秦岭国家植物园蝴蝶群落结构与多样性

为了查明秦岭国家植物园蝴蝶资源和多样性状况, 本研究选取了5种生境, 利用样线法进行了3年的蝴蝶多样性观测。结果表明: 秦岭国家植物园蝴蝶共有5科76属134种; 物种丰富度指数、物种多样性指数、均匀度指数和优势度指数分别为1.3295、3.4616、0.7068和0.7656; 其中蛱蝶科属数及物种数最多(33属65种), 凤蝶科最低(5属10种); 蛱蝶科物种多样性指数及物种丰富度指数最高, 分别为2.8525及1.3622; 凤蝶科多样性指数最低(1.4936); 粉蝶科物种丰富度指数最低(0.2790)。5种生境中, 随着植被丰富度的增加, 蝴蝶多样性指数上升。     

Species richness of gall-forming insects in a tropical rain forest: correlations with plant diversity and soil fertility

We tested two hypotheses to explain changes in species richness ofgall-forming insects. The first hypothesis proposes that gall-forming insectspecies richness increases as more potential host–plant species areavailable. The second hypothesis implies that soil fertility affects plantcolonization by gall-forming insects. Seven sites, representing strongdifferences in vegetation and soil were chosen at the Lacandona tropical rainforest region, Chiapas, Mexico. Overall, we found 1522 individual plantsbelonging to 340 different plant species. From this, we found gall-forminginsects on 737 (43.9%) plants and on 74 (22%) of total plant species. We found asignificant negative correlation between gall-forming insect species richnessand species richness of plants, which does not support the hypothesis that plantspecies richness is an important factor in generating the radiation ofgall-forming insects. Using phosphorus as an indicator of soil fertility, wefound the lowest number of plants with gall-forming insects and the smallestgall-forming insect load per individual plant in the more fertile soil(alluvial). In contrast, the highest number of plants with galls and the highestgall-forming insect load per plant were found at a savanna-like vegetationsite, where the poorest soil was recorded. These results did not support thesoil fertility hypothesis in terms of species richness, but did with respect toabundance of plants with galls.     

阿尔泰山小东沟林区乔木物种丰富度空间分布规律

对一定区域内生物多样性的合理保护往往需要在景观水平上了解生物多样性分布的总体规律.借助于典型抽样调查和遥感及地理信息系统相结合的方法来预测物种丰富度是定量研究生物多样性宏观分布规律的重要途径.以阿尔泰山小东沟林区为对象,在外业调查的基础上,选取主要气象因子、地形因子和植被指数(NDVI)作为预测变量,利用主成分分析和多元回归分析分别提取主要环境信息和构建物种丰富度预测模型,借助ArcGIS9.1的空间分析功能,得到了阿尔泰山小东沟林区乔木物种丰富度空间分布预测图,并利用残差图评价其精度.将小东沟乔木物种丰富度预测图分别与坡度、坡向和海拔图叠加,分析不同地形条件下乔木物种丰富度的空间分布规律.结果表明:占总研究区面积70.28％的区域,其乔木物种丰富度在3到4种之间.坡度0-5°的地形条件下乔木物种丰富度出现频率最高的数值是3,其余坡度条件下,乔木物种丰富度出现频率最高的数值是4;乔木物种丰富度在西坡和西北坡出现频率最高的数值是3,其余坡向乔木物种丰富度出现频率最高的数值均是4;海拔梯度上,乔木物种丰富度出现频率最高的数值呈现先增加后减少的趋势.残差类型面积统计表明,较强预测水平面积和中等预测水平面积占研究区总面积的94.62％,表明预测效果较好.     

