Functional divergence of two duplicated Fertilization Independent Endosperm genes in rice with respect to seed development

Fertilization Independent Endosperm (FIE) is an essential member of Polycomb Repressive Complex 2 (PRC2) that plays important roles in the developmental regulation of plants. OsFIE1 and OsFIE2 are two FIE homologs in the rice genome. Here, we showed that OsFIE1 probably duplicated from OsFIE2 after the origin of the tribe Oryzeae, but has a specific expression pattern and methylation landscape. During evolution, OsFIE1 underwent a less intensive purifying selection than did OsFIE2. The mutant osfie1 produced smaller seeds and displayed reduced dormancy, indicating that OsFIE1 predominantly functions in late seed development. Ectopic expression of OsFIE1, but not OsFIE2, was deleterious to vegetative growth in a dose‐dependent manner. The newly evolved N‐terminal tail of OsFIE1 was probably not the cause of the adverse effects on vegetative growth. The CRISPR/Cas9‐derived mutant osfie2 exhibited impaired cellularization of the endosperm, which suggested that OsFIE2 is indispensable for early seed development as a positive regulator of cellularization. Autonomous endosperm was observed in both OsFIE2^+? and osfie1/OsFIE2^+? but at a very low frequency. Although OsFIE1‐PRC2 exhibited H3K27me3 methyltransferase ability in plants, OsFIE1‐PRC2 is likely to be less important for development in rice than is OsFIE2‐PRC2. Our findings revealed the functional divergence of OsFIE1 and OsFIE2 and shed light on their distinct evolution following duplication.     

IPBES框架下的生物多样性和生态系统服务区域评估及政策经验

生物多样性和生态系统服务为人类的生计和良好的生活质量奠定了重要基础。然而, 越来越多的研究表明, 生物多样性和生态系统服务在全球范围内的持续下降使自然对人类的贡献大幅降低。多尺度评估能够说明不同尺度下生物多样性的现状, 有利于制定适合区域特点、符合国情的决策建议。2013年12月, 生物多样性和生态系统服务政府间科学政策平台(Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, IPBES)通过第一轮工作方案, 决定开展“区域/次区域生物多样性和生态系统服务评估”(简称“区域评估”), 即评估亚洲-太平洋(简称亚太)、美洲、非洲以及欧洲-中亚四大地理区域的生物多样性和生态系统服务。区域评估报告及其决策者摘要已在IPBES第六次全体会议上(2018年3月, 哥伦比亚麦德林)审议通过。本文概述了四大地理区域的生物多样性的重要性、生物多样性保护领域取得的进展、面临的主要危机和机遇, 探讨了评估对其他国际进程的影响, 综合分析了各区域生物多样性和生态系统服务的特点以及各区域评估结果的差别, 总结了评估的政策经验, 以期为中国的生物多样性保护提供科学参考。     

西双版纳国家级自然保护区蚂蚁-树互作网络空间变异

网络分析(network analysis)可以同时分析群落中的物种多样性和种间关系, 为了解生态群落的稳定性机制提供了新的分析思路和方法。本研究从西双版纳国家级自然保护区的纳板河、勐仑和勐腊(补蚌)三个地点采集了树栖性蚂蚁及树木的种类和数量数据, 对蚂蚁-树组成的二分网络进行了分析, 探讨了3个采样点物种的多样性、网络指标以及群落指标之间的关系。我们采用零模型的方法比较了3个样点的标准化网络参数差异。结果表明: 蚂蚁和树木的物种数以及树的异质性指数(Shannon-Wiener多样性指数、Simpson多样性指数)都呈现出勐仑 > 纳板河 > 补蚌的趋势。树木-蚂蚁的灭绝曲线系数大小关系同样为勐仑 > 纳板河 > 补蚌, 灭绝曲线与树的物种数及异质性指数大小趋势一致, 而与蚂蚁的异质性指数并不吻合。根据Z值的绝对值来看, 网络参数(加权嵌套性、平均连接数、特化水平、模块性、连接度)与群落参数(灭绝曲线系数、生态位重叠)的大小趋势相同, 表现出勐仑 > 纳板河 > 补蚌的趋势。综上所述, 蚂蚁-树互作网络的稳定性(灭绝曲线系数)主要由树的数量和异质性指数决定。网络的加权嵌套性和网络中节点的平均连接数也能促进群落的稳定性。而在一个特化的(数值越大表示专性互作越多)和模块化(具有较多密切互作的节点单元)的网络中, 当低营养级物种灭绝时高营养级物种数量将迅速减少。     

播种季节和种植方式对多年生苦荞主要农艺性状的影响

该研究选取六个多年生苦荞新品系,对春季、秋季直播与秋季再生其主要农艺性状进行调查。结果表明:(1)不同播种季节对多年生苦荞新品系主花序的花粉可育率、总结实率、有效结实率、植株株高、主茎粗、主茎分枝数、主茎节数、籽粒百粒重、单株粒数、单株产量的影响均达到显著或极显著水平;秋播主花序花粉可育率、总结实率、有效结实率、植株主茎分枝数、籽粒百粒重、单株粒数、单株产量均极显著高于春播;植株株高、主茎粗、主茎节数均极显著低于春播;主花序花朵大小、籽粒种子长宽比无显著差异。(2)不同种植方式对主花序花粉可育率、有效结实率、植株主茎节数及籽粒百粒重的影响达到显著或极显著水平;秋季再生主花序花粉可育率、籽粒单株粒数显著高于秋季直播;主花序有效结实率、植株主茎粗、主茎节数、籽粒百粒重显著低于秋季直播;主花序花朵大小、总结实率、植株株高、主茎分枝数、籽粒种子长宽比、单株产量无显著差异;相关分析表明,各生长季节下主花序有效结实率及单株粒数与单株产量的相关系数均最高。(3)所有参试品系中,1612-241秋季直播的单株产量显著高于其他品系; 1612-16、1612-33秋季再生单株产量较正季优势显著。该研究结果有助于筛选出适宜一季播种两季收获的优良品系,为今后多年生苦荞的选择育种提供线索基础。     

