Investment in visual system predicted by floral associations in sap beetles (Coleoptera: Nitidulidae)

Patterns in morphological variation are a central theme of evolution. Uncovering links between morphological character evolution and natural history, specifically feeding behaviour, is important to understanding biological diversity. Species within the sap beetles (Nitidulidae) exhibit a tremendous diversity of feeding behaviours. This immense diversity of feeding can be seen both between major lineages and very closely related taxa. Feeding behaviour diversity may drive morphological variation in several character systems (e.g., eyes). For example, in a shift from feeding on rotting fruit to flower-visiting (anthophily), selective pressures on the visual system may vary and ultimately lead to differences in eye morphology. We tested for potential morphological shifts in relative eye size among adult beetles. We specifically tested for significant relationships between relative eye size and the following factors flower-visiting and sex. We also tested for the influence of phylogeny on the evolution of relative eye size, implementing tests of trait correlation across a topology. We found greater relative eye size in taxa exhibiting anthophilous behaviour, regardless of phylogenetic relatedness or feeding behaviour of sister taxa. We were unable to recover a relationship between relative eye size and sex. Thus, feeding behaviour is currently the strongest predictor of eye size in sap beetles.     

Do cladistic and morphometric data capture common patterns of morphological disparity?

The distinctly non‐random diversity of organismal form manifests itself in discrete clusters of taxa that share a common body plan. As a result, analyses of disparity require a scalable comparative framework. The difficulties of applying geometric morphometrics to disparity analyses of groups with vastly divergent body plans are overcome partly by the use of cladistic characters. Character‐based disparity analyses have become increasingly popular, but it is not clear how they are affected by character coding strategies or revisions of primary homology statements. Indeed, whether cladistic and morphometric data capture similar patterns of morphological variation remains a moot point. To address this issue, we employ both cladistic and geometric morphometric data in an exploratory study of disparity focussing on caecilian amphibians. Our results show no impact on relative intertaxon distances when different coding strategies for cladistic characters were used or when revised concepts of homology were considered. In all instances, we found no statistically significant difference between pairwise Euclidean and Procrustes distances, although the strength of the correlation among distance matrices varied. This suggests that cladistic and geometric morphometric data appear to summarize morphological variation in comparable ways. Our results support the use of cladistic data for characterizing organismal disparity.     

Phenotypic traits meet patterns of resource use in the radiation of “sharpfin” sailfin silverside fish in Lake Matano

Disruptive natural selection on traits related to resource exploitation may lead to differential adaptation and finally to speciation. Trait utility, the performance of traits in terms of fitness, is a central criterion for the recognition of adaptive radiation. Utility of morphological structures involved in foraging can be detected by relating their variation to individual resource use. Here, we test for trophic adaptations in the radiation of “sharpfin” sailfin silversides (Atheriniformes: Telmatherinidae), endemic to ancient graben-lake Matano in central Sulawesi (Indonesia). This small species-flock is characterized by high phenotypic diversity, including traits most likely related to feeding ecology. Previous analyses suggest that species boundaries are porous, indicating very recent or possibly ongoing processes of species flock formation. To test for adaptation to resource use in this radiation, we compared morphological traits among trophic groups of individuals as identified by stomach content analyses. We analyzed variation in candidate structures or structural complexes commonly recognized as indicative of trophic adaptation in fish radiations, including shapes of body, oral and pharyngeal jaws, gill rakers and body size. We found fine-scaled morphological differentiation according to feeding habits, covering all traits analyzed. Fish-, shrimp- and egg-feeders were most distinct, with major axes of morphological variation fitting patterns of adaptation reported from other lacustrine fish radiations. Thus, the present results are consistent with fine-scaled morphological adaptation to resource use, supporting the adaptive character of the sharpfin sailfin silverside radiation.     

Early South Americans Cranial Morphological Variation and the Origin of American Biological Diversity

Recent South Americans have been described as presenting high regional cranial morphological diversity when compared to other regions of the world. This high diversity is in accordance with linguistic and some of the molecular data currently available for the continent, but the origin of this diversity has not been satisfactorily explained yet. Here we explore if this high morphological variation was already present among early groups in South America, in order to refine our knowledge about the timing and origins of the modern morphological diversity. Between-group (Fst estimates) and within-group variances (trace of within-group covariance matrix) of the only two early American population samples available to date (Lagoa Santa and Sabana de Bogotá) were estimated based on linear craniometric measurements and compared to modern human cranial series representing six regions of the world, including the Americas. The results show that early Americans present moderate within-group diversity, falling well within the range of modern human groups, despite representing almost three thousand years of human occupation. The between-group variance apportionment is very low between early Americans, but is high among recent South American groups, who show values similar to the ones observed on a global scale. Although limited to only two early South American series, these results suggest that the high morphological diversity of native South Americans was not present among the first human groups arriving in the continent and must have originated during the Middle Holocene, possibly due to the arrival of new morphological diversity coming from Asia during the Holocene.     

