Poa, the largest genus of grasses (Poaceae) with over 500 species, occurs throughout temperate and boreal regions in both hemispheres. A phylogenetic study of Poa based on trnT-trnF chloroplast DNA sequence data is presented focusing on basal relationships, major clades, generic boundaries, and placement of putatively closely related genera. Results support the monophyly of the main lineage of Poa if subgen. Andinae is excluded and Anthochloa, Austrofestuca, Dissanthelium (at least in part), and Eremopoa are included. The main Poa clade and subgen. Andinae resolve within a strongly supported Poinae-Alopecurinae-Miliinae clade (PAM). The subdivision of Poa into five major clades, proposed based on chloroplast restriction site data, is supported by sequence data. The basal-most clade (ArcSyl) comprises Poa subgen. Arctopoa and subgen. Poa sect. Sylvestres, two groups having disparate morphology, but similar cpDNA. The next-diverging clade (BAPO), comprising sects. Bolbophorum, Alpinae, Parodiochloa, and Ochlopoa, is strongly supported and characterized by highly divergent cpDNA. The majority of Poa species and sections form a strongly supported clade comprising major clades SPOSTA, PoM, and HAMBADD. Newly reported in this study is Eremopoa as a distinct lineage positioned between this higher Poa clade and BAPO. A revised infrageneric classification of Poa comprising five subgenera is proposed. Two new subgeneric divisions of Poa are proposed: subgen. Stenopoa for the SPOSTA clade and supersect. Homalopoa for the HAMBADD clade. The monotypic genus Anthochloa is reduced to Poa sect. Anthochloa, and its one species recognized as Poa lepidula.

Ten years after DNA barcoding was initially suggested as a tool to identify species, millions of barcode sequences from more than 1100 species are available in public databases. While several studies have reviewed the methods and potential applications of DNA barcoding, most have focused on species identification and discovery, and relatively few have addressed applications of DNA barcoding data to ecology. These data, and the associated information on the evolutionary histories of taxa that they can provide, offer great opportunities for ecologists to investigate questions that were previously difficult or impossible to address. We present an overview of potential uses of DNA barcoding relevant in the age of ecoinformatics, including applications in community ecology, species invasion, macroevolution, trait evolution, food webs and trophic interactions, metacommunities, and spatial ecology. We also outline some of the challenges and potential advances in DNA barcoding that lie ahead.

The perceptual features people extract from objects depend on how they typically categorize them. It is now commonly acknowledged that the human perceiver can interact with the objects of his or her world at different, hierarchically organized levels of categorization. People who have learned to categorize an object as general or specific may therefore perceive different features in this object. We report two experiments that examined the hypothesis that the nature of categorization (general vs. specific) can influence the perceived properties of an identical distal object.Even casual observers would have little difficulty recognizing Figure 1 as an office scene. They would notice the typical arrangement of a chair, a desk, a computer, a coffee mug, and other objects found in an office environment. Even if an observer never saw these particular objects before, he or she should nevertheless recognize them effortlessly at a general level as a chair, desk, computer, and mug, and maybe even at a more specific level as a desk chair, Art Deco desk, Apple Macintosh, and coffee mug.The research we report here bridges the gap between object perception and object categorization. We examined the hypothesis that the perceptual features that people extract from objects depend on how they typically categorize them. For example, the seminal research of Rosch, Mervis, Gray, Johnson, and Boyes-Braem (1976) revealed that the human perceiver commonly categorizes the objects of his or her world at general and more specific levels (e.g., as car vs. Ford; bird vs. robin; dog vs. Labrador retriever). People who have learned to categorize an object at a specific level could therefore extract and perceive different features from people who categorize the same object at a general level.The idea that people do not always perceive all the features of distal objects has recently come under closer scrutiny in the changedetection literature (see Simons & Levin, 1997, for a review). In a typical experiment (see Rensink, O'Regan, & Clark, 1997), one feature in a scene changes between successive presentations separated by a blank. For example, an object can disappear or change location or color. The common finding is that people do not detect such a straightforward change immediately, even though they know there has been a change. This suggests that features that are irrelevant for encoding an object (Friedman, 1979) or a scene (Rensink et al., 1997) will tend to go unnoticed (Simons & Levin, 1997; see also Dennett, 1991;Hochberg, 1982). As O'Regan (1992) elegantly put it, "'Seeing' does not involve simultaneously perceiving all the features present in an object, but only a very small number, just sufficient to accomplish the task at hand" (p. 482).We report two change-detection experiments which tested the hypothesis that people perceive the features of an object differently if they have learned to categorize it differently-that is, at different levels of specificity. We then examine the implications of our results for theories of object categor...

In many studied plants, typical responses to cold treatment include up-regulating the hydrophilic COR/LEA genes and down-regulating photosynthesis-related genes, carbohydrate metabolism, GDSL-motif lipase, hormone metabolism and oxidative regulation genes. However, next to nothing is known about gene expression in arctic plants, which are actually adapted to a harsh, cold environment. The molecular mechanisms behind the many specific adaptations of arctic plants, such as slow growth, well-developed root systems and short stature, are not well understood. In this study, we examine whole plantlet transcriptome differences between two arctic and two temperate Oxytropis (Fabaceae) species, grown under their respective controlled environmental conditions. Gene expression differences are analyzed using cDNA library subtraction followed by expressed sequence tags sequencing and annotation. Sequences from a total of nearly 2,000 clones cluster into 121 and 368 unique genes from the arctic and from the temperate plants, respectively. The predominant biological process for genes from the arctic-enriched library is “response to stimulus”. A concurrent overexpression of pathogenesis-related class 10 proteins (PR-10), plant defensin and cold dehydrin genes is a novel feature for species adapted to stressful growth environment. The temperate-enriched genes are involved in photosynthesis, translation and nucleosome assembly. Interestingly, both arctic and temperate-enriched libraries also contain genes involved in ribosome biogenesis and assembly, however of different types. Real-time reverse transcription PCR of cold dehydrin and two PR-10 genes, as well as the light harvesting complex b1 genes demonstrates that the gene expression is dependent on species and growth conditions.Electronic supplementary materialThe online version of this article (doi:10.1007/s10142-011-0223-6) contains supplementary material, which is available to authorized users.

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