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991.
Organismal dispersal through mountain passes should be more constrained by temperature‐related differences between lowland and highland sites in montane environments. This may lead to higher rates of diversification through isolation of existing lineages toward the tropics. This mechanism, proposed by Janzen, could influence broad‐scale patterns of biodiversity across mountainous regions and more broadly across latitudinal gradients. We constructed two complementary analyses to test this hypothesis. First, we measured topographically‐derived thermal gradients using recently‐developed climatic data across the Americas, reviewing the main expectations from Janzen's climatic model. Then, we evaluated whether thermal barriers predict assemblage similarity for amphibians and mammals along elevational gradients across most of their latitudinal extent in the Americas. Thermal barriers between low and high elevation areas, initially proposed to be unique to tropical environments, are comparably strong in some temperate regions, particularly along the western slopes of North American dividing ranges. Biotic similarity for both mammals and amphibians decreases between sites that are separated by elevation‐related thermal barriers. That is, the stronger the thermal barrier separating pairs of sites across the latitudinal gradient, the lower the similarity of their species assemblages. Thermal barriers explain 10–35% of the variation in latitudinal gradients of biotic similarity, effects that were stronger in comparisons of sites at high elevations. Mammals' stronger dispersal capacities and homeothermy may explain weaker effects of thermal barriers on gradients of assemblage similarity than among amphibians. Understanding how temperature gradients have shaped gradients of montane biological diversity in the past will improve understanding of how changing environments may affect them in the future. 相似文献
992.
Intrinsic factors drive spatial genetic variation in a highly vagile species,the wedge‐tailed eagle Aquila audax,in Tasmania 下载免费PDF全文
Christopher P. Kozakiewicz Scott Carver Jeremy J. Austin Jill M. Shephard Christopher P. Burridge 《Journal of avian biology》2017,48(7):1025-1034
Knowledge of dispersal in a species, both its quantity and the factors influencing it, are crucial for our understanding of ecology and evolution, and for species conservation. Here we quantified and formally assessed the potential contribution of extrinsic factors on individual dispersal in the threatened Tasmanian population of wedge‐tailed eagle Aquila audax. As successful breeding by these individuals appears strongly related to habitat, we tested the effect of landscape around sampling sites on genetic diversity and spatial genetic variation, as these are influenced by patterns of dispersal. Similarly, we also tested whether habitat intervening sampling sites could explain spatial genetic variation. Twenty microsatellites were scored, but only a small proportion of spatial genetic variation (4.6%) could be explained by extrinsic factors, namely habitat suitability and elevation between sites. However, significant clinal genetic variation was evident across Tasmania, which we explain by intrinsic factors, likely high natal philopatry and occasional long‐distance dispersal. This study demonstrates that spatial genetic variation can be detected in highly vagile species at spatial scales that are small relative to putative dispersal ability, although here there was no substantial relationship with landscape factors tested. 相似文献
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995.
Edwin Hoe Jeremy Anderson Jordan Nathanielsz Zheng Quan Toh Rachel Marimla Anne Balloch Paul V Licciardi 《Microbiology and immunology》2017,61(2):49-56
The human immune system is a tightly regulated network that protects the host from disease. An important aspect of this is the balance between pro‐inflammatory Th17 cells and anti‐inflammatory T regulatory (Treg) cells in maintaining immune homeostasis. Foxp3+ Treg are critical for sustaining immune tolerance through IL‐10 and transforming growth factor‐β while related orphan receptor‐γt+ Th17 cells promote immunopathology and auto‐inflammatory diseases through the actions of IL‐17A, IL‐21 and IL‐22. Therefore, imbalance between Treg and Th17 cells can result in serious pathology in many organs and tissues. Recently, certain IL‐17‐producing cells have been found to be protective against infectious disease, particularly in relation to extracellular bacteria such Streptococcus pneumoniae; a number of other novel IL‐17‐secreting cell populations have also been reported to protect against a variety of other pathogens. In this mini‐review, the dual roles of Treg and Th17 cells are discussed in the context of autoimmunity and infections, highlighting recent advances in the field. Development of novel strategies specifically designed to target these critical immune response pathways will become increasingly important in maintenance of human health. 相似文献
996.