龙生型花生的遗传多样性

龙生型花生(Arachis hypogaea var.hirsute)是中国引进最早、种植最早的花生类型。经过不断地自然选择和人工选择,形成了许多各具特色的地方品种,并逐渐形成了次生中心。本实验对15份龙生型花生资源在植物学性状和品质性状及分子水平上进行了系统研究。结果表明:龙生型花生在植物学性状和品质性状上具有丰富的遗传多样性,在分子水平上差异也较大。变异系数在5.10-34.60之间,多样性指数在1.17-2.04之间,同时两者的变化趋势相反。基于植物学性状和品质性状上的聚类分析在阀值为6.5将龙生型花生分为两大类,一类主要包括广西的品种,另一类包括其它省份的品种;基于AFLP分析的聚类结果在阀值为0.39处分为5类,一类主要包括广西的品种,其它4类包括其它省份的品种。     

龙生型花生的遗传多样性

龙生型花生(Arachis hypogaea var.hirsute)是中国引进最早、种植最早的花生类型。经过不断地自然选择和人工选择,形成了许多各具特色的地方品种,并逐渐形成了次生中心。本实验对15份龙生型花生资源在植物学性状和品质性状及分子水平上进行了系统研究。结果表明:龙生型花生在植物学性状和品质性状上具有丰富的遗传多样性,在分子水平上差异也较大。变异系数在5.10~34.60之间,多样性指数在1.17~2.04之间,同时两者的变化趋势相反。基于植物学性状和品质性状上的聚类分析在阀值为6.5将龙生型花生分为两大类,一类主要包括广西的品种,另一类包括其它省份的品种;基于AFLP分析的聚类结果在阀值为0.39处分为5类,一类主要包括广西的品种,其它4类包括其它省份的品种。     

Ancestral State Reconstruction Reveals Rampant Homoplasy of Diagnostic Morphological Characters in Urticaceae,Conflicting with Current Classification Schemes

Urticaceae is a family with more than 2000 species, which contains remarkable morphological diversity. It has undergone many taxonomic reorganizations, and is currently the subject of further systematic studies. To gain more resolution in systematic studies and to better understand the general patterns of character evolution in Urticaceae, based on our previous phylogeny including 169 accessions comprising 122 species across 47 Urticaceae genera, we examined 19 diagnostic characters, and analysed these employing both maximum-parsimony and maximum-likelihood approaches. Our results revealed that 16 characters exhibited multiple state changes within the family, with ten exhibiting >eight changes and three exhibiting between 28 and 40. Morphological synapomorphies were identified for many clades, but the diagnostic value of these was often limited due to reversals within the clade and/or homoplasies elsewhere. Recognition of the four clades comprising the family at subfamily level can be supported by a small number carefully chosen defining traits for each. Several non-monophyletic genera appear to be defined only by characters that are plesiomorphic within their clades, and more detailed work would be valuable to find defining traits for monophyletic clades within these. Some character evolution may be attributed to adaptive evolution in Urticaceae due to shifts in habitat or vegetation type. This study demonstrated the value of using phylogeny to trace character evolution, and determine the relative importance of morphological traits for classification.     

Probing Diversity in the Plankton: Using Patterns in Tintinnids (Planktonic Marine Ciliates) to Identify Mechanisms

In diversity research, the use of survey data appears to have declined in favour of experimental or modeling approaches because direct relationships are difficult to demonstrate. Here we show that use of field data can yield information concerning the mechanisms governing diversity. First, we establish that tintinnids display a global latitudinal pattern of diversity similar to other pelagic organisms; species numbers appear to peak between 20° and 30° north or south. This common large scale spatial trend has been attributed to the gradient in water column structure across the global ocean. We then examine the generality of a relationship between planktonic diversity and water column structure by considering data from the Mediterranean Sea, in which water column structure changes seasonally. Among populations of foraminifera, tintinnids, and the dinoflagellates of the genus Ceratium, we compare data from trans-Mediterranean sampling conducted at different times and monthly changes in species richness at single sites. We find that water column structure alone appears to be a poor predictor of temporal changes in diversity. Lastly, we present an example of temporal changes in tintinnid diversity based on data from an oceanographic sampling station in the N. W. Mediterranean where resources, as chlorophyll, appear distinctly unrelated to changes in water column structure. We show that short-tem temporal changes in diversity (week to week shifts) can be related to changes in chlorophyll concentration. We conclude that in tintinnids diversity can be directly linked to characteristics of food resources.     

