Contribution to the orchid flora of South Central Africa

11 new taxa (8 new species, 3 new varieties) ofOrchidaceae are described from South Central Africa, including data on their habitat and distribution and discussions of their systematic affinities.     

Biotic diversification in the Guayana Highlands: a proposal

Until recently, the high degree of diversity and endemism of the Guayana Highlands was explained within the frame of the refuge theory. Although this hypothesis is unsupported by recent palaeoecological evidence, no new diversification model has been proposed. This paper is a proposal based on the latest palynological findings that indicate a downward biotic migration of c. 1100 m altitude during glacials, and the subsequent interglacial upward shift, in response to colder and warmer climates, respectively. Therefore, during glacials, biotic mixing is expected in the lowlands, thus promoting sympatric speciation, hybridization and polyploidy. At the mountaintops, unknown cold‐adapted taxa and páramo‐like(?) communities are expected to have occurred, and vicariance prevailed. In the interglacials, many taxa have had the opportunity for ascending to the mountains again, allowing genetic interchange among their slopes and summits, while others would have been adapted to lowlands. The interglacial highland communities, where vicariance still predominated, experienced some extinction owing to habitat loss by upland displacement. According to this model, the successive alternation of glacials and interglacials resulted in a net increase of diversity and endemism, favoured by the complex topography and habitat heterogeneity, which allowed high niche diversification. This model has some similarities with the Andean and Amazon modes of diversification, but the special topographical characteristics of the Guayana region made it different in other fundamental aspects. The Guayana Highlands would have acted as a ‘biodiversity pump’ for the surrounding inner and coastal lowlands, due to the repeated speciation and further spreading events, as a response to climate. Several working hypotheses are suggested in relation to the proposed model. The use of coordinated international multiproxy projects combining palaeoecology and genetic analysis of modern taxa is strongly encouraged for exploring these ideas.     

A new pipoid frog (Anura,Pipimorpha) from the Paleogene of Patagonia. Paleobiogeographical implications

The aim of the present contribution is to describe a new genus and species of Pipoidea from the Huitrera Formation (Eocene) from Patagonia, Argentina. The new genus shows a unique combination of characters indicating that it is a valid taxon different from other pipimorphs, including the coeval Llankibatrachus truebae. The phylogenetic analysis resulted in the nesting of the new taxon within a previously unrecognized endemic clade of South American aglossans. This new clade turns out to be the sister-group of crown-group Pipidae. This phylogenetic proposal reinforces the hypothesis sustaining the dispersal of pipids between Africa and South America through an island chain or a continental bridge across the Atlantic Ocean by Early Tertiary times.     

风景园林视角下的南粤古驿道规划设计研究

游径系统一直是广东城乡规划建设的亮点,也是推动高质量发展与高水平保护的重要手段。以广东省绿道建设和古驿道建设为例,通过厘清两类游径的缘起和作用,总结风景园林专业力量在绿道建设实施过程中形成的风景园林遗产保护、大地景观规划、园林与景观设计、园林工程与技术、园林植物应用、景观生态学等专业设计之“道”,提出在南粤古驿道建设的大背景下,风景园林人应充分发挥风景园林专业优势,以“道”传“道”,将绿道专业设计之“道”传承到南粤古驿道建设中去,推动南粤古驿道建设高质量发展,同时为风景园林专业设计人员以南粤古驿道为载体进行景观创作提供路径与方法。     

Distribution of Karlodinium veneficum in the coastal region of Xiangshan Bay in the East China Sea,as detected by a real-time quantitative PCR assay of ribosomal ITS sequence

Athecate dinoflagellate Karlodinium veneficum is a universal toxic species possessing karlotoxins recognized especially as ichthyotoxic as well as cytotoxic and hemolytic. Blooms of K. veneficum, both single-species or accompanied with other species, occurred more frequently worldwide in recent years, including the coastal region of China. Normally, K. veneficum present in relatively low abundance in phytoplankton communities in estuary regions. Being small and difficult to identify with light microscopy, it has been ignored for a long time till its blooming and toxins being confirmed. How it presents in background level and what is its relationship with critical geological and hydrological environment factors are basically not clear. In this study, the paper reports the application of a real-time quantitative PCR (qPCR) method to investigate the abundance and distribution of K. veneficum in the coastal waters of Xiangshan Bay in the East China Sea (ECS), a typical bay area of harmful algae blooms and heavily affected by anthropogenic activities. The real-time qPCR assay came out being an efficient method at detecting even low cell densities of K. veneficum of different genotypes. A total of 38 field samples of surface (0.5 m) and bottom water (9–100 m in depth) were analyzed and 12 samples were found positive for K. veneficum. At least 3 genotypes of K. veneficum present in this region. Temperatures in sites of K. veneficum positive ranged from 21.7 to 23.4 °C, and salinity levels were between 21.1 and 26.3. The K. veneficum distributed quite extensively in the waters of Xiangshan Bay, cell abundance varied from a low of 4 cells/L to a maximum of 170 cells/L. Most of the samples containing K. veneficum were collected from bottom water in different sites. At three of the 19 sampling sites, K. veneficum was detected in both surface and bottom water samples. Especially at sampling site near Beilun port, where the water is typically muddy with low transparency, relative high cell numbers of K. veneficum were found in both surface and bottom waters. Mixotrophy and vertical migration of K. veneficum could be important eco-physiological factors to consider in terms of understanding these distribution characteristics. The ideal conditions for K. veneficum growth and aggregation in this area still needs further study.     

1980s-2010s华北夏谷区主栽谷子品种SSR遗传多样性分析

通过对20世纪80年代以来具有代表性的华北夏谷区审(鉴)定的20个主栽谷子品种进行SSR标记多态性分析,研究了华北地区育成谷子品种的遗传多样性。49对引物在20个谷子品种中扩增出具有多态性的条带,共检测出142个等位变异,平均每个位点检测出的等位变异数为2.96个。标记位点多态性信息含量(PIC)变幅为0.0904～0.6896,平均为0.4168。20份材料间的遗传距离变幅为0.0173～0.9000,聚类分析将其分成3个类群,其中谷丰1号自成一类,表明谷丰1号的遗传距离较其他品种大。不同年代谷子品种间遗传距离分析结果显示,各年代品种之间的平均遗传距离由大到小依次是1980s>1990s>2000s>2010s,表明随着年代的递进育成品种的遗传差异减小,亲缘关系增近。     

Genome Characteristics and Evolution of Pseudorabies Virus Strains in Eastern China from 2017 to 2019

Since late 2011, outbreaks of pseudorabies virus(PRV) have occurred in southern China causing major economic losses to the pig industry. We previously reported that variant PRV forms and recombination in China could be the source of continued epidemics. Here, we analyzed samples from intensive pig farms in eastern China between 2017 and 2019, and sequenced the main glycoproteins(gB, gC, gD, and gE) to study the evolution characteristics of PRV. Based on the g C gene, we found that PRV variants belong to clade 2 and detected a founder effect during by the PRV epidemic. In addition,we detected inter-and intra-clade recombination; in particular, inter-clade recombination in the g B genes of strains FJ-ZXF and FJ-W2, which were recombinant with clade 1 strains. We also found specific amino-acid changes and positively selected sites, possibly associated with functional changes. This analysis of the emergence of PRV in China illustrates the need for continuous monitoring and the development of vaccines against specific variants of PRV.