Developing common protocols to measure tundra herbivory across spatial scales

Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied, and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot- and site-level protocols were tested in the field during summers 2014–2015 at 11 sites, nine of them consisting of warming experimental plots included in the International Tundra Experiment (ITEX). The study area protocols were assessed during 2014–2018 at 24 study areas across the Arctic. Our protocols provide comparable and easy to implement methods for assessing the intensity of invertebrate herbivory within ITEX plots and for characterizing vertebrate herbivore communities at larger spatial scales. We discuss methodological constraints and make recommendations for how these protocols can be used and how sampling effort can be optimized to obtain comparable estimates of herbivory, both at ITEX sites and at large landscape scales. The application of these protocols across the tundra biome will allow characterizing and comparing herbivore communities across tundra sites and at ecologically relevant spatial scales, providing an important step towards a better understanding of tundra ecosystem responses to large-scale environmental change

Environmental barriers to sociality in an obligate eusocial sweat bee

This is the final version of the article. Available from Springer Verlag via the DOI in this record.All data generated or analysed during this study are included in this published article and its supplementary materials.Understanding the ecological and environmental contexts in which eusociality can evolve is fundamental to elucidating its evolutionary origins. A sufficiently long active season is postulated to have been a key factor facilitating the transition to eusociality. Many primitively eusocial species exhibit an annual life cycle, which is thought to preclude the expression of eusociality where the active season is too short to produce successive worker and reproductive broods. However, few studies have attempted to test this idea experimentally. We investigated environmental constraints on the expression of eusociality in the obligate primitively eusocial sweat bee Lasioglossum malachurum, by transplanting nest foundresses from the south to the far north of the United Kingdom, far beyond the natural range of L. malachurum. We show that transplanted bees can exhibit eusociality, but that the short length of the season and harsher environmental conditions could preclude its successful expression. In one year, when foundresses were transplanted only after provisioning first brood (B1) offspring, workers emerged in the north and provisioned a second brood (B2) of reproductives. In another year, when foundresses were transplanted prior to B1 being provisioned, they were just as likely to initiate nesting and provisioned just as many B1 cells as foundresses in the south. However, the life cycle was delayed by approximately 7 weeks and nests suffered 100% B1 mortality. Our results suggest that short season length together with poor weather conditions represent an environmental barrier to the evolution and expression of eusociality in sweat bees.This work formed part of a studentship (1119965) awarded to PJD funded by the Natural Environment Research Council and the University of Sussex, supervised by JF

A REVIEW ON DIFFERENT TECHNIQUES USED IN DESIGN OF ULTRA WIDEBAND SLOT ANTENNA FOR IMPROVEMENT OF VARIOUS PARAMETER

An Ultra-Wideband patch antenna plays a major role in communications. This article deals with the broad review of Micro strip patch antenna design parameters such as Reflection Coeffient,VSWR,Impedance,Gain,Effiency,Radiation Pattern etc. various slots for different applications i.e. designs, development of output factors etc. In this modern world a dual band and triple band antenna with notch characteristics plays a vital role in wireless communications like UWB, WLAN, WiMAX etc. In this paper we study about the dual band and triple band characteristics and applications. The good impedance bandwidth, efficiency, Radiation pattern, VSWR can be improved by using the different slots, truncating corner of ground Plane ,feeding techniques, resonance frequency, and dielectric substrate

Mechanistic model identifies increasing light availability due to sea ice reductions as cause for increasing macroalgae cover in the Arctic

In the Arctic, rising seawater temperatures and increasing underwater light caused by reductions in sea ice cover are expected to change the structure of arctic marine communities. Substantial, sometimes sudden, increases in macroalgal productivity and biomass have already been observed in arctic rocky bottom communities. These macroalgal responses have been attributed to increasing temperature and light, but the relative importance of the suggested drivers of change has not yet been assessed. In this study, we used a mechanistic competition model to unravel the effects of temperature and light on benthic community structure and algae dominance, focusing on key algae species: red calcareous algae and macroalgal fronds. We find that light is the primary driver of increases in macroalgal coverage, whereas increased seawater temperature plays a secondary role. Shifts leading to macroalgae dominated communities may be mediated by competitive interactions, and are likely due to three light-related processes: earlier sea ice break-out at high latitudes can result in an exponential increase in the cumulative amount of light that enters the water column during a year; threshold effect in light requirements for algal growth; and light requirements of calcareous algae being substantially lower than those of macroalgae. With continued warming, our modeling results suggest that reduced sea ice coverage and increased light availability will favor dominance of macroalgae, which due to their key ecological role are expected to alter the structure and functioning of arctic rocky bottom ecosystems