末次盛冰期以来观光木的潜在地理分布变迁

观光木(Tsoongiodendronodorum)是木兰科的古老残遗物种,目前正面临严峻的生存威胁,属于极小种群濒危植物。通过生态位模型(ENM)能够重建观光木地理分布格局的历史变迁,探究气候变化对该物种分布的影响,并了解其地理分布与气候需求间的关系,从而为全球变暖背景下观光木的保护提供理论基础。该文基于96条现代分布记录和8个环境变量,采用最大熵(MaxEnt)模型模拟观光木在末次盛冰期、全新世中期、现代和未来(2061–2080年,RCP8.5)的潜在分布区,利用SDM toolbox分析观光木的地理空间变化,并综合贡献率、置换重要值和Jackknife检验来评估气候因子的重要性。研究结果表明:(1)观光木的高度适生区在南岭地区,末次盛冰期时没有大尺度向南退缩,很可能在山区避难所原地存活;(2)在全新世中期和未来两个增温的气候情境下,观光木的分布区均表现为缩减,其中未来分布的减幅更大,表明气候变暖对观光木的生长有一定的负面影响;(3)总体上看,观光木各个时期的地理分布范围相对稳定,说明观光木对气候变化有一定的适应能力,人为活动或自身繁育问题可能是致濒的重要原因,并建议对广东和广西群体进行优先保护。     

末次冰盛期以来香果树潜在地理分布格局变迁

香果树是中国特有的单种属孑遗树种,探讨末次冰盛期以来香果树在中国的潜在地理分布格局及其变化,对研究茜草科乃至中国亚热带植物区系的系统发育、古生态和古气候变迁等具有重要作用。研究基于最大熵MaxEnt模型与ArcGIS空间分析技术,利用香果树分布点位信息与气候数据,构建其在末次冰盛期(LGM)、全新世中期(MID)、当前(1960—1990年)以及未来(2061—2080年)的潜在地理分布格局,探明其分布格局的变化趋势,揭示引起其潜在地理分布格局改变的关键因子。结果表明,香果树当前适生区总面积约197.575×10⁴ km²,主要位于中国亚热带地区,其中高适生区集中分布于四川盆周山地、武陵山与武夷山地区,最干季度平均温、最湿月降水量、最冷季度降水量是限制其分布的主要气候因子。末次冰盛期时香果树广泛分布于中国亚热带地区,随后适生区开始缩减且向内陆退缩,全新世中期后适生区面积继续缩减并向高纬度地区迁移。随着全球气候变暖,在不同排放情景下香果树适宜生境面积均进一步缩减并向西与高纬度地区迁移。总体而言,从末次冰盛期至未来,香果树适生区呈现持续缩减并向西...     

小叶栎分布格局对末次盛冰期以来气候变化的响应

小叶栎(Quercus chenii)是华东植物区系的代表树种, 具有很高的生态、经济价值。为重建冰期以来小叶栎地理分布格局的变迁历史、了解环境因子对潜在地理分布的制约机制, 为小叶栎种质资源保护和管理提供科学依据, 该研究基于55条分布记录和8个环境变量, 利用MaxEnt模型模拟小叶栎在末次盛冰期、全新世中期、现代和2070年(温室气体排放情景为典型浓度目标8.5)的潜在分布区, 利用多元环境相似度面和最不相似变量分析探讨气候变迁过程中环境异常区域和引起潜在地理分布改变的关键因素, 综合应用贡献率及置换重要值比较、Jackknife检验评估制约现代地理分布的主要因子, 采用响应曲线确定环境变量的适宜区间。研究结果表明: MaxEnt模型的预测准确度极高, 受试者工作特征曲线下的面积(AUC值)达0.9869 ± 0.0045; 现代高度适宜区在安徽南部、浙江西部、江西东北部和湖北东部; 影响小叶栎地理分布的主要气候因子为气温和降水量, 气温更重要; 最干季平均气温可能是制约小叶栎向北分布的关键因素; 末次盛冰期时, 小叶栎高度适宜区位于东海大陆架内; 全新世中期适宜分布区轮廓已与现代近似; 2070年适宜分布区向北移, 高度适宜区面积增大, 与末次盛冰期、全新世中期和现代相比, 这一时期的气候异常程度最高。气温季节变化和降水季节变化可能是引起地理分布变迁的重要气候因素。     