大别山、仙居县和溧水区大型真菌多样性

大型真菌具有重要的经济价值和生态意义,是生态系统不可缺少的重要组成部分。本研究于2018年7月-10月和2019年7月-10月采用踏查法对大别山鹞落坪自然保护区和天堂寨自然保护区、仙居县和溧水区的大型真菌多样性进行调查,共采集到600多份样本,结合形态特征和分子进行物种鉴定,参考大型真菌书籍进行鉴定。结果表明：大别山研究区共鉴定得到大型真菌84种,隶属5纲11目27科56属;仙居县研究区大型真菌共计87种,隶属6纲10目25科56属;溧水研究区大型真菌79种,隶属5纲10目22科38属。多孔菌科（Polyporaceae）和口蘑科（Tricholomataceae）是三个研究区的共有优势科。α-多样性指数分析得出,在不同的生境下,多样性是溧水研究区>仙居县研究区>大别山研究区。研究结果表明,大型真菌物种的丰度与海拔和纬度呈负相关,三个研究区的大型真菌物种不仅有一些北温带特征,也有一些泛热带成分,世界分布属和北温带分布属占当地属总数的大部分。     

Many broadly-shared mycobionts characterize mycorrhizal interactions of two coexisting epiphytic orchids in a high elevation tropical forest

Interspecific interactions play an important role in community assembly. A basic ecological question is whether interactions are specialized (one to one) or generalized (many to many). Specialization of interactions should ideally be assessed across several populations because species could be specialists at a particular site but generalists when several sites are considered. Mycorrhizal interactions are fundamental for orchid life and distribution, but their level of specialization is still under debate. To understand the extent to which epiphytic orchids are specialists in their mycorrhizal interactions, we studied the richness and phylogenetic structure of mycobionts across different sites, and the similarity in the mycobiont composition between coexisting orchid species. We sequenced the nrDNA ITS2 region and explored the mycobiont communities associated with two epiphytic orchids, Epidendrum marsupiale and Cyrtochilum pardinum, at two elevations within two sites in Ecuador. We found 108 OTUs belonging to Serendipitaceae (66), Ceratobasidiaceae (22), Atractiellales (11) and Tulasnellaceae (9). Orchids at the highest elevations hosted the highest OTU richness. The two orchid species shared a high percentage of mycobionts between all sites. No phylogenetic structure within orchid mycorrhizal communities was found at any sites or elevations. Our results indicate that the studied orchids are generalists and share a broad group of mycobionts (16 OTUs) with no apparent niche segregation within or between sites.     

长江三峡库区昆虫丰富度的海拔梯度格局——气候、土地覆盖及采样效应的影响

为了探讨长江三峡库区昆虫丰富度的海拔分布格局以及关键影响因子,针对库区记录的3517种昆虫及其中的害虫,我们整理了这些物种的海拔分布范围数据,分析不同分类学水平、种域宽度等级和分类群的物种丰富度海拔分布模式,采用回归树方法探讨主导的影响因素,并检验相关的假说。结果显示:1)在科、属、种水平,三峡库区分布的昆虫和害虫丰富度均呈随海拔上升先增而后减的格局;狭域、中域和广域种具有显著不同的格局,但三个种域等级的昆虫物种丰富度在海拔1400m以上均显著下降,而害虫丰富度在海拔1200m以上即显著下降。2)对记录昆虫种数>20的科进行TWINSPAN分类,得到物种丰富度海拔格局的4种主要模式;尽管不同程度受采样效应的影响,4种模式均属于单峰格局;3)库区土地利用类型的海拔变化对昆虫、害虫物种丰富度海拔分布具有首要和直接的影响;水热平衡或初级生产力是影响昆虫海拔格局的主导气候因子;而1月均温=0℃可能是限制大多数昆虫物种分布上限的临界温度。上述结果表明,三峡库区的昆虫物种丰富度及其不同组分均具有典型的单峰分布格局,这种格局是人类活动与气候梯度综合作用的结果,但前者的作用更为直接,主要体现在土地利用的海拔梯度变化。这些认识对昆虫多样性资源管理和农林业害虫防治具有参考意义。     

Geographic patterns and environmental correlates of taxonomic and phylogenetic diversity of aquatic plants in China

