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101.
Global patterns of Rhododendron diversity: The role of evolutionary time and diversification rates
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Nawal Shrestha Zhiheng Wang Xiangyan Su Xiaoting Xu Lisha Lyu Yunpeng Liu Dimitar Dimitrov Jonathan D. Kennedy Qinggang Wang Zhiyao Tang Xiaojuan Feng 《Global Ecology and Biogeography》2018,27(8):913-924
Aim
Understanding the evolution of the latitudinal diversity gradient (i.e. increase in species diversity towards the tropics) is a prominent issue in ecology and biogeography. Disentangling the relative contributions of environment and evolutionary history in shaping this gradient remains a major challenge because their relative importance has been found to vary across regions and taxa. Here, using the global distributions and a molecular phylogeny of Rhododendron, one of the largest genera of flowering plants, we aim to compare the relative contributions of contemporary environment, evolutionary time and diversification rates in generating extant species diversity patterns.Location
Global.Time period
Undefined.Major taxa studied
Rhododendron.Methods
We compiled the global distributions of all Rhododendron species, and constructed a dated molecular phylogeny using nine chloroplast genes and seven nuclear regions. By integrating these two datasets, we estimated the temporal trends of Rhododendron diversification, and explored the global patterns of its species diversity, net diversification rates, and species ages. Next, we reconstructed the geographical ancestral area of the clade. Finally, we compared the relative contribution of contemporary environment, time‐for‐speciation, and diversification rates on the species diversity pattern of Rhododendron.Results
In contrast to the predictions of the time‐for‐speciation hypothesis, we found that although Rhododendron originated at a temperate latitude, its contemporary species diversity is highest in the tropics/subtropics, suggesting an into‐the‐tropics colonization for this genus. We found that the elevated diversification induced by heterogeneous environmental conditions in the tropics/subtropics shapes the global pattern of Rhododendron diversity.Main conclusions
Our findings support tropical and subtropical mountains as not only biodiversity and endemism hotspots, but also as cradles for the diversification of Rhododendron. Our study emphasizes the need of unifying ecological and evolutionary approaches in order to gain comprehensive understanding of the mechanisms underlying the global patterns of plant diversity. 相似文献102.
103.
104.
RENÉ van der WAL SOFIE SJÖGERSTEN† SARAH J. WOODIN† ELISABETH J. COOPER‡ INGIBJÖRG S. JÓNSDÓTTIR‡ DRIES KUIJPER§ TONY A. D. FOX¶ A. D. HUISKES 《Global Change Biology》2007,13(2):539-545
Tundra ecosystems are widely recognized as precious areas and globally important carbon (C) sinks, yet our understanding of potential threats to these habitats and their large soil C store is limited. Land‐use changes and conservation measures in temperate regions have led to a dramatic expansion of arctic‐breeding geese, making them important herbivores of high‐latitude systems. In field experiments conducted in high‐Arctic Spitsbergen, Svalbard, we demonstrate that a brief period of early season belowground foraging by pink‐footed geese is sufficient to strongly reduce C sink strength and soil C stocks of arctic tundra. Mechanisms are suggested whereby vegetation disruption due to repeated use of grubbed areas opens the soil organic layer to erosion and will thus lead to progressive C loss. Our study shows, for the first time, that increases in goose abundance through land‐use change and conservation measures in temperate climes can dramatically affect the C balance of arctic tundra. 相似文献
105.
UWE MOHR JÜRG LANGE THOMAS BOLLER RES WIEMKEN & REGINA VÖGELI-LANGE 《The New phytologist》1998,138(4):589-598
106.
The results of a detailed morphological and morphometrical chromosome analysis of Rana camerani (2n = 26) are described. It was established that the karyotype of this species consisted of three homologous pairs of large metacentrics, two homologous pairs of large submetacentrics, three homologous pairs of small metacentrics, two homologous pairs of small submetacentrics, and three homologous pairs of small subtelocentrics. Morphologically discernible sex chromosomes were not found. The similarity and peculiarities in the R. camerani karyotype and those of R. temporaria, R. dalmatina and R. graeca are discussed. This comparative karyotype analysis has suggested the possibility for developing a general chromosomal formula, by means of which these 26-chromosome species could be characterized. 相似文献
107.
