用Brainerd-Robinson方法比较华北地区几个主要晚更新世化石动物群的年代顺序

本文尝试用Brainerd-Robinson方法分析华北地区六个主要动物群相对年代的先后,讨论了方法的原理及所采用的判断标准。所得顺序为丁村、许家窑、萨拉乌苏、峙峪、小南海和山顶洞,与绝对年龄数据和旧石器考古工作者的一般认识相符。这表明在一定的条件下,用B-R方法来分析动物群相对年代的先后是可行的。     

Coliboaia is not Chauvet

The decorated cave of Coliboaia in Romania has been claimed to date to the Aurignacian period, and to supply support for the Aurignacian attribution of France's Chauvet cave. In this paper, we examine the evidence and show that neither the radiocarbon dates obtained at Coliboaia nor the style and content of its cave art correspond to the Aurignacian period, and that comparisons with Chauvet cave – itself badly dated and erroneously attributed – are equally ill-founded. We also show that both caves are in regions which are bereft of Aurignacian occupation, and neither cave contains any artefacts from the period.     

Genetic and morphologic diversity of the moles (Talpomorpha,Talpidae, Mogera) from the continental Far East

Taxonomy of the East Asian moles of the genus Mogera is still controversial. Based on the sequence data of 12 nuclear genes and one mitochondrial gene, we examine genetic variation in the Mogera wogura species complex and demonstrate that M. robusta, from the continental Far East, and M. wogura, from the Japanese Islands, are not conspecific. Our data do not support the existence of two or more species of Mogera in the Russian Far East. We suggest that the form “coreana” from the Korean Peninsula should be treated as a subspecies of M. robusta. Our morphological analysis shows that M. r. coreana differs from typical M. robusta, from Primorye, primarily in its smaller size. We show that there is strong morphological variability among continental moles, which may be associated with ecological and geographical factors. The time since the split between M. wogura s. str. and M. robusta dates back to the Middle Pleistocene (0.30–1.0 Myr), while M. r. coreana separated from M. r. robusta in the Upper Pleistocene (0.04–0.18 Myr). The results of the mismatch analysis indicate recent demographic expansion in populations of moles from Primorye.     

Luminescence in Li2BaP2O7

The photo‐, thermo‐ and optically stimulated luminescence in Li₂BaP₂O₇ activated with Eu²⁺/Cu⁺ are reported. Strong thermoluminescence, which is about two times greater than LiF‐TLD 100 was observed in the Eu²⁺‐activated sample. It also exhibited optically stimulated luminescence sensitivity of ~20% that of commercial Al₂O₃:C phosphor. Copyright © 2014 John Wiley & Sons, Ltd.     

Ageing culturally significant relic trees in southeast Queensland to support bushfire management strategies

Appropriate fire management strategies are needed to protect forests and large old ecologically and culturally significant trees in natural landscapes. The aim of this study was to determine the age of large old and relic trees of cultural significance that included Cypress Pine (Callitris columellaris F. Muell.), a species that is sensitive to crown scorching fires in a fire‐prone landscape, and to calibrate a tree‐growth‐rate method for estimating tree age. Twelve large trees were dated using radiocarbon (¹⁴C) dating. The trees are located on North Stradbroke Island (Indigenous name: Minjerribah), southeast Queensland (Australia) in a fire‐prone landscape where recent wildfires have destroyed many large trees. The median tree ages ranged from 155 to 369 years. These results suggest an important role of past Indigenous land management practices in protecting Cypress Pine from crown scorching fires. The tree‐growth‐rate‐based method for estimating tree age generally overestimated the age derived from radiocarbon dating. Bias correction factors were developed for correcting various measures of periodic growth rates. This study provides evidence that appropriate low‐intensity fire strategies have the potential to contribute to the survival of forests and conserve large old trees.     

The ups and downs of the building trade in a medieval city: Tree-ring data as proxies for economic,social and demographic dynamics in Bruges (c. 1200–1500)

The exceptional preservation of the cityscape in the medieval city of Bruges (Belgium) triggered dendrochronological research on numerous preserved roof constructions in historical buildings, that date from the Middle Ages up to the early modern period. As many of these oak timbers lack the preservation of waney edge, a method was developed to combine sapwood estimates of felling dates within each building phase and to compute a summed probability distribution (SPD) for those felling dates. These summed probabilities now allow us to reconstruct temporal trends in building trade activity in an expanding medieval city. When linked to the social status of the patrons of the building projects, it is observed that resilience to demographic crisis and political turmoil differs among the social groups and political elite of a medieval society. Furthermore the dating results of decades of tree-ring research now provide a typo-chronological framework of roof constructions and shows that it took nearly two centuries before more advanced technological skill in the construction of roofs completely replaced the traditional common rafter roofs.     

Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon,without affecting the net carbon balance

Thicker snowpacks and their insulation effects cause winter‐warming and invoke thaw of permafrost ecosystems. Temperature‐dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow‐free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long‐term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter‐warming. By combining ²¹⁰Pb and ¹⁴Cdating of peat cores with peat growth models, we investigated thawing effects on year‐round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter‐warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long‐term responses of whole‐year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.     

An underground burst of diversity – a new look at the phylogeny and taxonomy of the genus Talpa Linnaeus, 1758 (Mammalia: Talpidae) as revealed by nuclear and mitochondrial genes

Using both nuclear and mitochondrial sequences, we demonstrate high genetic differentiation in the genus Talpa and confirm the existence of cryptic species in the Caucasus and Anatolia, namely, T. talyschensis Vereschagin, 1945, T. ognevi Stroganov, 1948, and Talpa ex gr. levantis. Our data support four clades in the genus Talpa that showed strong geographical associations. The ‘europaea’ group includes six species from the western portion of the genus' range (T. europaea, T. occidentalis, T. romana, T. caeca, T. stankovici, and T. levantis s.l.); another three groups are distributed further east: the ‘caucasica’ group (Caucasus), the ‘davidiana’ group (eastern Anatolia and Elburz) and T. altaica (Siberia). The phylogenetic position of T. davidiana was highlighted for the first time. The order of basal branching remains controversial, which can be attributed to rapid diversification events. The molecular time estimates based on nuclear concatenation estimated the basal divergence of the crown Talpa during the latest Miocene. A putative scenario of Talpa radiation and issues of species delimitation are discussed. © 2015 The Linnean Society of London     

Ancient vicariance and climate‐driven extinction explain continental‐wide disjunctions in Africa: the case of the Rand Flora genus Canarina (Campanulaceae)

Transoceanic distributions have attracted the interest of scientists for centuries. Less attention has been paid to the evolutionary origins of ‘continent‐wide’ disjunctions, in which related taxa are distributed across isolated regions within the same continent. A prime example is the ‘Rand Flora’ pattern, which shows sister taxa disjunctly distributed in the continental margins of Africa. Here, we explore the evolutionary origins of this pattern using the genus Canarina, with three species: C. canariensis, associated with the Canarian laurisilva, and C. eminii and C. abyssinica, endemic to the Afromontane region in East Africa, as case study. We infer phylogenetic relationships, divergence times and the history of migration events within Canarina using Bayesian inference on a large sample of chloroplast and nuclear sequences. Ecological niche modelling was employed to infer the climatic niche of Canarina through time. Dating was performed with a novel nested approach to solve the problem of using deep time calibration points within a molecular dataset comprising both above‐species and population‐level sampling. Results show C. abyssinica as sister to a clade formed by disjunct C. eminii and C. canariensis. Miocene divergences were inferred among species, whereas infraspecific divergences fell within the Pleistocene–Holocene periods. Although C. eminii and C. canariensis showed a strong genetic geographic structure, among‐population divergences were older in the former than in the latter. Our results suggest that Canarina originated in East Africa and later migrated across North Africa, with vicariance and aridification‐driven extinction explaining the 7000 km/7 million year divergence between the Canarian and East African endemics.     

The effects of recombination,mutation and selection on the evolution of the Rp1 resistance genes in grasses

Plant immune genes, or resistance genes, are involved in a co‐evolutionary arms race with a diverse range of pathogens. In agronomically important grasses, such R genes have been extensively studied because of their role in pathogen resistance and in the breeding of resistant cultivars. In this study, we evaluate the importance of recombination, mutation and selection on the evolution of the R gene complex Rp1 of Sorghum, Triticum, Brachypodium, Oryza and Zea. Analyses show that recombination is widespread, and we detected 73 independent instances of sequence exchange, involving on average 1567 of 4692 nucleotides analysed (33.4%). We were able to date 24 interspecific recombination events and found that four occurred postspeciation, which suggests that genetic introgression took place between different grass species. Other interspecific events seemed to have been maintained over long evolutionary time, suggesting the presence of balancing selection. Significant positive selection (i.e. a relative excess of nonsynonymous substitutions (d_N/d_S>1)) was detected in 17–95 codons (0.42–2.02%). Recombination was significantly associated with areas with high levels of polymorphism but not with an elevated d_N/d_S ratio. Finally, phylogenetic analyses show that recombination results in a general overestimation of the divergence time (mean = 14.3%) and an alteration of the gene tree topology if the tree is not calibrated. Given that the statistical power to detect recombination is determined by the level of polymorphism of the amplicon as well as the number of sequences analysed, it is likely that many studies have underestimated the importance of recombination relative to the mutation rate.