多星韭分布格局对末次盛冰期以来气候的响应

该研究以分布区主要在横断山脉的多星韭为对象,基于最大熵模型(MaxEnt)和地理信息系统(ArcGIS)模拟了多星韭在末次盛冰期、全新世中期、当前以及未来的分布格局,以探讨多星韭对末次盛冰期以来气候变化的响应。结果显示:(1)多星韭当前的分布区主要受到最暖季度降水量、年均温变化范围和温度季节性变化标准差3个气候因子的影响;海拔对多星韭的当前分布也有着较大的影响。(2)最大熵模型的模拟精度较高(AUC=0.98)。(3)根据多星韭各个时期分布面积的变化得出多星韭与部分高山植物相似,相比当前的分布,多星韭末次盛冰期的分布区发生了较为明显的扩张。研究推测,未来多星韭的分布区将向西移动。     

末次盛冰期以来陀螺果潜在地理分布格局变迁预测

陀螺果(Melliodendron xylocarpum Handel-Mazzetti)为中国特有种,观赏价值极高,了解陀螺果潜在地理分布格局对气候变化的响应对于有效保护和合理利用其野生资源具有重要意义。本文采用ENMeval数据包优化Maxent模型参数设置;基于137条现代地理分布记录和8个生物气候变量模拟和预测陀螺果在末次盛冰期、全新世中期、现在和典型浓度目标(RCP)8.5背景下2070年的潜在分布区;利用多元相似度面和最不相似变量分析,评估气候异常程度和引起气候异常的关键因子;综合使用贡献率、重要值和Jackknife法,检验评估环境因子的重要性。结果表明:当特征组合为线性、二次型、片段化、乘积型和阈值性,调控倍频为2时,模型复杂度和过拟合程度较低,此时测试集受试者工作特征曲线下的面积值达到0.9853±0.0055,模拟准确度极高;陀螺果现代高度适宜区位于广西、广东和湖南交界的地区;末次盛冰期其适宜分布区面积明显缩小,中国南部的适宜区向南转移;全新世中期适宜分布区面积增加,但无明显移动;2070年低海拔地区年均温和极端最高温最异常,适宜度显著降低,生境呈破碎化趋势,高、中度适宜区残存于高海拔地区;温度因子和降雨因子共同制约着陀螺果现代潜在地理分布,但前者更有可能引起地理分布的变迁。     

末次盛冰期以来云南异龙湖的环境演变——来自地球化学沉积记录的证据

通过对云南异龙湖4.56 m沉积岩芯进行X射线荧光光谱分析(XRF),结合13个AMS14C测年结果,获得了高分辨率元素地球化学序列。异龙湖岩芯中元素的因子分析显示,F1因子揭示了沉积地球化学元素的来源,其正载荷代表了流域外源物质输入加强,而负载荷则指示了湖泊自生碳酸盐沉淀的增加,F2因子指示了湖泊氧化还原状态,F3因子可能与人类活动有关。在此基础上结合磁化率、矿物组成及有机质含量等指标,对异龙湖沉积环境演化过程进行探讨。结果表明,在末次盛冰期期间(26000—17000 cal. yr. BP),区域气候特征是气温低、降水少;在17000—14500 cal. yr. BP期间,异龙湖经历了显著的干旱气候,可能与亚洲夏季风突然减弱有关; 14500—9000 cal. yr. BP,异龙湖经历了显著的高湖面阶段,与滇池高水位时期基本一致,表明流域降水丰沛,外源物质输入增加; 9000—6000 cal. yr. BP期间,区域温度增加导致流域干旱化加剧,此阶段与西南地区全新世大暖期(全新世适宜期)相对应; 6000 cal. yr. BP以后外援物质输入锐减可能指示了区域降水的降低。异龙湖地球化学沉积记录揭示的环境演变过程与区域气候环境变化具有一致性,也具有明显的特殊性。     

