Jeremy A. Miller; Joshua H. Miller; Dinh-Sac Pham; Kevin K. Beentjes

“ Yet, names are the mechanism by which data about a species (including geographic distribution) are aggregated. The process of naming and describing species, however, is time-consuming. While online innovations are increasing the pace of species descriptions and improving accessibility to taxonomic data, these advances come at a time when investment and training in taxonomy is declining [10] , [11] . If the fine-grained pattern of arthropod biodiversity is to be broadly integrated into conservation assessment, it is apparent that we need to diminish dependence on formal scientific names. ”

“ In an era of biodiversity crisis, climate change, and other challenges, the scientific and public spheres have common interest in synergies that make research products more responsive to the questions of the day. Thus, practices that make it easier to compare and combine data across different inventory studies are highly desirable for deriving the maximum information value from our research investment. ”

“ Studies with a high proportion of identified species (which are largely found in temperate regions) are relatively easy to evaluate for community similarity, while studies in regions with more poorly developed taxonomy (e.g., the tropics) may not be as easily reconciled. This roadblock can be bypassed using the cyberdiversity framework, which allows data on the whole community to be made publically available, and can foster reconciliation of independent inventories, including those with high proportions of undescribed species. ”

“ Spiders are one of the richest orders of life on earth, and structured inventories (i.e., surveys that use replicable sampling protocols with multiple complimentary collecting methods) are fundamental sources of data about species richness [28] – [29] . However, inventories in temperate regions have significantly higher proportions of their species identified with scientific names than inventories in tropical regions (Fig. 1) . This is perhaps not surprising given the relatively low number of species and high intensity of taxonomic research at temperate latitudes. ”

“ The proportion of shared species is a useful and intuitive concept for comparing two communities. When inventories are nearly complete, the Jaccard index expresses this adequately. But when sampling is incomplete, especially in communities of megadiverse taxa with large proportions of rare species, the Jaccard can underestimate the proportion of shared species [65] – [66] . Shared rare species present the most significant challenge because they are most likely to be missed in one or both inventories. ”

“ This asymmetry arises largely because the geographic ranges and environmental tolerances of individual arthropod species tend to be more restricted than vertebrates or vascular plants, enabling megadiverse arthropod groups to track ecological gradients at finer spatial resolution. Because of their high richness and sensitivity to environmental variables, arthropods offer some of the finest-grained data with which to assess terrestrial biodiversity at individual localities (alpha [α] diversity) and changes across landscapes (beta [β] diversity) [5] , [8] . ”

“ However, one of the greatest impediments to the broader use of arthropod communities for studying and maintaining global biodiversity is our current profoundly incomplete and geographically biased data on fundamental taxonomy. ”

“ Thus, the relative abundances of species sampled in this way are not expected to be representative of their actual abundances within communities [71] ; random sampling of individuals from ecologically and morphologically diverse species communities in structurally complex habitats is usually not realistic. While species rarity is useful in the context of non-parametric species richness and shared species estimators, diversity measures that rely on community species abundance distributions (e.g., Chao's abundance-based Jaccard index) may be problematic in this context. ”

“ Such studies typically organize their data using morphospecies codes, which make it difficult for data from independent inventories to be compared and combined. To combat this shortcoming, we offer cyberdiversity, an online community-based approach for reconciling results of independent inventory studies where current taxonomic knowledge is incomplete. Participating scientists can upload images and DNA barcode sequences to dedicated databases and submit occurrence data and links to a web site (www.digitalSpiders.org) . ”

“ With broader adoption of the cyberdiversity approach, networks of information-sharing taxonomists can more efficiently and effectively address taxonomic impediments while elucidating landscape scale patterns of biodiversity. ”

“ Species sorting based on integrated analysis of DNA and morphology (IOTUs) found fewer species than the algorithmic approach [53] based on sequence data alone. Based on IOTU designations and barcode sequences, minimum genetic distances between species were almost always larger than distances within species (Figs. 4B and S1B, D in S1 File) . The incongruence between DNA-only (BIN) and the integrated approach (IOTU) is almost certainly attributable to the many rare species that characterize our inventories ”

