摘要： 路县故城遗址既是北京最重要的大遗址之一,也是北京城市副中心迄今所知年代最早的遗址。专家评价,城市建设中,完整地保护一座新发现汉代县城遗址并建设遗址公园,在全国范围内绝无仅有。"路县故城的全面保护,留下了北京的‘根’与‘魂’,不仅对北京城市副中心建设,也对大遗址保护、文化建设、京津冀协同发展、中华民族优秀传统文化继承和弘扬,都有着示范、深远、积极的影响",参与路县考古的北京市文物研究所相关负责人曾这样评价路县故城遗址公园的建设。

关键词： gallery forests   hominins   last common ancestor   paleoecology   strontium isotopes  

摘要： Objectives Riparian or gallery forests are critical habitats for numerous plants and animals today. Paleoanthropologically, reliance on such habitats informs behavioral and ecological reconstructions;for example, gallery forest habitats likely played a critical role in the transition from ape to hominin in the early Pliocene and may represent a preferred habitat for the last common ancestor of chimpanzees and humans. Direct indicators for gallery forest habitats preference are lacking. The objective of this article is to assess whether strontium isotope ratios are a reliable indicator of habitat preference for fauna living in and around gallery forests. Materials and methods We report bioavailable strontium isotope ratios from the Mugiri River, its tributaries, and its gallery forest (Toro-Semliki Wildlife Reserve, southwestern Uganda), and compare them to surrounding savanna-grassland values. We compare these environmental values to strontium isotopes ratios in faunal tooth enamel to determine if habitat preferences are accurately reflected. Results Gallery forest and savanna-grassland vegetations have significantly different strontium isotope ratio profiles. We trace these isotopic differences to the influence of the Mugiri tributaries, which originate on Paleoproterozoic gneiss deposits on top of the surrounding escarpments. These isotopic differences in vegetation are mirrored in the tissues of fauna with habitat preferences for either the gallery forest or the surrounding grasslands. Discussion This research demonstrates the potential of strontium isotope ratios to identify habitat preferences in modern or fossil fauna under proper geologic variability. It provides a methodological model for future studies seeking to reconstruct habitat preferences in early hominins.

关键词： Species trees   Gene trees   Divergence times   Phylogenomics   Substitution models   Exons  

摘要： BackgroundThe flood of genomic data to help build and date the tree of life requires automation at several critical junctures, most importantly during sequence assembly and alignment. It is widely appreciated that automated alignment protocols can yield inaccuracies, but the relative impact of various sources error on phylogenomic analysis is not yet known. This study employs an updated mammal data set of 5162 coding loci sampled from 90 species to evaluate the effects of alignment uncertainty, substitution models, and fossil priors on gene tree, species tree, and divergence time estimation. Additionally, a novel coalescent likelihood ratio test is introduced for comparing competing species trees against a given set of gene *** aligned DNA sequences of 5162 loci from 90 species were trimmed and filtered using trimAL and two filtering protocols. The final dataset contains 4 sets of alignments - before trimming, after trimming, filtered by a recently proposed pipeline, and further filtered by comparing ML gene trees for each locus with the concatenation tree. Our analyses suggest that the average discordance among the coalescent trees is significantly smaller than that among the concatenation trees estimated from the 4 sets of alignments or with different substitution models. There is no significant difference among the divergence times estimated with different substitution models. However, the divergence dates estimated from the alignments after trimming are more recent than those estimated from the alignments before *** results highlight that alignment uncertainty of the updated mammal data set and the choice of substitution models have little impact on tree topologies yielded by coalescent methods for species tree estimation, whereas they are more influential on the trees made by concatenation. Given the choice of calibration scheme and clock models, divergence time estimates are robust to the choice of substitution models, but remo

关键词： 灵长类动物   身手敏捷   树鼩   松鼠  

摘要： 你爱吃辣味的食物吗?或许,你"吃辣"的本事还比不上一只小动物。它就是树鼩。它长相可爱,很像松鼠,却和灵长类动物关系更为密切。树鼩主要分布在东南亚各国以及中国大陆的南方地区,喜欢生活在热带和亚热带的森林、灌木丛、村落附近。它身手敏捷,喜欢以虫类为主食,食谱上还有幼鸟、鸟蛋、谷类、果类、树叶等美味。和松鼠一样,树鼩的吃相也很可爱。但是如果你真正了解它,定会对它刮目相看的。