Computerized Analysis of Crustacean Relationships

The strengths and weaknesses of phylogenetic analysis using computers are reviewed from the viewpoint of understanding crustacean evolution. Computerized methods require the explicit presentation of characters and character state homologies. New techniques allow investigators to design evolutionary models into a character data matrix, or to use evolutionary models that make minimal a priori assumptions. The computer analysis relieves the investigator from the highly repetitious testing of trees, allows the concentration on the character state data, and provides objective methods for comparing trees, primarily their length. These are regarded as the strengths of computerized methods. The weaknesses of these methods include the relatively inscrutable nature of the character data matrix compared with the overall ‘gestalt’ of resulting trees, the difficulties of defining discrete homologies within the Crustacea, especially for counts of segmentation, the lack of clear intermediate character states in some multistate segmental characters, and the inability to define evolutionary polarity. These difficulties may be overcome by analysing the data using the minimal assumption models of character evolution, and by a recognition that the trees are a result of the input data, and therefore the data should be criticized, rather than the trees themselves. A ‘consensus’ character data set, including most extant major groups of the Crustacea as well as several key fossils, was assembled and revised by the participants in the workshop. An artificial taxon, ‘ur-crustacean characters’, was introduced to root the tree. Three observations may be made from parsimony analyses using several weighting and tree rooting methods. (1) The currently accepted large scale phylogeny and classification of the Crustacea is not corroborated. (2) The number of supposed plesiomorphic traits possessed by a taxon is not a good index for early derivation in crustacean evolution. (3) The taxon Maxillopoda is not supported by the arrangement of any of the trees.     

广西花坪SITE100样地甲虫标本照片数据集

通过在全球定点布设长期样地, 定量评估昆虫多样性与环境之间的关系具有重要意义。“SITE100”国际大科学计划在全球选定100个大样地, 每个样地统一选用罐诱法、马氏网法和飞行阻隔法三类采集装备, 从物种、形态和遗传多样性三个维度探究全球昆虫多样性格局。花坪被选为全球100个大样地之一。本文的数据集为花坪样地2020年生长季期间的鞘翅目收样结果, 历时7个月(2020.05.09-2020.11.23), 涵盖10个样点, 每个样点包括1套飞行阻隔器、1套马氏网和10个埋罐, 平均每周访问全部样点1次。研究期间共采集甲虫8,914头, 被划分为563个形态种, 涵盖57个科。数据集包括四部分, 第一部分为各样点每个采集装备每次收样所获得甲虫标本的集体照原图, 共计644张, 压缩后为照片1.zip; 第二部分为标注了形态种编号的甲虫标本的集体照, 共计644张, 压缩后为照片2.zip; 第三部分为甲虫标本数量统计数据, 涵盖2020年5月2日至2020年11月23日期间3种采集方式各日期采集甲虫的数量、采集样点的经纬度以及海拔信息, 共2个文件, 压缩后为数据1.zip; 第四部分为甲虫标本高级阶元(科级或亚科级)鉴定信息, 共计2个文件, 压缩后为数据2.zip。该数据集除了可以用于与其他SITE100样地结果进行联合分析之外, 还可用来比较不同栖境中甲虫的类群分布和形态差异, 部分类群的背面观图片为后续的几何形态学或者形态学研究提供数据支持。该数据集还是对花坪甲虫多样性的首次定量评估, 对于丰富我国生物多样性本底数据和了解我国南方昆虫区系的来源具有重要意义。     

Variation in freshwater fish assemblages along a regional elevation gradient in the northern Andes,Colombia