“ Cyberdiversity is an online approach to facilitate species recognition regardless of taxonomic determination status. Web-based tools may include collections of digital images, DNA sequences, or ideally both. The cyberdiversity approach engages several recognized impediments to the understanding of fundamental aspects of megadiversity and the wider adoption of arthropod data for conservation assessment. ”

“ All records can be viewed through Google Earth with markers linked to collections of images on Morphbank. Records may be associated with a DNA barcode sequence and linked to the BOLD database. Each IOTU is associated with a collection of one or more images, linked to a corresponding image or image collection on Morphbank. Where an IOTU is associated with a valid taxonomic name, this determination is credited to one or more taxonomists along with their contact information. Ours is the first structured tropical spider inventory study to include DNA barcode data for most of the sampled community. ”

“ Species richness and inventory completeness were assessed using non-parametric estimators. Community similarity was evaluated using a novel index based on the Jaccard replacing observed with estimated values to correct for unobserved species. We use a distance-decay framework to demonstrate a rudimentary model of landscape-scale changes in community composition that will become increasingly informative as additional inventories participate. ”

“ Whether the β-diversity patterns of spiders and other megadiverse arthropods accord or contrast with other communities of organisms, increased availability and analysis of data based on diverse taxa with fine-grained climatic and spatial structuring will contribute to a richer understanding of these fundamental biological questions. ”

“ The number of species observed from each inventory, and the number of singletons, unique, doubletons, and duplicates in each inventory are given, as well as four non-parametric estimators of sample completeness: Chao 1, ACE, Chao 2, and ICE (upper 95% confidence intervals provided for Chao 1 and Chao 2) . Estimated Inventory completeness is variable, but none are complete. Hence, assessment of community similarity based on these inventories should account for unobserved shared species. Table 1 "Observed and estimated species richness for the three rapid inventories of spiders in Vietnam. ”

“ A healthy ethic of data sharing can advance research across the community. We ask authors to think carefully about the benefits they derive from shared data and acknowledge accordingly those responsible if they hope to foster this incipient trend.
Sampling strategy and assessment
During structured inventory surveys, a selection of semi-quantitative field sampling methods is typically applied to estimate spider species richness [28] , [30] , [35] – [37] . ”

“ WIN: extraction of arthropods from sifted leaf litter using Winkler traps. Methods conducted during daylight hours are unfilled, methods conducted during night hours are black-filled. Methods targeting above-ground strata are up-pointing triangles, methods targeting ground strata are down-pointing triangles or a circle (WIN) . Each WIN sample required two field hours; samples using all other samples were one hour each. High reversed Cobra scores indicate maximum efficiency of a method for contributing species to the inventory; low scores indicate sampling saturation for that method. ”

“ All data shown on digitalSpiders are protected by a creative commons license, meaning they can be used for third party research provided the original source is cited and derivative works are distributed according to a similar license. ”

“ This inventory was conducted in October, the same time of year as our Vietnamese study, by an independent research team. The results of the Doi Inthanon study have not been published in the form of a scientific journal article. Nevertheless, because the leaders of this study chose to post images of their morphospecies online, we were able to rapidly assess characteristics of change in spider communities (β-diversity) across ca. 1,000 km. ”

“ Distance decay of community similarity.Pair-wise community similarity for Southeast Asian spider communities and their decay against (A) geographic and (B) climatic distances. Similarity is significantly correlated with both geographic and climatic distances (mantel tests; p<0.05) . For geographic distance, the estimated community halving distance is 171 km. With additional inventory sites, variance partitioning could be used to disentangle covariance between geographic and climatic change. Cobra analysis (see Methods, Table 3) revealed both strengths and inefficiencies in our sampling regime. ”

“ Fortunately, it is not the first study from the region to make libraries of morphospecies images available online. Images of all morphospecies resulting from a 2003 survey of spiders from Doi Inthanon National Park, Chang Mai Province, Thailand have also been posted online (http://aracnologia.macn.gov.ar/ThaiPlot/) . ”

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