关键词： alternative stable states   equilibrium versus nonequilibrium dynamics   grazing management   reversible degradation   vegetation collapse   vegetation patch dynamics  

摘要： Many arid and semi-arid rangelands exhibit distinct spatial patterning of vegetated and bare soil-dominated patches. The latter potentially represent a grazing-induced, degraded ecosystem state, but could also arise via mechanisms related to feedbacks between vegetation cover and soil moisture availability that are unrelated to grazing. The degree to which grazing contributes to the formation or maintenance of degraded patches has been widely discussed and modeled, but empirical studies of the role of grazing in their formation, persistence, and reversibility are limited. We report on a long-term (17 years) grazing removal experiment in a semi-arid savanna where vegetated patches composed of perennial grasses were interspersed within large (>10 m(2)) patches of bare soil. Short-term (3 years) grazing removal did not allow bare patches to become revegetated, whereas following long-term (17 years) grazing removal, bare soil patches were revegetated by a combination of stoloniferous grasses and tufted bunchgrasses. In the presence of grazers, stoloniferous grasses partially recolonized bare patches, but this did not lead to full recovery or to the establishment of tufted bunchgrasses. These results show that grazers alter both the balance between bare and vegetated patches, as well as the types of grasses dominating both patch types in this semiarid savanna. Synthesis: Large herbivores fundamentally shaped the composition and spatial pattern of the herbaceous layer by maintaining a two-phase herbaceous mosaic. However, bare patches within this mosaic can recover given herbivore removal over sufficiently long time scales, and hence do not represent a permanently degraded ecosystem state.

关键词： Aquatic community structure   aquatic trophic chain   ecosystem functioning   leaf litter decomposition   tropical   stream  

摘要： Litter breakdown is an important ecological process at the bottom of food webs in streams. Previous studies have been based only on a temporal interval of a single season, thus ignoring seasonal variation in litter input and community structure. We investigated organic matter input in a Brazilian savanna stream and the influence of its associated hyphomycetes on the invertebrate community. Organic matter input was sampled monthly and the leaves submitted to decomposition experiments. There were lower breakdown rates and higher invertebrate species richness and abundance during the dry season, which reached their maximum in July due to low stream discharge. Invertebrate composition was best explained by hyphomycetes (mainly by Flagellospora curvula and Anguillospora filiformis). Hyphomycetes have the capacity to degrade complex compounds of litter and to rapidly absorb nutrients by growing branched filaments, thus making the leaves more favourable for consumption by invertebrates. Shredder abundance was negatively related to litter richness, indicating possible species-specific relationships. We observed a sequential process with increased leaf litter input promoting an increase in hyphomycetes biomass, which in turn favoured invertebrate density.

关键词： cercariae   malformation   Common Hourglass Tree Frog   Polypedates cruciger   resistance   survival   tolerance  

摘要： Tolerance and resistance to parasites are defense strategies of host organisms. Here, we tested the development-dependent tolerance and resistance of Polypedates cruciger Blyth, 1852 tadpoles to trematode infection. We exposed the tadpoles at Gosner stages 27, 28-29, and 30-31 to two types of cercariae (furcocercous and pleurolophocercous cercariae of Acanthostomum burminis (Bhalerao, 1926)) under laboratory conditions. To determine tolerance (the ability of a host to limit health effects of a given parasite load), we exposed the tadpoles until all cercariae penetrated the host. As a measure of determining resistance, we exposed tadpoles to cercariae for a limited time and counted the number of cercariae penetrating the tadpoles. The survival of tadpoles exposed at early stages was significantly lower than that of tadpoles exposed at later stages (mixed-effect model, p < 0.05), suggesting an age-dependent tolerance to parasitism. Tadpoles exposed at early stages were also smaller, took longer to metamorphosis, showed lower resistance to parasitism (ANOVA, p < 0.001), and developed axial malformations. In the resistance experiment, fewer parasites penetrated later stage tadpoles than early stage tadpoles. Tadpoles of P. cruciger showed a development-dependent tolerance and resistance to parasitism, resulting in greater survival and fewer malformations when parasitism occurs at late stages.

