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DNA sequences offer powerful tools for describing the members and interactions of natural communities. In this study, we establish the to-date most comprehensive library of DNA barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland. To demonstrate its utility, we apply the library to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers. Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time and describe the abundance and phenology of species in the rapidly changing arctic environment. Overall, 403 terrestrial animal and 160 vascular plant species were recorded by morphology-based techniques. DNA barcodes ( CO1) offered high resolution in discriminating among the local animal taxa, with 92% of morphologically distinguishable taxa assigned to unique Barcode Index Numbers ( BINs) and 93% to monophyletic clusters. For vascular plants, resolution was lower, with 54% of species forming monophyletic clusters based on barcode regions rbcL a and ITS2. Malaise catches revealed 122 BINs not detected by previous sampling and DNA barcoding. The insect community was dominated by a few highly abundant taxa. Even closely related taxa differed in phenology, emphasizing the need for species-level resolution when describing ongoing shifts in arctic communities and ecosystems. The DNA barcode library now established for Zackenberg offers new scope for such explorations, and for the detailed dissection of interspecific interactions throughout the community. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim To evaluate the effect of post-glacial migration lags on the current distribution of Alpine plants and the factors responsible for possible range-filling differences among species. Location Austrian Alps. Methods We used species distribution models to predict environmentally suitable sites for 183 Alpine plants at a fine spatial resolution (100 × 100 m2). We overlaid these predictions with independent mapping data (3′× 5′) and calculated the extent to which species fill their potential ranges at this coarser grain based on several different approaches. Moreover, we correlated range-filling estimates with the magnitude of improvement of distribution models when using the distance to putative glacial refugia as an additional independent variable. Finally, we compared species-specific range-filling estimates with traits related to dispersal capacity and competitive ability of these species as well as with characteristics of their habitats. Results Even under a conservative approach, incomplete range filling appears common, with 46% and 31% of the species studied occurring in less than 75% and 50% of their predicted suitable ranges, respectively. Proximity to glacial refugia generally accounts for a lower percentage of the deviance in species distribution data (0-20%, mean 4%) than environmental variables (9-57%, mean 27%). However, its importance correlates closely and negatively with the calculated range-filling estimates. Range filling significantly increases with the dispersal capacity of a species' propagules and the breadth of its altitudinal niche. Calcicolous species have lower range filling than silicicolous plants and substrate generalists. Conclusions Our results suggest that the current ranges of many Alpine plants are still shaped by delayed Holocene recolonization of suitable sites. Hence, long-term migration lags also affect plant distribution in mountainous areas, at least on regional scales. These findings question whether high mountain floras will be able to track the expected rapid, climate change driven shifts in habitat. [ABSTRACT FROM AUTHOR]