滦河流域河岸带入侵植物分布特征及其与环境的关系

根据滦河流域河岸带56个样点的植被调查,研究入侵植物种类,其组成特征、空间分布,及其与环境因子的关系.结果表明: 滦河流域河岸带共记录入侵植物26种,属12科19属,其中菊科和苋科植物为优势科,占入侵植物总数的50%,一年生植物占总数的73.1%,反枝苋、大狼杷草、小藜是出现频数最高的3种植物;样点的入侵种数、入侵强度与海拔呈显著负相关;人类活动强度对入侵植物分布有显著影响,人口密集、交通便利、人类活动频繁的平原区,水库众多的浅山区,以及中游段旅游业发达的承德市周边山区是入侵植物集中分布的区域;人口分布较稀的高原地区只出现几种宽生态幅的入侵物种.总体上,滦河流域河岸带入侵等级高的植物主要分布在400 m以下的中低海拔地区,除反枝苋外,其他高等级入侵物种尚未扩散进入高海拔地区.     

Phylogenetic signals in thermal traits remain stronger in the tropics if we can believe published physiological data. A reply to McKechnie et al., “Data quality problems undermine analyses of endotherm upper critical temperatures”

Due to concerns about data quality, McKechnie, Coe, Gerson, and Wolf ( 2016 ) questioned the conclusions of our study (Khaliq et al., 2015 ) published in this journal. Here, we argue that most of the questioned data points are in fact useful for macrophysiological analyses, mostly because the vast majority of data are explicitly reported in the peer‐reviewed physiological literature. Furthermore, we show that our conclusions remain largely robust irrespective of the data inclusion criterion. While we think that constructive debates about the adequate use of primary data in meta‐studies as well as more transparency in data inclusion criteria are indeed useful, we also emphasize that data suitability should be evaluated in the light of the scope and scale of the study in which they are used. We hope that this discussion will not discourage the exchange between disciplines such as biogeography and physiology, as this integration is needed to address some of the most urgent scientific challenges.     

大连长山群岛海岸带沉积物微生物群落结构特征

【目的】为揭示海岸带微生物群落结构在人类活动影响下的分布差异及对环境因子变化的响应趋势,【方法】本实验采用t-RFLP和DGGE技术,对大连长山群岛不同功能类型海岸潮间带沉积物中的微生物群落结构特征进行比对和分析,并通过16S rRNA基因文库解析养殖污染站位的微生物群落结构特征。【结果】T-RFLP的t-RF分析显示,养殖污染严重站位的微生物丰度、香农指数和均匀度明显高于其它站位。通过对t-RFLP色谱峰和DGGE图谱聚类分析发现,处于旅游区的2个站位微生物群落结构相似度较高,养殖区随污染程度加重与旅游区的群落结构差异增大。对污染严重站位建立的克隆文库显示变形菌门(Proteobacteria)为优势菌群,其中γ-变形菌门是主要存在的亚门微生物。【结论】T-RFLP和DGGE技术从不同方面反映了环境中的微生物群落结构特征,研究结果表明养殖污染区的微生物群落结构发生明显变化,其影响大于地理隔离效应,污染严重区域的微生物群落中存在大量肠杆菌属,且多个物种与富营养化和赤潮相关联,如拟杆菌门和α-变形细菌红细菌目的细菌。     

The rapid and long-lasting growth of grasses following small falls of rain on stony downs in the arid interior of Australia

Abstract Stony downs consist of grassy areas that alternate with areas that have a substantial stone cover. The stone-covered areas are impermeable, and most rain falling on them runs off, substantially increasing the effective rainfall in adjacent grassy areas. As a result, 20–25 mm of rain on stony downs wetted the soil around the grass to a depth of 140–170 mm and allowed sustained grass response. This is much less than the 35–40 mm of rain required for the same response on red clay or grey clay plains. Grasses respond very rapidly after rain. Some have green shoots the day after rain, and all have responded by the second day. Ephemerals dry off in 4–6 weeks, but most tussock grasses still have some green foliage 8–10 weeks after rain. Deeper rooted tussock grasses remain green for so long because most of the moisture that reaches deeper roots after rain remains there. Most moisture loss is through the soil surface and is recognizable as a drying front that descends through the soil profile. Soil above the drying front is nearly air dry (<5% moisture) while soil below the front has substantial moisture (14–16%). By about a month after rain in summer, the drying front is at a depth of about 80–120 mm. This is near the tips of the roots of ephemeral grasses and the ephemerals then dry off rapidly. Only the tips of the leaves of deep rooted grasses like Mitchell grass (Astrebla spp.) dry off. Their leaves continue to remain mostly green during most of the second month after rain and they do not dry off completely until the third month when the drying front reaches the bottom of the main root system.     

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae,Senecioneae) along an altitudinal gradient in Harz National Park (Germany)

Introgressive hybridization of Senecio hercynicus and S. ovatus (Compositae, Senecioneae) was studied in a hybrid zone on the southern slopes of Mt Brocken (Harz Mountains, Germany). A total of 415 plants representing 10 stands along an altitudinal gradient were investigated using multivariate statistical analyses of morphological characters and molecular markers (random amplified polymorphic DNA[RAPD]). Both types of traits detected pure S. hercynicus stands on the summit plateau, pure S. ovatus stands at the lowest elevations, and hybrid swarms at intermediate elevations. While morphological and molecular patterns coincided, some individuals in hybrid stands combined morphological patterns typical of S. ovatus with RAPD patterns typical of S. hercynicus, and vice versa. In general, introgression was symmetrical within stands, though one stand combined S. ovatus characters with the glandular hair typical for S. hercynicus, and two stands combined a S. hercynicus typical RAPD genotype with morphological characters shifted towards S. ovatus. Because pure stands of S. hercynicus occurred only on the summit plateau of Mt Brocken, and markers typical for S. ovatus were detectable in stands up to 1040 m a.s.l., future fusion or assimilation of the rare form, S. hercynicus, by the more widespread S. ovatus appears possible at Mt Brocken.     