Studies on large-scale geographic patterns of aquatic plant diversity can promote research on the generality of macroecological patterns in different ecosystems. Here, we compiled a checklist of 889 aquatic angiosperms in China, including 738 helophytes (emergent and marshy plants) and 151 hydrophytes (submerged, free-floating, and floating-leaved plants). We explore the geographic patterns and environmental correlates of aquatic plant diversity based on six metrics including species richness (SR), weighted endemism (WE), phylogenetic diversity (PD), phylogenetic endemism (PE), the standardized effect size of phylogenetic diversity (PDses), and the standardized effect size of mean phylogenetic distance (MPDses). Our results show that the diversity of aquatic plants in China is extremely uneven, with high diversity in southeastern China and low diversity in northwestern China, and the geographic patterns of taxonomic and PD are generally consistent. The pattern of helophytes differs from that of hydrophytes. Notably, the wavy-shaped pattern of aquatic plant diversity (especially SR and PD for hydrophytes) across the latitude observed in this study is not consistent with those previously observed for aquatic plants in other continents. Climatic variables and water environmental variables are the main drivers of aquatic plant diversity in China; however, the effects of individual variables differ between helophytes and hydrophytes. Water environmental variables have a greater impact on PDses and MPDses of hydrophytes than those of helophytes. Overall, our work provides insight into understanding the large-scale patterns of aquatic plant diversity and is a critical addition to previous studies on the macroecological pattern of terrestrial organisms.     

Biodiversity and multifunctionality in a microbial community: a novel theoretical approach to quantify functional redundancy

Ecosystems have a limited buffering capacity of multiple ecosystem functions against biodiversity loss (i.e. low multifunctional redundancy). We developed a novel theoretical approach to evaluate multifunctional redundancy in a microbial community using the microbial genome database (MBGD) for comparative analysis. In order to fully implement functional information, we defined orthologue richness in a community, each of which is a functionally conservative evolutionary unit in genomes, as an index of community multifunctionality (MF). We constructed a graph of expected orthologue richness in a community (MF) as a function of species richness (SR), fit the power function to SR (i.e. MF = cSR^a), and interpreted the higher exponent a as the lower multifunctional redundancy. Through a microcosm experiment, we confirmed that MF defined by orthologue richness could predict the actual multiple functions. We simulated random and non-random community assemblages using full genomic data of 478 prokaryotic species in the MBGD, and determined that the exponent in microbial communities ranged from 0.55 to 0.75. This exponent range provided a quantitative estimate that a 6.6–8.9% loss limit in SR occurred in a microbial community for an MF reduction no greater than 5%, suggesting a non-negligible initial loss effect of microbial diversity on MF.     

Altitudinal distribution of native and alien plant species in roadside communities from central Argentina

Roadsides may homogenize the distribution of native species and act as corridors for the spread of alien taxa. We examined the variation in native and alien plant species richness and composition at two spatial scales defined by altitude and habitat type (edges and fill slopes), as well as the relationship between native and exotic species richness in roadside plant communities in mountains from central Argentina. Following a gradient from 1100 to 2200 m a.s.l. along a mountain road, plant species cover was recorded within sample plots of 30 m × 10 m systematically located at 100‐m altitude intervals on both roadside habitats. Although native species richness decreased with altitude and composition changed accordingly, the number of alien species peaked at both extremes of the elevation gradient and did not reflect an altitudinal replacement of chorological groups. The number of both native and alien species was higher in roadside edges, but a negative association between the richness of native and alien species occurred only on fill slopes, suggesting that roadside habitats differ in their susceptibility to plant species colonization and in the mechanisms driving native and alien species richness. Our results highlight the importance of altitude and roadside habitat as factors controlling plant species richness and composition along roadside communities in central Argentina. Although altitude acts as a filter for native plants, it apparently did not constrain the establishment of alien species along the studied roadsides, indicating that the influence of this road as a plant species corridor may increase with time, promoting the opportunities for aliens to expand their current distribution.