一株降解煤油菌株的筛选与鉴定

本文通过从污水处理厂活性污泥中分离得到一株高效降解轻油(煤油)细菌5092-2,通过形态学、16S rRNA鉴定该菌为Mangroveibacter sp.。进一步对其生长条件进行了研究,发现该菌在23℃到38℃、pH为5.0到9.0范围内生长无明显差异。在温度为35℃,pH 7.2~7.4,160 r/min培养7 d,菌株降解煤油的能力达到52.3%,具有进一步研究的价值。     

Energy–water and seasonal variations in climate underlie the spatial distribution patterns of gymnosperm species richness in China

Studying the pattern of species richness is crucial in understanding the diversity and distribution of organisms in the earth. Climate and human influences are the major driving factors that directly influence the large‐scale distributions of plant species, including gymnosperms. Understanding how gymnosperms respond to climate, topography, and human‐induced changes is useful in predicting the impacts of global change. Here, we attempt to evaluate how climatic and human‐induced processes could affect the spatial richness patterns of gymnosperms in China. Initially, we divided a map of the country into grid cells of 50 × 50 km² spatial resolution and plotted the geographical coordinate distribution occurrence of 236 native gymnosperm taxa. The gymnosperm taxa were separated into three response variables: (a) all species, (b) endemic species, and (c) nonendemic species, based on their distribution. The species richness patterns of these response variables to four predictor sets were also evaluated: (a) energy–water, (b) climatic seasonality, (c) habitat heterogeneity, and (d) human influences. We performed generalized linear models (GLMs) and variation partitioning analyses to determine the effect of predictors on spatial richness patterns. The results showed that the distribution pattern of species richness was highest in the southwestern mountainous area and Taiwan in China. We found a significant relationship between the predictor variable set and species richness pattern. Further, our findings provide evidence that climatic seasonality is the most important factor in explaining distinct fractions of variations in the species richness patterns of all studied response variables. Moreover, it was found that energy–water was the best predictor set to determine the richness pattern of all species and endemic species, while habitat heterogeneity has a better influence on nonendemic species. Therefore, we conclude that with the current climate fluctuations as a result of climate change and increasing human activities, gymnosperms might face a high risk of extinction.     

Genetic diversity and population structure of Quercus fabri Hance in China revealed by genotyping‐by‐sequencing

Analysis of genetic diversity and population structure among Quercus fabri populations is essential for the conservation and utilization of Q. fabri resources. Here, the genetic diversity and structure of 158 individuals from 13 natural populations of Quercus fabri in China were analyzed using genotyping‐by‐sequencing (GBS). A total of 459,564 high‐quality single nucleotide polymorphisms (SNPs) were obtained after filtration for subsequent analysis. Genetic structure analysis revealed that these individuals can be clustered into two groups and the structure can be explained mainly by the geographic barrier, showed gene introgression from coastal to inland areas and high mountains could significantly hinder the mutual introgression of genes. Genetic diversity analysis indicated that the individual differences within groups are greater than the differences between the two groups. These results will help us better understand the genetic backgrounds of Q. fabri.     

Shifts in potential geographical distribution of Pterocarya stenoptera under climate change scenarios in China

Climate change poses a serious threat to biodiversity. Predicting the effects of climate change on the distribution of a species' habitat can help humans address the potential threats which may change the scope and distribution of species. Pterocarya stenoptera is a common fast‐growing tree species often used in the ecological restoration of riverbanks and alpine forests in central and eastern China. Until now, the characteristics of the distribution of this species' habitat are poorly known as are the environmental factors that influence its preferred habitat. In the present study, the Maximum Entropy Modeling (Maxent) algorithm and the Genetic Algorithm for Ruleset Production (GARP) were used to establish the models for the potential distribution of this species by selecting 236 sites with known occurrences and 14 environmental variables. The results indicate that both models have good predictive power. Minimum temperature of coldest month (Bio6), mean temperature of warmest quarter (Bio10), annual precipitation (Bio12), and precipitation of driest month (Bio14) were important environmental variables influencing the prediction of the Maxent model. According to the models, the temperate and subtropical regions of eastern China had high environmental suitability for this species, where the species had been recorded. Under each climate change scenario, climatic suitability of the existing range of this species increased, and its climatic niche expanded geographically to the north and higher elevation. GARP predicted a more conservative expansion. The projected spatial and temporal patterns of P. stenoptera can provide reference for the development of forest management and protection strategies.     

Is population subdivision different from speciation? From phylogeography to species delimitation

Species‐level diversity and the underlying mechanisms that lead to the formation of new species, that is, speciation, have often been confounded with intraspecific diversity and population subdivision. The delineation between intraspecific and interspecific divergence processes has received much less attention than species delimitation. The ramifications of confounding speciation and population subdivision are that the term speciation has been used to describe many different biological divergence processes, rendering the results, or inferences, between studies incomparable. Phylogeographic studies have advanced our understanding of how spatial variation in the pattern of biodiversity can begin, become structured, and persist through time. Studies of species delimitation have further provided statistical and model‐based approaches to determine the phylogeographic entities that merit species status. However, without a proper understanding and delineation between the processes that generate and maintain intraspecific and interspecific diversity in a study system, the delimitation of species may still not be biologically and evolutionarily relevant. I argue that variation in the continuity of the divergence process among biological systems could be a key factor leading to the enduring contention in delineating divergence patterns, or species delimitation, meriting future comparative studies to help us better understand the nature of biological species.