Hybridization and speciation

Hybridization has many and varied impacts on the process of speciation. Hybridization may slow or reverse differentiation by allowing gene flow and recombination. It may accelerate speciation via adaptive introgression or cause near‐instantaneous speciation by allopolyploidization. It may have multiple effects at different stages and in different spatial contexts within a single speciation event. We offer a perspective on the context and evolutionary significance of hybridization during speciation, highlighting issues of current interest and debate. In secondary contact zones, it is uncertain if barriers to gene flow will be strengthened or broken down due to recombination and gene flow. Theory and empirical evidence suggest the latter is more likely, except within and around strongly selected genomic regions. Hybridization may contribute to speciation through the formation of new hybrid taxa, whereas introgression of a few loci may promote adaptive divergence and so facilitate speciation. Gene regulatory networks, epigenetic effects and the evolution of selfish genetic material in the genome suggest that the Dobzhansky–Muller model of hybrid incompatibilities requires a broader interpretation. Finally, although the incidence of reinforcement remains uncertain, this and other interactions in areas of sympatry may have knock‐on effects on speciation both within and outside regions of hybridization.     

Integrative taxonomy reveals a new species of Callisto (Lepidoptera,Gracillariidae) in the Alps

Europe has one of the best-known Lepidopteran faunas in the world, yet many species are still being discovered, especially in groups of small moths. Here we describe a new gracillariid species from the south-eastern Alps, Callisto basistrigella Huemer, Deutsch & Triberti, sp. n. It shows differences from its sister species Callisto coffeella in morphology, the barcode region of the cytochrome c oxidase I gene and the nuclear gene histone H3. Both Callisto basistrigella and Callisto coffeella can co-occur in sympatry without evidence of admixture. Two Callisto basistrigella specimens show evidence of introgression. We highlight the importance of an integrative approach to delimit species, combining morphological and ecological data with mitochondrial and nuclear sequence data. Furthermore, in connection with this study, Ornix blandella Müller-Rutz, 1920, syn. n. is synonymized with Callisto coffeella (Zetterstedt, 1839).     

Phytomass change in natural phytocenosis as an indicator of technogenic pollution of soils with heavy metals

This study considered the possibility of using plant community phytomass for the assessment of soil pollution with heavy metals (HM) from industrial wastes. The three-year-long field experiment was run under the regional natural meadow vegetation; the polymetallic galvanic slime was used as an industrial waste contaminant. It is shown that soil contamination primarily causes decrease of phytomass in the growing phytocenosis. The vegetation experiments determined nonlinear dependence of cultivated and wild plant biomass on the level of soil contamination; it is described by the equations of logistic and Gaussian regression. In the absence of permanent contaminants, the soil is self-cleaned over time. It reproduces phytomass mainly due to the productivity increase of the most pollution-tolerant species in the remaining phytocenosis. This phenomenon is defined as environmental hysteresis. Soil pollution by industrial waste leads to the loss of plant biodiversity. The research shows that the study of the HM impact on ecosystems is expedient given the consideration of the “soil–phytocenosis–pollutant” complex in the “dose–response” aspect. The reaction of phytocenosis on HM showing decline in phytomass leads to serious limitations in the choice of accumulating plants, because the adsorbed HM are rejected through phytomass.     

Phylogeography of the Lacerta viridis complex: mitochondrial and nuclear markers provide taxonomic insights

Based on broad, nearly rangewide sampling, we reanalysed the phylogeography of the Lacerta viridis complex using the mitochondrial cytochrome b gene and the intron 7 of the nuclear β‐fibrinogen gene. Using the mitochondrial marker, we identified in phylogenetic analyses 10 terminal clades clustering in four deeply divergent main lineages whose relationships are weakly resolved. These lineages correspond to Lacerta bilineata, L. viridis, the previously identified Adriatic or West Balkan lineage and a newly discovered fourth lineage from the Anatolian Black Sea coast and the south‐eastern Balkan Peninsula. Except for the latter lineage, there is considerable phylogeographic structuring in each lineage, with higher diversity in the south of the distribution ranges. This pattern indicates the existence of two distinct microrefugia in the Italian Peninsula and Sicily and of up to seven microrefugia in the Balkan Peninsula, but of only one refugium along the Black Sea coast of Anatolia. We identified secondary contact zones of the main lineages and of terminal clades within these lineages. However, most of the formerly described putative contact zone of L. bilineata and L. viridis turned out to be a contact zone between the Adriatic lineage and L. viridis, but L. bilineata seems to be involved only marginally. Our nuclear marker could not unambiguously resolve whether there is gene flow in contact zones. Thus, further research is necessary to decide whether the four main lineages are conspecific or whether they represent distinct biological species. We restrict the name L. v. meridionalis to the newly identified genetic lineage from Turkey and south‐eastern Europe, synonymize some previously recognized taxa and suggest a tentative nomenclature for the L. viridis complex.