末次盛冰期以来气候变化对中国山荆子分布格局的影响

山荆子(Malus baccata (L.) Borkh.)具有较高的观赏、经济价值,是苹果属(Malus)植物的重要种质资源。本文利用ENMeval数据包调整Max Ent模型的调控倍频和特征组合参数,根据602条现代分布记录和筛选的8个生物气候变量,模拟预测山荆子在末次盛冰期、中全新世、现代、2070年(RCP 8.5) 4个时期的潜在分布区。采用贡献率、置换重要值比较和刀切法进行检验,综合分析各环境变量对山荆子潜在地理分布的影响。结果显示,当RM值为2、FC为LQHPT时,Max Ent模型的复杂度和过拟合程度较低,该参数下AUC值的均值为0.9272±0.0019,表明模型预测极准确;山荆子现代高度适生区为山西的太行山、管涔山和吕梁山,吉林、辽宁东北部,陕甘宁交界处,河北北部,鲁中南地区;末次盛冰期山荆子适生区整体上显著向东南偏移,北方的高度适生区消失;中全新世适生区轮廓与现代基本一致,但略微有向高海拔地区收缩的趋势; 2070年山荆子在国内的适生区将向高海拔地区急剧收缩,中度、高度适生区面积急剧减少;山荆子现代潜在地理分布受温度和降水因子的共同影响,但后者的影响更大。本研究预测气候变化对山荆子分布范围的影响,将对其种质资源保护和管理提供重要的参考价值。     

中国中全新世（6Ka BP）和末次盛冰期（18Ka BP）生物群区的重建

利用中国第四纪孢粉数据库提供的 116个 6kaBP (± 5 0 0年 )和 39个 18kaBP (± 2ka)的花粉数据 ,根据生物群区化方法 (biomization)重建了中国中全新世 (6kaBP)和未次盛冰期 (18kaBP)两个关键时段的生物群区。结果表明 ,中全新世东部森林系统地向北推进 ,温带落叶阔叶林向北推进约 4个纬度。大部分森林明显向草原区推进 ,青藏高原的冻原大面积退缩 ,在西南地区局部和热带地区气候较今略为冷湿 ,热带季雨林转变为热带雨林。末次盛冰期 ,草原大面积向南扩张 ,抵达现代的常绿阔叶林区的北缘 ,热带森林消失 ,常绿阔叶林退缩到现代热带区域边缘。     

基于Maxent模型的檵木分布格局模拟

应用最大熵模型(Maxent)模拟檵木(Loropetalum chinense)在末次间冰期(last inter glacial, LIG)、末次盛冰期(last glacial maximum, LGM)和当代(Present)等不同时期的中国潜在分布格局,分析影响其分布的主导生物气候因子。结果显示:(1)历史气候的变迁,檵木由末次间冰期经末次盛冰期进入当代,适生区面积呈现增加趋势。当代适生区面积占比最大,适生程度也较高;(2)训练数据和测试数据的AUC值分别为0.947和0.954,均达到了极高的精度;(3)刀切法检测表明,影响檵木分布的主导环境因子依次为bio14(最干月份平均降雨量)、bio17(极干季降雨量)、为bio19(极冷季平均降雨量)和bio15(湿度变化方差),其适生值范围分别是23—93 mm, 98—300 mm, 110—350 mm和42%—65%;(4)较纬度而言,经度是影响我国檵木分布格局的主要因子;(5)我国檵木当代的潜在地理分布主要在北回归线以北的区域,总面积为162.55万km²,占国土总面积的16.93%,高适生区集中于...     

观光木群落优势树种生态位和种间联结

为了解君子峰自然保护区极小种群观光木群落的种间关系和生态联系,加强观光木野生资源的保护,对群落优势树种的生态位特征和种间联结性进行研究。结果表明: 观光木、浙江润楠、木荷、赤杨叶的生态位宽度优势明显,是主要建群种;20个优势树种的190组种对中,有50.5%的种对生态位重叠值大于0.5,物种间生态位分化程度一般;观光木与其他19个物种生态位重叠度普遍较高,当资源不足时,有竞争风险;优势树种的总体联结性表现为显著正联结,群落处于相对稳定的演替后期;χ²检验、联结系数和Pearson相关系数检验结果均显示,种间联结性的显著率极低,种间独立性较强;种间联结性与生态位重叠之间呈正相关。君子峰观光木群落较为成熟,资源利用充分,种间关系稳定,为促进观光木种群恢复和壮大,可适当限制与观光木生态位重叠度大、有显著负联结的种群规模,提高与之有正相互作用的物种比例,为观光木营造良好的生境。     

Responses of the distribution pattern of Quercus chenii to climate change following the Last Glacial Maximum

