The debate about the biological species concept - a review

The importance of the species concept in biology has led to a continuing debate about the definition of species. This paper summarizes the recent literature in relation to the ‘biological species concept’ (MAYR 1942). Among the general attributes demanded, possible limitations of the universality and applicability of a species definition are discussed. Three different areas of criticism of the biological species concept are considered: 1. The impracticability of the criterion of reproductive isolation. The demand for more practical criteria is rejected, because reproductive isolation is seen as the factor that produces and maintains species as discrete entities in nature. 2. The inapplicability to non-bisexual organisms. A brief survey of modes of uniparental reproduction and their relative importance suggests that obligatory apomicts are of little evolutionary significance. 3. The inapplicability to multidimensional situations. Despite practical difficulties, the biological species concept is held to apply to organisms separated in space. The impossibility to delimit species in time by reproductive isolation is recognized. Out of two ways to divide continuous evolutionary lineages in time, the phylogenetic approach, which considers only speciation events (cladogenesis), is preferred as it is more objective. A list of recently published alternative definitions of species, none of which is found acceptable, is given. It is concluded that the biological species concept needs not be changed or dismissed on the basis of the discussed criticisms.     

Splicing Kinetics and Coordination Revealed by Direct Nascent RNA Sequencing through Nanopores

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Application of discrete cosine transform to assess the effect of tumor motion variations on the definition of ITV in lung and liver SBRT

PurposeTo use Discrete Cosine Transform to include tumor motion variations on ITV definition of SBRT patients.MethodsData from 66 patients was collected. 2D planar fluoroscopy images (FI) were available for 54 patients. Daily CBCT projections (CBCTp) from 29 patients were employed to measure interfraction amplitude variability. Systematic amplitude variations were obtained from 17 patients with data from both FI and CBCTp.Tumor motion curves obtained from FI were characterized with a Cosine model (CM), based on cosine functions to the power of 2, 4 or 6, and DCT. Performance of both models was evaluated by means of R² coefficient and by comparing their results on Internal Target Volume (ITV) margins against those calculated from original tumor motion curves.Amplitude variations from CBCTp, as well as estimations of baseline shift variations were added to the DCT model to account for their effect on ITV margins.ResultsDCT replicated tumor motion curves with a mean R² values for all patients of 0.86, 0.91 and 0.96 for the lateral (LAT), anterior-posterior (AP) and cranio-caudal (CC) directions respectively. CM yielded worst results, with R² values of 0.64, 0.61 and 0.74 in the three directions.Interfraction amplitude variation increased ITV margins by a 9%, while baseline shift variability implied a 40% and 80–100% increase for normalized values of baseline shift of 0.2 and 0.4 respectively.ConclusionsProbability distribution functions of tumor positions can be successfully characterized with DCT. This permits to include tumor motion variablilities obtained from patient population into patient specific ITVs.     

文化景观作为区域景观研究概念——德国图林根州文化景观研究、教学与规划实践

近20 年来,对风景园林的文化阐释成为埃尔夫特应用科技大学文化景观研究组持续以来的关注焦点。期间,该研究组系统地分析了决定图林根州文化景观的各种文化因素和要素,深入了解文化和自然环境中的复杂相互作用,以此来表述和研究图林根州的区域景观系统。首先,阐述了当下德国风景园林学术语境中“文化景观”的含义,强调文化对于景观质量的价值。继而,论述了对景观进行优化、保护和设计中无法否定和回避的文化与经济因素。这样既要发展经济又要保护文化的矛盾性质,是文化景观概念所理解的人类生存的重要性质所在。文化景观研究能够在看似统一的地理区域中,形成和发展为具有可识别性的、差异化的动态结构。此外,文化景观研究还涉及其他因素,诸如生物多样性与文化多样性的丧失、生态系统服务功能滞后、经济价值的低估、国土空间连接性以及缺少实质性评价的人文特征。对历史性文化景观价值的认知给风景园林学带来了机遇,对历史景观不仅要保护,而且要创造并提供各种富有成效的展示,以参与文化景观的未来发展。维护和整合风景园林规划设计中文化景观遗产的研究实践,可以通过基础设施项目的环境影响评估到建成区的景观设计整体过程中得以贯彻。更好地理解文化景观,有助于在空间规划和发展中对其更加谨慎地进行处理,以提高文化景观研究的科学和策略意识。     

High‐definition optical coherence tomography of melanocytic skin lesions

High‐definition optical coherence tomography (HD‐OCT) scanners have recently been developed. We assessed micromorphological HD‐OCT correlates of benign naevi (BN) and malignant melanoma (MM). 28 BN and 20 MM were studied using HD‐OCT and histology. Epidermal honeycomb/cobblestone pattern, regular junctional cell nests, and edged papillae are more often observed in BN, whereas fusion of rete ridges, pagetoid cells and junctional and/or dermal nests with atypical cells are more frequently seen in MM. A high overlap of HD‐OCT features in BN and MM was observed and in 20% of MM we did not find evidence for malignancy in OCT images at all. Using HD‐OCT it is possible to visualize architectural and cellular alterations of melanocytic skin lesions. The overlap of HD‐OCT features seen in BN and MM and the absence of suspicious HD‐OCT features in some MM represents an important limitation of HD‐OCT affecting the sensitivity of HD‐OCT in diagnosing MM.

