中国谷子潜在地理分布的多模型比较

谷子是中国干旱和半干旱区主要的粮食作物之一.它耐旱、耐瘠薄、抗逆性强、适应性广,是未来应对干旱形势的重要战略储备作物.本文基于谷子的157个地理分布点数据,利用中国谷子产量与环境指标的相关性分析,选出10个气候指标、7个土壤指标和3个地形指标,采用MaxEnt、EMFA、RF和GAM共4个物种分布模型,分析中国谷子的潜在适宜性分布.结果表明: 4种模型均可成功模拟谷子的潜在地理分布,其中,MaxEnt模型的模拟效果最好.选用的环境指标中,水热条件对谷子生长最敏感.模型结果结合ArcGIS空间分析模块的结果表明,中国谷子的潜在适宜生长区(最适宜区和适宜区)总面积为55.68×10⁴ km²,远远大于当前谷子的实际种植面积,主要集中在东北地区的东北平原、长白山以南与牡丹江流域,华北地区的淮河以北,华中地区汉江以东与大别山以北,西北地区的黄土高原、鄂尔多斯高原南部、祁连山脉东部、天山山脉东部与阿尔泰山脉,西南地区的重庆以北和贵州西部局地区域.     

Economic impact of combined torrefaction and pelletization processes on forestry biomass supply

The cost of supplying wood biomass from forestry operations in remote areas has been an obstacle to expansion of forest‐based bioenergy in much of the western United States. Economies of scale in the production of liquid fuels from lignocellulosic biomass feedstocks favor large centralized biorefineries. Increasing transportation efficiency through torrefaction and pelletization at distributed satellite facilities may serve as a means to expand the utilization of forestry residuals in biofuel production. To investigate this potential, a mixed‐integer linear program was developed to optimize the feedstock supply chain design with and without distributed pretreatment. The model uses techno‐economic assessment of scale‐dependent biomass pretreatment processes from existing literature and multimodal biomass transportation cost evaluations derived from a spatially explicit network analysis as input. In addition, the sensitivity of the optimal system configuration was determined for variations of key input parameters including the production scale of pretreatment facilities, road and rail transportation costs, and feedstock procurement costs. Torrefaction and densification were found to reduce transportation costs by $0.84 per GJ and overall delivered costs by $0.24 per GJ, representing 14.5% and 5.2% cost reductions compared to feedstock collection without pretreatment. Significant uncertainties remain in terms of the costs associated with deploying torrefaction equipment at the scales modeled, but the level of potential cost savings suggests further analysis and development of these alternatives.     

Linking macroecology and community ecology: refining predictions of species distributions using biotic interaction networks

Macroecological models for predicting species distributions usually only include abiotic environmental conditions as explanatory variables, despite knowledge from community ecology that all species are linked to other species through biotic interactions. This disconnect is largely due to the different spatial scales considered by the two sub‐disciplines: macroecologists study patterns at large extents and coarse resolutions, while community ecologists focus on small extents and fine resolutions. A general framework for including biotic interactions in macroecological models would help bridge this divide, as it would allow for rigorous testing of the role that biotic interactions play in determining species ranges. Here, we present an approach that combines species distribution models with Bayesian networks, which enables the direct and indirect effects of biotic interactions to be modelled as propagating conditional dependencies among species’ presences. We show that including biotic interactions in distribution models for species from a California grassland community results in better range predictions across the western USA. This new approach will be important for improving estimates of species distributions and their dynamics under environmental change.     

Mirror neurons in the tree of life: mosaic evolution,plasticity and exaptation of sensorimotor matching responses

Considering the properties of mirror neurons (MNs) in terms of development and phylogeny, we offer a novel, unifying, and testable account of their evolution according to the available data and try to unify apparently discordant research, including the plasticity of MNs during development, their adaptive value and their phylogenetic relationships and continuity. We hypothesize that the MN system reflects a set of interrelated traits, each with an independent natural history due to unique selective pressures, and propose that there are at least three evolutionarily significant trends that gave raise to three subtypes: hand visuomotor, mouth visuomotor, and audio–vocal. Specifically, we put forward a mosaic evolution hypothesis, which posits that different types of MNs may have evolved at different rates within and among species. This evolutionary hypothesis represents an alternative to both adaptationist and associative models. Finally, the review offers a strong heuristic potential in predicting the circumstances under which specific variations and properties of MNs are expected. Such predictive value is critical to test new hypotheses about MN activity and its plastic changes, depending on the species, the neuroanatomical substrates, and the ecological niche.     

Geographical and environmental gradients of lianas and vines in China

Aim Climbing plants are characterized by long, wide vessel elements, which may be vulnerable to cold‐ or drought‐induced embolism. However, the difference in vulnerability between lianas (woody climbing plants) and vines (herbaceous climbing plants) has not yet been reported. Here we hypothesize that both lianas and vines are more sensitive to variations in water and temperature than are self‐supporting plants. Consequently, the proportions of lianas and vines in flora are expected to decline significantly along geographical and environmental gradients. Location China. Methods A unique dataset describing 82 floras in China was examined. The proportion of lianas in the flora (LPF) and the proportion of vines in the flora (VPF) were calculated independently. The proportion of the climbing plants in total spermatophyte flora (CPF) was also calculated. LPF and VPF were compared along latitudinal, mean annual rainfall (Rain), and mean January temperature (T₁) gradients. Local linear regression analyses showed the changing tendencies of LPF and VPF. Prediction models of LPF using geographical and environmental factors were studied in some subranges. Results (1) LPF was highest in the tropics (13.8% on average), decreased linearly with increasing latitude within the latitude < 42 °N subrange, and reached < 1% north of 42 °N in China. VPF fluctuated slightly from tropical (4.7%), to subtropical (4.2%) to warm temperate (4.5%) regions, but declined significantly in temperate (3.2%) and dry (1.5%) zones in China. (2) LPF decreased significantly with decreasing rainfall, and decreased significantly with decreasing T₁ in areas where T₁ > −10 °C. In contrast, VPF tended to be constant in areas where T₁ > −5 °C or Rain > 1000 mm, and declined under extreme water or temperature stresses. (3) Predictions of LPF using Rain and T₁ in areas where T₁ > −10 °C, and using latitude and altitude within the latitude < 42 °N subrange were both reliable. According to the geographical model for LPF and a constant VPF, tropical Asian forests would have a LPF as high as 25.4% and the highest CPF would be c. 30%. Conclusions We conclude that liana diversity is more sensitive to temperature and water availability than that of vines and other plants. Geographical and environmental gradients affected LPF but not VPF. Shorter life spans and underground nutrient storage may be effective strategies adopted by vines to avoid drought and cold stresses.     

Occurrence of three distinct begomoviruses in cassava in Madagascar

The presence of East African cassava mosaic virus in association with cassava mosaic disease in Madagascar has previously been reported. We now describe virus isolates from mosaic‐affected Madagascan cassava with epitope profiles typical of African cassava mosaic virus, and an isolate with a nucleotide sequence similar to that of South African cassava mosaic virus. Thus, three distinct begomoviruses occur in cassava in Madagascar.