Studies on elevation diversity gradients have covered a large number of taxa and regions throughout the world; however, studies of freshwater fish are scarce and restricted to examining their changes along a specific gradient. These studies have reported a monotonic decrease in species richness with increasing elevation, but ignore the high taxonomic differentiation of each headwater assemblage that may generate high β‐diversity among them. Here, we analyzed how fish assemblages vary with elevation among regional elevation bands, and how these changes are related to four environmental clines and to changes in the distribution, habitat use, and the morphology of fish species. Using a standardized field sampling technique, we assessed three different diversity and two structural assemblage measures across six regional elevation bands located in the northern Andes (Colombia). Each species was assigned to a functional group based on its body shape, habitat use, morphological, and/or behavioral adaptations. Additionally, at each sampling site, we measured four environmental variables. Our analyses showed: (1) After a monotonic decrease in species richness, we detected an increase in richness in the upper part of the gradient; (2) diversity patterns vary depending on the diversity measure used; (3) diversity patterns can be attributed to changes in species distribution and in the richness and proportions of functional groups along the regional elevation gradient; and (4) diversity patterns and changes in functional groups are highly correlated with variations in environmental variables, which also vary with elevation. These results suggest a novel pattern of variation in species richness with elevation: Species richness increases at the headwaters of the northern Andes owing to the cumulative number of endemic species there. This highlights the need for large‐scale studies and has important implications for the aquatic conservation of the region.     

化学除草剂对农田生态系统野生植物多样性的影响

农田生物多样性是全球生物多样性的重要组成部分, 除草剂的大量施用对其产生了严重影响。本文综述了化学除草剂对农田生态系统中野生植物多样性的影响, 并分析归纳了其影响机制。除草剂的施用会使敏感植物减少, 抗药性植物增多, 从而改变农田生态系统中的野生植物物种组成, 并使其趋同化, 降低遗传多样性和物种多样性, 以致植物功能群单一化, 群落稳定性下降。除草剂的主要影响机制是杀死植物或改变其生长代谢、抗性、繁殖等, 改变生境, 并与人为因素、环境因素等产生协同影响。不同种类的除草剂影响程度不同, 且不同物种间、不同群落间的响应也存在差异。我国化学除草剂使用量持续增长, 应加强除草剂对野生植物多样性的影响及其机制研究, 重视除草剂使用历史记录和野生植物的长期监测, 以及除草剂使用规范和相关政策法律研究, 更好地保护我国农田生态系统中的生物多样性。     

Temporal lags in observed and dark diversity in the Anthropocene

Understanding biodiversity changes in the Anthropocene (e.g. due to climate and land‐use change) is an urgent ecological issue. This important task is challenging because global change effects and species responses are dependent on the spatial scales considered. Furthermore, responses are often not immediate. However, both scale and time delay issues can be tackled when, at each study site, we consider dynamics in both observed and dark diversity. Dark diversity includes those species in the region that can potentially establish and thrive in the local sites’ conditions but are currently locally absent. Effectively, dark diversity connects biodiversity at the study site to the regional scales and defines the site‐specific species pool (observed and dark diversity together). With dark diversity, it is possible to decompose species gains and losses into two space‐related components: one associated with local dynamics (species moving from observed to dark diversity and vice versa) and another related to gains and losses of site‐specific species pool (species moving to and from the pool after regional immigration, regional extinction or change in local ecological conditions). Extinction debt and immigration credit are useful to understand dynamics in observed diversity, but delays might happen in species pool changes as well. In this opinion piece we suggest that considering both observed and dark diversity and their temporal dynamics provides a deeper understanding of biodiversity changes. Considering both observed and dark diversity creates opportunities to improve conservation by allowing to identify species that are likely to go regionally extinct as well as foreseeing which of the species that newly arrive to the region are more likely to colonize local sites. Finally, by considering temporal lags and species gains and losses in observed and dark diversity, we combine phenomena at both spatial and temporal scales, providing a novel tool to examine biodiversity change in the Anthropocene.     

Low functional redundancy in coastal marine assemblages

The relationship between species and functional diversity remains poorly understood for nearly all ecosystem types, yet determining this relationship is critically important for developing both a mechanistic understanding of community assembly and appropriate expectations and approaches to protecting and restoring biological communities. Here we use two distinct data sets, one from kelp forests in the Channel Islands, California, and one from a global synthesis of marine reserves, to directly test how variation in species diversity translates into changes in functional diversity. We find strong positive relationships between species and functional diversity, and increased functional diversity of fish assemblages coinciding with recovery of species diversity in marine reserves, independent of the method used for classifying species in functional groups. These results indicate that low levels of redundancy in functional species traits exist across a suite of marine systems, and that fishing tends to remove whole functional groups from coastal marine ecosystems.     