High‐definition optical coherence tomography and the corresponding vertically sectioned histology of a compound naevus.     

Defining CO2 and O2 syndromes of marine biomes in the Anthropocene

Research efforts have intensified to foresee the prospects for marine biomes under climate change and anthropogenic drivers over varying temporal and spatial scales. Parallel with these efforts is the utilization of terminology, such as ‘ocean acidification’ (OA) and ‘ocean deoxygenation’ (OD), that can foster rapid comprehension of complex processes driving carbon dioxide (CO₂) and oxygen (O₂) concentrations in the global ocean and thus, are now widely used in discussions within and beyond academia. However, common usage of the terms ‘acidification’ and ‘deoxygenation’ alone are subjective and, without adequate contextualization, have the potential to mislead inferences over drivers that may ultimately shape the future state of marine ecosystems. Here we clarify the usage of the terms OA and OD as global, climate change‐driven processes and discuss the various attributes of elevated CO₂ and reduced O₂ syndromes common to coastal ecosystems. We support the use of the existing terms ‘coastal acidification’ and ‘coastal deoxygenation’ because they help differentiate the sometimes rapid and extreme nature of CO₂ and O₂ syndromes in coastal ecosystems from the global, climate change‐driven processes of OA and OD. Given the complexity and breadth of the processes involved in altering CO₂ and O₂ concentrations across marine ecosystems, we provide a workflow to enable contextualization and clarification of the usage of existing terms and highlight the close link between these two gases across spatial and temporal scales in the ocean. These distinctions are crucial to guide effective communication of research within the scientific community and guide policymakers responsible for intervening on the drivers to secure desirable future ocean states.     

Occurrence of Halococcus spp. in the nostrils salt glands of the seabird Calonectris diomedea

The nostrils of the seabird Calonectris diomedea are endowed with a salt-excreting gland that could produce a suitable environment for the colonization of extreme halophilic prokaryotes. We have studied in this organ the presence of extreme halophiles by means of culturing techniques. We could easily cultivate members of haloarchaea, and all cultures studied were identified as members of one of the two species Halococcus morrhuae and Hcc. dombrowskii. In order to reveal the diversity of these colonizers, we undertook a taxonomic study. Altogether, the results indicated that members of the genus Halococcus may constitute a part of the natural epizootic microbiota of C. diomedea, and that they exhibit such an important degree of taxonomic variability that appeals for a pragmatic species definition. This seabird nests in the west Mediterranean coasts, but its migratory habits, reaching locations as distant from the Mediterranean as the South Atlantic, may help in the dispersal mechanisms of haloarchaea through the Earth’s surface.     

A Call for More Nuanced Dialogues About Trophy Hunting

Reported effects of trophy harvest often are controversial. The subject is nuanced and many studies lack details necessary to place their results in context. Consequently, many studies are misunderstood or their conclusions misapplied. We propose that all dialogues about trophy hunting include a definition of how they use the term trophy, details of variables measured and why they were selected, and explanations of temporal and spatial scales employed. Only with these details can potential effects of trophy hunting be understood in context and used for management and policy decisions. © 2021 The Wildlife Society.     

基于内容分析法的生态旅游内涵辨析

随着生态旅游的流行与快速发展对生态旅游这个术语的概念也不断的增长扩散.由于缺乏对其内涵的科学认知和梳理,生态旅游概念的应用具有泛化的危险.不断涌现出的大量有关生态旅游的概念给学术研究和旅游管理带来了许多困惑.运用内容分析的方法对中外旅游文献近10～15a内有影响力的40个生态旅游概念进行了分析,提炼出生态旅游概念中最频繁出现的能代表其内涵的6个标准,它们是：以自然为基础、对保护的贡献、当地社区受益、环境教育、道德规范与责任和可持续性.通过对这些标准的识别,结合先前的生态旅游概念,本文对生态旅游的概念在操作层面上进行了重新架构,将生态旅游这一术语定义为：生态旅游是以可持续旅游和伦理道德规范原则为指导,在旅游过程中强调环境教育、影响管理和社区受益,并为其所依赖的环境保护做贡献的负责任的自然之旅.