Atomic Layer Deposition of Functional Layers for on Chip 3D Li‐Ion All Solid State Microbattery 下载免费PDF全文
Manon Létiche Etienne Eustache Jeremy Freixas Arnaud Demortière Vincent De Andrade Laurence Morgenroth Pascal Tilmant François Vaurette David Troadec Pascal Roussel Thierry Brousse Christophe Lethien 《Liver Transplantation》2017,7(2)
Nowadays, millimeter scale power sources are key devices for providing autonomy to smart, connected, and miniaturized sensors. However, until now, planar solid state microbatteries do not yet exhibit a sufficient surface energy density. In that context, architectured 3D microbatteries appear therefore to be a good solution to improve the material mass loading while keeping small the footprint area. Beside the design itself of the 3D microbaterry, one important technological barrier to address is the conformal deposition of thin films (lithiated or not) on 3D structures. For that purpose, atomic layer deposition (ALD) technology is a powerful technique that enables conformal coatings of thin film on complex substrate. An original, robust, and highly efficient 3D scaffold is proposed to significantly improve the geometrical surface of miniaturized 3D microbattery. Four functional layers composing the 3D lithium ion microbattery stacking has been successfully deposited on simple and double microtubes 3D templates. In depth synchrotron X‐ray nanotomography and high angle annular dark field transmission electron microscope analyses are used to study the interface between each layer. For the first time, using ALD, anatase TiO2 negative electrode is coated on 3D tubes with Li3PO4 lithium phosphate as electrolyte, opening the way to all solid‐state 3D microbatteries. The surface capacity is significantly increased by the proposed topology (high area enlargement factor – “thick” 3D layer), from 3.5 μA h cm?2 for a planar layer up to 0.37 mA h cm?2 for a 3D thin film (105 times higher). 相似文献
997.
Estimating plant abundance using inflated beta distributions: Applied learnings from a lichen–caribou ecosystem 下载免费PDF全文
Jonah L. Keim Philip D. DeWitt J. Jeremy Fitzpatrick Noemie S. Jenni 《Ecology and evolution》2017,7(2):486-493
Quantifying abundance and distribution of plant species can be difficult because data are often inflated with zero values due to rarity or absence from many ecosystems. Terrestrial fruticose lichens (Cladonia and Cetraria spp.) occupy a narrow ecological niche and have been linked to the diets of declining caribou and reindeer populations (Rangifer tarandus) across their global distribution, and conditions related to their abundance and distribution are not well understood. We attempted to measure effects related to the occupancy and abundance of terrestrial fruticose lichens by sampling and simultaneously modeling two discrete conditions: absence and abundance. We sampled the proportion cover of terrestrial lichens at 438 vegetation plots, including 98 plots having zero lichens. A zero‐inflated beta regression model was employed to simultaneously estimate both the absence and the proportion cover of terrestrial fruticose lichens using fine resolution satellite imagery and light detection and ranging (LiDAR) derived covariates. The probability of lichen absence significantly increased with shallower groundwater, taller vegetation, and increased Sphagnum moss cover. Vegetation productivity, Sphagnum moss cover, and seasonal changes in photosynthetic capacity were negatively related to the abundances of terrestrial lichens. Inflated beta regression reliably estimated the abundance of terrestrial lichens (R2 = .74) which was interpolated on a map at fine resolution across a caribou range to support ecological conservation and reclamation. Results demonstrate that sampling for and simultaneously estimating both occupancy and abundance offer a powerful approach to improve statistical estimation and expand ecological inference in an applied setting. Learnings are broadly applicable to studying species that are rare, occupy narrow niches, or where the response variable is a proportion value containing zero or one, which is typical of vegetation cover data. 相似文献
998.