Cladistic analysis of molecular and morphological data

Considerable progress has been made recently in phylogenetic reconstruction in a number of groups of organisms. This progress coincides with two major advances in systematics: new sources have been found for potentially informative characters (i. e., molecular data) and (more importantly) new approaches have been developed for extracting historical information from old or new characters (i. e., Hennigian phylogenetic systematics or cladistics). The basic assumptions of cladistics (the existence and splitting of lineages marked by discrete, heritable, and independent characters, transformation of which occurs at a rate slower than divergence of lineages) are discussed and defended. Molecular characters are potentially greater in quantity than (and usually independent of) more traditional morphological characters, yet their great simplicity (i. e., fewer potential character states; problems with determining homology), and difficulty of sufficient sampling (particularly from fossils) can lead to special difficulties. Expectations of the phylogenetic behavior of different types of data are investigated from a theoretical standpoint, based primarily on variation in the central parameter λ (branch length in terms of expected number of character changes per segment of a tree), which also leads to possibilities for character and character state weighting. Also considered are prospects for representing diverse yet clearly monophyletic clades in larger-scale cladistic analyses, e. g., the exemplar method vs. “compartmentalization” (a new approach involving substituting an inferred “archetype” for a large clade accepted as monophyletic based on previous analyses). It is concluded that parsimony is to be preferred for synthetic, “total evidence” analyses because it appears to be a robust method, is applicable to all types of data, and has an explicit and interpretable evolutionary basis. © 1994 Wiley-Liss, Inc.     

A new method to estimate aquatic invertebrate diversity in French shallow lakes and ponds

Shallow lakes and ponds are valuable ecosystems for conservation management. Aquatic invertebrates constitute a large proportion of diversity in these ecosystems, but their assessment is potentially time consuming and requires great expertise. The use of indicator taxa to estimate invertebrate diversity may resolve part of these difficulties. These indicators are rarely identified or their reliability is uncertain, i.e. they are based on partial inventories, neglecting groups with high diversity. In this study, invertebrate richness was assessed from 46 sites in France in various altitudinal, climatic, geological, human-impacted, and hydro-morphological contexts. Invertebrate identification was performed as accurately as possible in all taxonomic groups. Several potential indicators of diversity based on five key criteria were tested: strong direct correlation, identification facilities, strong cross-taxon congruence, low complementarity of the sampled habitats, and ubiquity for selected indicators. Three approaches were proposed to define these indicator groups: (1) a single taxonomic group as indicator, (2) a combination of targeted groups, and (3) a holistic inventory at low taxonomic resolution as a classical rapid assessment method for freshwater ecosystems. Results show that it is not recommended to use only one indicator group. The choice of several targeted groups could be a good intermediate solution but is not without bias. The rapid assessment inventory proposed is the most valuable method, and allows the estimation of invertebrate richness with a quasi-perfect correlation.     

丛枝菌根真菌最新分类系统与物种多样性研究概况

丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)是自然界分布最广泛的一类植物共生真菌,能够与大部分高等植物的根系形成共生关系.由于它们在农林、环境等领域的巨大应用潜力,国内外关于AMF物种多样性的研究一直受到较高的关注.然而,AMF专性共生的特征以及研究方法不够理想等因素长期阻碍了AMF物种多样性的研究进展.近年来,研究方法的改进与新技术的应用为AMF物种多样性的研究提供了极好的机遇.简述了AMF的最新分类系统及全球物种数量、AMF物种多样性影响因素以及AMF物种多样性研究方法三个方面的研究进展,并分析了今后在AMF物种多样性相关领域值得关注的研究方向.     

Congruence between morphological and molecular markers inferred from the analysis of the intra-morphotype genetic diversity and the spatial structure of Oxalis tuberosa Mol.

Oxalis tuberosa is an important crop cultivated in the highest Andean zones. A germplasm collection is maintained ex situ by CIP, which has developed a morphological markers system to classify the accessions into morphotypes, i.e. groups of morphologically identical accessions. However, their genetic uniformity is currently unknown. The ISSR technique was used in two experiments to determine the relationships between both morphological and molecular markers systems. The intra-morphotype genetic diversity, the spatial structures of the diversity and the congruence between both markers systems were determined. In the first experience, 44 accessions representing five morphotypes, clearly distinct from each other, were analyzed. At the molecular level, the accessions exactly clustered according to their morphotypes. However, a genetic variability was observed inside each morphotype. In the second experiment, 34 accessions gradually differing from each other on morphological base were analyzed. The morphological clustering showed no geographical structure. On the opposite, the molecular analysis showed that the genetic structure was slightly related to the collection site. The correlation between both markers systems was weak but significant. The lack of perfect congruence between morphological and molecular data suggests that the morphological system may be useful for the morphotypes management but is not appropriate to study the genetic structure of the oca. The spatial structure of the genetic diversity can be related to the evolution of the species and the discordance between the morphological and molecular structures may result from similar selection pressures at different places leading to similar forms with a different genetic background.