the species at low elevation, middle elevation, and relatively high temperature regions under the background of global climate warming.

Marine diversity patterns in Australia are filtered through biogeography

Latitudinal diversity gradients are among the most striking patterns in nature. Despite a large body of work investigating both geographic and environmental drivers, biogeographical provinces have not been included in statistical models of diversity patterns. Instead, spatial studies tend to focus on species–area and local–regional relationships. Here, we investigate correlates of a latitudinal diversity pattern in Australian coastal molluscs. We use an online database of greater than 300 000 specimens and quantify diversity using four methods to account for sampling variation. Additionally, we present a biogeographic scheme using factor analysis that allows for both gradients and sharp boundaries between clusters. The factors are defined on the basis of species composition and are independent of diversity. Regardless of the measure used, diversity is not directly explained by combinations of abiotic variables. Instead, transitions between regions better explain the observed patterns. Biogeographic gradients can in turn be explained by environmental variables, suggesting that environmental controls on diversity may be indirect. Faunas within provinces are homogeneous regardless of environmental variability. Thus, transitions between provinces explain most of the variation in diversity because small-scale factors are dampened. This explanation contrasts with the species-energy hypothesis. Future work should more carefully consider biogeographic gradients when investigating diversity patterns.