Aims Quercus chenii is a representative species of the flora in East China, with high ecological and economic values. Here, we aim to simulate the changes in the distribution pattern of this tree species following the Last Glacial Maximum (LGM) and to explore how climatic factors constrain the potential distribution, so as to provide scientific basis for protection and management of the germplasm resources in Q. chenii.
Methods Based on 55 presence point records and data on eight environmental variables, we simulated the potential distribution of Q. chenii during the Last Glacial Maximum, mid-Holocene, present and the year 2070 (the scenario of greenhouse gas emission is Representative Concentration Pathway 8.5) with MaxEnt model. The novel climate area and main factors influencing the changes in distribution pattern were evaluated by multivariate environmental similarity surface analysis and the most dissimilar variable analysis. The importance of environmental variables was evaluated by percent contribution, permutation importance and Jackknife test. Response curves were used to estimate the suitable value range of each variable.
Important findings The accuracy of MaxEnt model is very high, as indicated by the value of the area under the receiver operator characteristic curve of 0.9869 ± 0.0045. The highly suitable region for the present distribution covers southern Anhui, western Zhejiang, northeastern Jiangxi and eastern Hubei. The main factors affecting the potential distribution of Q. chenii are temperature and precipitation, with the former being more important. Mean temperature of the driest quarter is likely the main factor restricting Q. chenii growing in the north. During the LGM, the East China Sea Shelf occurs as the highly suitable region for the distribution of Q. chenii. In the mid-Holocene, the outline of the suitable area for the distribution of Q. chenii is similar to the present. The potential distribution region will likely move northward and experience an area expansion under the climate condition in 2070. At that time, climate anomaly will also be most severe compared to the LGM, mid-Holocene and present. Temperature seasonality and precipitation seasonality may be the main climatic factors promoting changes in the distribution pattern of Q. chenii.     

Spatial variability in species' potential distributions during the Last Glacial Maximum under different Global Circulation Models: Relevance in evolutionary biology

Ecological niche models (ENM) have been used to reconstruct potential distributions during the Last Glacial Maximum (LGM)—or other time periods—and this use is increasingly common in zoological studies. For this reason, we urgently need understanding factors affecting these predictions. Here, we examine how the use of different Global Circulation Models (GCMs) affects the variability in species' potential distributions during the LGM and how the degree of model extrapolation and its associated uncertainty depends on the GCM used. We develop these issues using two North American shrews, Notiosorex crawfordi and Cryptotis alticola, inhabiting two environmentally different regions. First, we compared paleoclimates in these two regions simulated by three GCMs: Community Climate System Model (CCSM), Model for Interdisciplinary Research on Climate (MIROC), and the Max‐Planck‐Institute für Meteorologie model (MPI). Then, we used maxent to estimate the LGM potential distribution of these two mammals under the three GCMs to assess the spatial variability and extrapolation uncertainty associated with idiosyncrasies of GCM. MIROC estimated noticeably more different climatic conditions than CCSM and MPI in the study areas during the LGM, and its pattern of environmental conditions was distributed differently. The MIROC scenario suggested a remarkable different prediction of potential distribution for both species, being more dramatic for the high mountain shrew, C. alticola. In particular, climatic differences among GCMs resulted in differences in the factors that limit and drive the potential distribution of the species during the LGM. Equally dramatic was the disagreement of extrapolation areas among GCMs. MIROC showed a greater number of pixels where extrapolation is required in both regions. Our findings should be taken into consideration when identifying areas of endemism, dynamic geographic barriers, and glacial refugia. When projecting into alternative scenarios of LGM climate, the idiosyncrasies of each GCM should be explicitly taken into account.     

Impact of climate change on suitable distribution range and spatial pattern in Amygdalus mongolica

为模拟、预测气候变化对孑遗、濒危植物蒙古扁桃(Amygdalus mongolica)潜在分布的影响, 利用最大熵(MAXENT)模型模拟、预测、对比、分析、揭示蒙古扁桃在最大冰期(CCSM及MIROC模型)、历史气候(1961-1990年)及未来气候(2020年、2050年和2080年, 政府间气候变化专门委员会排放情景特别报告的A2A情景)条件下的适宜分布范围和空间格局的变化。结果表明: (1)蒙古扁桃在历史气候条件下的潜在分布区集中在蒙古的南戈壁省及东戈壁省, 我国内蒙古巴彦淖尔市、阿拉善左旗、鄂尔多斯市、锡林郭勒盟西部, 河西走廊中部及东部, 宁夏北部及陕西北部, 以及河北北部的部分地区; (2)与历史气候条件下的潜在分布相比, 蒙古扁桃在最大冰期CCSM气候情景下的分布经历了明显的、大范围的向南迁移和范围缩小; (3)未来A2A气候情景下, 其潜在分布范围表现出在2020年明显扩大, 在2050年减小, 到2080年又略有增大的趋势。分布格局表现出不断向我国河北及内蒙古东部, 蒙古东部、北部及西部大幅度扩散、迁移的趋势。     