We have used a new light footprinting technique to study the interaction of histone H1(0) and a deletion mutant delta CH1(0) (lacking H1(0) COOH-terminal domain) with a synthetic four-way junction DNA. This technique is based on a single 5-ns UV laser pulse and has the ability to map protein-DNA interactions within unperturbed complexes at time scales far faster than molecular rearrangements. We found both H1(0) and delta CH1(0) to affect the photoreactivity of specific guanine residues located on the central part of four-way junction DNA. These observations demonstrate specific recognition of H1(0) for the central domain of four-way junction DNA. In addition, histone H1(0) decreases the photoreactivity of selected guanines located some distance from the crossover, indicating specific involvement of the H1(0) COOH-terminal tail with this region. Immunofractionation of delta CH1(0)-four-way DNA junction complexes with monoclonal anti-H1 antibody combined with the UV laser footprinting method demonstrated the existence of two types of delta CH1(0)-four-way DNA junction complexes. 相似文献
108.
The spider tree of life: phylogeny of Araneae based on target‐gene analyses from an extensive taxon sampling
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Ward C. Wheeler Jonathan A. Coddington Louise M. Crowley Dimitar Dimitrov Pablo A. Goloboff Charles E. Griswold Gustavo Hormiga Lorenzo Prendini Martín J. Ramírez Petra Sierwald Lina Almeida‐Silva Fernando Alvarez‐Padilla Miquel A. Arnedo Ligia R. Benavides Silva Suresh P. Benjamin Jason E. Bond Cristian J. Grismado Emile Hasan Marshal Hedin Matías A. Izquierdo Facundo M. Labarque Joel Ledford Lara Lopardo Wayne P. Maddison Jeremy A. Miller Luis N. Piacentini Norman I. Platnick Daniele Polotow Diana Silva‐Dávila Nikolaj Scharff Tamás Szűts Darrell Ubick Cor J. Vink Hannah M. Wood Junxia Zhang 《Cladistics : the international journal of the Willi Hennig Society》2017,33(6):574-616
109.
JÜRG ENKERLI ROLAND K
LLIKER SIEGFRIED KELLER FRANCO WIDMER 《Molecular ecology resources》2005,5(2):384-386
Fourteen polymorphic microsatellite markers were isolated from the entomopathogenic fungus, Metarhizium anisopliae, based on enriched genomic libraries. In order to assess allelic variability, the microsatellite loci were analysed in a collection of 34 isolates sampled from across Switzerland. The number of detected alleles in 14 loci ranged from two to eight and expected heterozygosity from 0.265 to 0.808. Because of the high expected heterozygosity, the 14 microsatellite loci are very useful for ecological studies and analysis of population diversity, and to identifying, monitoring, and tracking M. anisopliae strains applied as biological control agents. 相似文献
110.
G V Dimitrov T I Arabadzhiev J-Y Hogrel N A Dimitrova 《Journal of electromyography and kinesiology》2008,18(1):35-43
Capabilities of amplitude and spectral methods for information extraction from interference EMG signals were assessed through simulation and preliminary experiment. Muscle was composed of 4 types of motor units (MUs). Different hypotheses on changes in firing frequency of individual MUs, intracellular action potential (IAP) and muscle fibre propagation velocity (MFPV) during fatigue were analyzed. It was found that changes in amplitude characteristics of interference signals (root mean square, RMS, or integrated rectified value, IEMG) detected by intramuscular and surface electrodes differed. RMS and IEMG of surface detected interference signals could increase even under MU firing rate reduction and without MU synchronisation. IAP profile lengthening can affect amplitude characteristics more significantly than MU firing frequency. Thus, an increase of interference EMG amplitude is unreliable to reflect changes in the neural drive. The ratio between EMG amplitude and contraction response can hardly characterise the so-called 'neuromuscular efficiency'. The recently proposed spectral fatigue indices can be used for quantification of interference EMG signals. The indices are practically insensitive to MU firing frequency. IAP profile lengthening and decrease in MFPV enhanced the index value, while recruitment of fast fatigable MUs reduced it. Sensitivity of the indices was higher than that of indices traditionally used. 相似文献