Describing and understanding behavioral responses to multiple stressors and multiple stimuli 下载免费PDF全文
Understanding the effects of environmental change on natural ecosystems is a major challenge, particularly when multiple stressors interact to produce unexpected “ecological surprises” in the form of complex, nonadditive effects that can amplify or reduce their individual effects. Animals often respond behaviorally to environmental change, and multiple stressors can have both population‐level and community‐level effects. However, the individual, not combined, effects of stressors on animal behavior are commonly studied. There is a need to understand how animals respond to the more complex combinations of stressors that occur in nature, which requires a systematic and rigorous approach to quantify the various potential behavioral responses to the independent and interactive effects of stressors. We illustrate a robust, systematic approach for understanding behavioral responses to multiple stressors based on integrating schemes used to quantitatively classify interactions in multiple‐stressor research and to qualitatively view interactions between multiple stimuli in behavioral experiments. We introduce and unify the two frameworks, highlighting their conceptual and methodological similarities, and use four case studies to demonstrate how this unification could improve our interpretation of interactions in behavioral experiments and guide efforts to manage the effects of multiple stressors. Our unified approach: (1) provides behavioral ecologists with a more rigorous and systematic way to quantify how animals respond to interactions between multiple stimuli, an important theoretical advance, (2) helps us better understand how animals behave when they encounter multiple, potentially interacting stressors, and (3) contributes more generally to the understanding of “ecological surprises” in multiple stressors research. 相似文献
999.
Postglacial recolonization shaped the genetic diversity of the winter moth (Operophtera brumata) in Europe 下载免费PDF全文
Jeremy C. Andersen Nathan P. Havill Adalgisa Caccone Joseph S. Elkinton 《Ecology and evolution》2017,7(10):3312-3323
Changes in climate conditions, particularly during the Quaternary climatic oscillations, have long been recognized to be important for shaping patterns of species diversity. For species residing in the western Palearctic, two commonly observed genetic patterns resulting from these cycles are as follows: (1) that the numbers and distributions of genetic lineages correspond with the use of geographically distinct glacial refugia and (2) that southern populations are generally more diverse than northern populations (the “southern richness, northern purity” paradigm). To determine whether these patterns hold true for the widespread pest species the winter moth (Operophtera brumata), we genotyped 699 individual winter moths collected from 15 Eurasian countries with 24 polymorphic microsatellite loci. We find strong evidence for the presence of two major genetic clusters that diverged ~18 to ~22 ka, with evidence that secondary contact (i.e., hybridization) resumed ~ 5 ka along a well‐established hybrid zone in Central Europe. This pattern supports the hypothesis that contemporary populations descend from populations that resided in distinct glacial refugia. However, unlike many previous studies of postglacial recolonization, we found no evidence for the “southern richness, northern purity” paradigm. We also find evidence for ongoing gene flow between populations in adjacent Eurasian countries, suggesting that long‐distance dispersal plays an important part in shaping winter moth genetic diversity. In addition, we find that this gene flow is predominantly in a west‐to‐east direction, suggesting that recently debated reports of cyclical outbreaks of winter moth spreading from east to west across Europe are not the result of dispersal. 相似文献
1000.
Chiara Merigliano Romina Burla Mattia La Torre Simona Del Giudice Hsiangling Teo Chong Wai Liew Alexandre Chojnowski Wah Ing Goh Yolanda Olmos Klizia Maccaroni Maria Giubettini Irene Chiolo Jeremy G. Carlton Domenico Raimondo Fiammetta Vernì Colin L. Stewart Daniela Rhodes Graham D. Wright Brian E. Burke Isabella Saggio 《PLoS genetics》2021,17(8)
To complete mitosis, the bridge that links the two daughter cells needs to be cleaved. This step is carried out by the endosomal sorting complex required for transport (ESCRT) machinery. AKTIP, a protein discovered to be associated with telomeres and the nuclear membrane in interphase cells, shares sequence similarities with the ESCRT I component TSG101. Here we present evidence that during mitosis AKTIP is part of the ESCRT machinery at the midbody. AKTIP interacts with the ESCRT I subunit VPS28 and forms a circular supra-structure at the midbody, in close proximity with TSG101 and VPS28 and adjacent to the members of the ESCRT III module CHMP2A, CHMP4B and IST1. Mechanistically, the recruitment of AKTIP is dependent on MKLP1 and independent of CEP55. AKTIP and TSG101 are needed together for the recruitment of the ESCRT III subunit CHMP4B and in parallel for the recruitment of IST1. Alone, the reduction of AKTIP impinges on IST1 and causes multinucleation. Our data altogether reveal that AKTIP is a component of the ESCRT I module and functions in the recruitment of ESCRT III components required for abscission. 相似文献