A Matrilineal Genetic Legacy from the Last Glacial Maximum Confers Susceptibility to Schizophrenia in Han Chinese

Mitochondrial dysfunction has been widely reported in schizophrenia patients. To dissect the matrilineal structure of Han Chinese with or without schizophrenia and to decipher the maternal influence and evolutionary history of schizophrenia, a total of 1212 schizophrenia patients and 1005 matched healthy controls, all of Han Chinese origin, were recruited in Hunan Province, China. We classified haplogroup for each individual based on mitochondrial DNA （mtDNA） sequence variations and compared the haplogroup distribution pattern between cases and controls. Haplogroup B5a presented a higher frequency in cases than in controls （P = 0.02, OR = 1.67, 95% CI = [1.09, 2.56]）, and this result could be confirmed by permutation analysis. Age estimation of haplogroup B5a in cases revealed a much younger age than that of controls, which was coincident with the Northern Hemisphere deglaciation at the end of the Last Glacial Maximum. Analysis of complete mtDNA in five patients belonging to haplogroup B5a showed that this background effect might be caused by haplogroup- defining variants m.8584G〉A and m.10398A〉G. Our results showed that matrilineal risk factor for schizophrenia had an ancient origin and might acquire a predisposing effect on schizophrenia due to the environment change and/or orchestration with other nuclear genetic factors appeared recently in human evolutionary history.     

Predictions of potential geographical distribution of Sinopodophyllum hexandrum under climate change

桃儿七(Sinopodophyllum hexandrum)为小檗科多年生草本植物, 是我国濒危传统藏药, 预测气候变化对该物种分布范围的影响对于其保护和资源可持续利用具有重要意义。该文利用获得的桃儿七136个地理分布记录和21个气候环境图层, 通过MaxEnt模型分析桃儿七在我国西部七省的潜在地理分布, 并基于该模型预测政府间气候变化专门委员会(IPCC)发布的SRES-A1B、SRES-A2和SRES-B1气候情景下21世纪20、50和80年代桃儿七分布范围。结果表明: 最热季平均温度、年降水量、温度季节性变动系数和等温性是影响桃儿七分布的主要气候因子; 在当前气候条件下, 桃儿七适宜的生境面积占研究区总面积的11.71%, 主要集中在青藏高原东缘的四川、甘肃、青海境内次生植被丰富、地形复杂的高海拔地区, 低适宜生境与不适宜生境分别占研究区总面积的15.86%与72.43%。由模型预测可知, 在SRES-A1B、SRES-A2和SRES-B1三种情景下, 桃儿七在研究区低适宜生境的数量相对变化较小, 在适宜生境先大幅减少后又缓慢增加。研究结果同时表明, 在未来气候变化条件下, 桃儿七的适宜生境平均海拔将逐渐升高, 范围以及几何重心极有可能先向北移, 然后再向西延伸至青藏高原内部较高海拔的山区。     

The role of glacial cycles in promoting genetic diversity in the Neotropics: the case of cloud forests during the Last Glacial Maximum

The increasing aridity during the Last Glacial Maximum (LGM) has been proposed as a major factor affecting Neotropical species. The character and intensity of this change, however, remains the subject of ongoing debate. This review proposes an approach to test contrasting paleoecological hypotheses by way of their expected demographic and genetic effects on Neotropical cloud forest species. We reviewed 48 paleoecological records encompassing the LGM in the Neotropics. The records show contrasting evidence regarding the changes in precipitation during this period. Some regions remained fairly moist and others had a significantly reduced precipitation. Many paleoecological records within the same region show apparently conflicting evidence on precipitation and forest stability. From these data, we propose and outline two demographic/genetic scenarios for cloud forests species based on opposite precipitation regimes: the dry refugia and the moist forests hypotheses. We searched for studies dealing with the population genetic structure of cloud forest and other montane taxa and compared their results with the proposed models. To date, the few available molecular studies show insufficient genetic evidence on the predominance of glacial aridity in the Neotropics. In order to disentangle the climatic history of the Neotropics, the present study calls for a general multi‐disciplinary approach to conduct future phylogeographic studies. Given the contradictory paleoecological information, population genetic data on Neotropical cloud forest species should be used to explicitly test the genetic consequences of competing paleoecological models.