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排序方式: 共有147条查询结果,搜索用时 15 毫秒
71.
72.
Modelling the occurrence of threatened plant species in taiga landscapes: methodological and ecological perspectives 总被引:1,自引:0,他引:1
Miia Parviainen Miska Luoto Terhi Ryttäri Risto K. Heikkinen 《Journal of Biogeography》2008,35(10):1888-1905
Aim Understanding the spatial patterns of species distribution and predicting the occurrence of high biological diversity and rare species are central themes in biogeography and environmental conservation. The aim of this study was to model and scrutinize the relative contributions of climate, topography, geology and land‐cover factors to the distributions of threatened vascular plant species in taiga landscapes in northern Finland. Location North‐east Finland, northern Europe. Methods The study was performed using a data set of 28 plant species and environmental variables at a 25‐ha resolution. Four different stepwise selection algorithms [Akaike information criterion (AIC), Bayesian information criterion (BIC), adaptive backfitting, cross selection] with generalized additive models (GAMs) were fitted to identify the main environmental correlates for species occurrences. The accuracies of the distribution models were evaluated using fourfold cross‐validation based on the area under the curve (AUC) derived from receiver operating characteristic plots. The GAMs were tentatively extrapolated to the whole study area and species occurrence probability maps were produced using GIS techniques. The effect of spatial autocorrelation on the modelling results was also tested by including autocovariate terms in the GAMs. Results According to the AUC values, the model performance varied from fair to excellent. The AIC algorithm provided the highest mean performance (mean AUC = 0.889), whereas the lowest mean AUC (0.851) was obtained from BIC. Most of the variation in the distribution of threatened plant species was related to growing degree days, temperature of the coldest month, water balance, cover of mire and mean elevation. In general, climate was the most powerful explanatory variable group, followed by land cover, topography and geology. Inclusion of the autocovariate only slightly improved the performance of the models and had a minor effect on the importance of the environmental variables. Main conclusions The results confirm that the landscape‐scale distribution patterns of plant species can be modelled well on the basis of environmental parameters. A spatial grid system with several environmental variables derived from remote sensing and GIS data was found to produce useful data sets, which can be employed when predicting species distribution patterns over extensive areas. Landscape‐scale maps showing the predicted occurrences of individual or multiple threatened plant species may provide a useful basis for focusing field surveys and allocating conservation efforts. 相似文献
73.
Differential localization of HDAC4 orchestrates muscle differentiation 总被引:11,自引:0,他引:11
Miska EA Langley E Wolf D Karlsson C Pines J Kouzarides T 《Nucleic acids research》2001,29(16):3439-3447
74.
A survey of type I interferons from a marsupial and monotreme: implications for the evolution of the type I interferon gene family in mammals 总被引:1,自引:0,他引:1
Sequence data for type I interferons (IFNs) have previously only been available for birds and eutherian ('placental') mammals, but not for the other two groups of extant mammals, the marsupials and monotremes. This has left a large gap in our knowledge of the evolutionary and functional relationships of what is a complex gene family in eutherians. In this study, a PCR-based survey of type I IFN genes from a marsupial, the tammar wallaby (Macropus eugenii), and a monotreme, the short-beaked echidna (Tachyglossus aculeatus), was conducted. Along with Southern blot and phylogenetic analysis, this revealed a large number of type I IFN genes for the wallaby, rivalling that of eutherians, but relatively few type I IFN genes in the echidna. The wallaby genes include both IFNA and IFNB orthologues, indicating that the gene duplication leading to these subtypes occurred prior to the divergence of marsupials and eutherians some 130 million years ago. Results from this study support the idea that the expansion of type I IFN gene complexity in mammals coincides with a concomitant expansion in the functionality of these molecules. For example, this expansion in complexity may have, at least partially, facilitated the evolution of viviparity in marsupials and eutherians. Other evolutionary aspects of these sequences are also discussed. 相似文献
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76.
Biotic interactions are known to affect the composition of species assemblages via several mechanisms, such as competition and facilitation. However, most spatial models of species richness do not explicitly consider inter‐specific interactions. Here, we test whether incorporating biotic interactions into high‐resolution models alters predictions of species richness as hypothesised. We included key biotic variables (cover of three dominant arctic‐alpine plant species) into two methodologically divergent species richness modelling frameworks – stacked species distribution models (SSDM) and macroecological models (MEM) – for three ecologically and evolutionary distinct taxonomic groups (vascular plants, bryophytes and lichens). Predictions from models including biotic interactions were compared to the predictions of models based on climatic and abiotic data only. Including plant–plant interactions consistently and significantly lowered bias in species richness predictions and increased predictive power for independent evaluation data when compared to the conventional climatic and abiotic data based models. Improvements in predictions were constant irrespective of the modelling framework or taxonomic group used. The global biodiversity crisis necessitates accurate predictions of how changes in biotic and abiotic conditions will potentially affect species richness patterns. Here, we demonstrate that models of the spatial distribution of species richness can be improved by incorporating biotic interactions, and thus that these key predictor factors must be accounted for in biodiversity forecasts. 相似文献
77.
Peter Sarkies Murray E. Selkirk John T. Jones Vivian Blok Thomas Boothby Bob Goldstein Ben Hanelt Alex Ardila-Garcia Naomi M. Fast Phillip M. Schiffer Christopher Kraus Mark J. Taylor Georgios Koutsovoulos Mark L. Blaxter Eric A. Miska 《PLoS biology》2015,13(2)
Small RNA pathways act at the front line of defence against transposable elements across the Eukaryota. In animals, Piwi interacting small RNAs (piRNAs) are a crucial arm of this defence. However, the evolutionary relationships among piRNAs and other small RNA pathways targeting transposable elements are poorly resolved. To address this question we sequenced small RNAs from multiple, diverse nematode species, producing the first phylum-wide analysis of how small RNA pathways evolve. Surprisingly, despite their prominence in Caenorhabditis elegans and closely related nematodes, piRNAs are absent in all other nematode lineages. We found that there are at least two evolutionarily distinct mechanisms that compensate for the absence of piRNAs, both involving RNA-dependent RNA polymerases (RdRPs). Whilst one pathway is unique to nematodes, the second involves Dicer-dependent RNA-directed DNA methylation, hitherto unknown in animals, and bears striking similarity to transposon-control mechanisms in fungi and plants. Our results highlight the rapid, context-dependent evolution of small RNA pathways and suggest piRNAs in animals may have replaced an ancient eukaryotic RNA-dependent RNA polymerase pathway to control transposable elements. 相似文献
78.
HDAC4 deacetylase associates with and represses the MEF2 transcription factor. 总被引:28,自引:0,他引:28
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E A Miska C Karlsson E Langley S J Nielsen J Pines T Kouzarides 《The EMBO journal》1999,18(18):5099-5107
79.
The regional species richness and genetic diversity of Arctic vegetation reflect both past glaciations and current climate
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Lærke Stewart Inger G. Alsos Christian Bay Amy L. Breen Christian Brochmann Noémie Boulanger‐Lapointe Olivier Broennimann Helga Bültmann Peder Klith Bøcher Christian Damgaard Fred J. A. Daniëls Dorothee Ehrich Pernille Bronken Eidesen Antoine Guisan Ingibjörg Svala Jónsdóttir Jonathan Lenoir Peter C. le Roux Esther Lévesque Miska Luoto Jacob Nabe‐Nielsen Peter Schönswetter Andreas Tribsch Liv Unn Tveraabak Risto Virtanen Donald A. Walker Kristine B. Westergaard Nigel G. Yoccoz Loïc Pellissier 《Global Ecology and Biogeography》2016,25(4):430-442
80.