关键词： arthropods   biological invasion   forest fragments   habitat alternation   invasive plants   multi-taxonomic approach   non-crop habitats   Robinia pseudoacacia  

摘要： Aim Landscape simplification and the spread of invasive species are considered beyond the main threats to global biodiversity. It is well recognized that non-crop habitats bring complexity to farmland and provide refuge for a wide range of organisms, including arthropods. However, knowledge about the effects of invasive trees on arthropods in non-crop habitats in intensive agricultural landscapes is still weak. Therefore, we examined differences in the arthropod assemblages between woodlots formed by the invasive black locust (Robinia pseudoacacia L.) and by native deciduous tree species in the intensive agricultural landscape. Location Czech Republic, Central Europe. Methods We used a multi-taxonomic approach to record arthropod assemblages using various sampling methods. The impacts of woodlot habitat structure were investigated across 13 arthropod taxa from different trophic levels. Results Total abundance and species richness of all arthropods and the majority of the herbivore taxa were lower in R. pseudoacacia woodlots, likely due to losses of the forest canopy specialists. The forest specialists were associated with the native woodlots with more developed canopy and shrub layers. The impoverished diversity of the forest specialists and canopy herbivores in the R. pseudoacacia woodlots was partly compensated by the higher presence of species exploiting a well developed herb layer and open-habitat specialists, including threatened species. Main conclusions Native woodlots and those formed by R. pseudoacacia differ in vegetation structure and host different assemblages of arthropods. Therefore, parallel presence of both types of woodlots supports arthropod diversity in otherwise simplified agricultural landscapes through creating more complex mosaic of habitats.

关键词： assemblages   biodiversity   hydromorphic soils   invasive alien species   plantations   restoration  

摘要： Many wetland systems are being lost or degraded by human activities such as plantation forestry. Therefore, efforts to restore these wetland systems are important for biodiversity recovery. We assess the recovery of arthropod assemblages that occupy hydromorphic grassland topsoil and leaf litter after the removal of exotic pine trees. We sampled arthropods in three biotopes (natural untransformed hydromorphic grasslands, restored hydromorphic grasslands, and commercial pine plantations) replicated across a large-scale timber-grassland mosaic in the KwaZulu-Natal Midlands, South Africa. In the restored sites, overall species richness, as well as species richness of spiders, ants, and orthopterans, was significantly higher than in plantations, and was as high as in natural, untransformed sites. Additionally, overall assemblage structure along with spider, beetle, ant, and orthopteran assemblages showed no significant differences between restored and natural grasslands. Therefore, pine tree removal enables recovery of these arthropod taxa to levels similar to those in natural hydromorphic grassland. Recovery was rapid, with the assemblages in some restored sites resembling those in untransformed sites after only 6 years, indicating a high level of resilience and recovery in these systems. Contrary to expectations, time since pine removal had a negative effect on arthropod recovery. This was due to the strongly negative effect of alien invasive American bramble (Rubus cuneifolius), which was most common in older restored sites, causing deviation from their restoration trajectory. The potential for arthropod recovery in these hydromorphic grasslands is high, but successful restoration is dependent on ongoing appropriate grassland management, especially removal of bramble.

摘要： Wildlife trade is a multibillion dollar industry that is driving species toward extinction. Of >31,500 terrestrial bird, mammal, amphibian, and squamate reptile species, similar to 18% (N = 5579) are traded globally. Trade is strongly phylogenetically conserved, and the hotspots of this trade are concentrated in the biologically diverse tropics. Using different assessment approaches, we predict that, owing to their phylogenetic replacement and trait similarity to currently traded species, future trade will affect up to 3196 additional species-totaling 8775 species at risk of extinction from trade. Our assessment underscores the need for a strategic plan to combat trade with policies that are proactive rather than reactive, which is especially important because species can quickly transition from being safe to being endangered as humans continue to harvest and trade across the tree of life.