Optimal central-place foraging by beavers: Tree-size selection in relation to defensive chemicals of quaking aspen

At a newly occupied pond, beavers preferentially felled aspen smaller than 7.5 cm in diameter and selected against larger size classes. After one year of cutting, 10% of the aspen had been cut and 14% of the living aspen exhibited the juvenile growth form. A phenolic compound which may act as a deterrent to beavers was found in low concentrations in aspen bark, and there was no significant regression of relative concentration of this compound on tree diameter. At a pond which had been intermittently occupied by beavers for over 20 years, beavers selected against aspen smaller than 4.5 cm in diameter, and selected in favor of aspen larger than 19.5 cm in diameter. After more than 28 years of cutting at this site, 51% of the aspen had been cut and 49% of the living aspen were juvenileform. The phenolic compound was found in significantly higher concentrations in aspen bark than at the newly occupied site, and there was a significant negative regression of relative concentration on tree diameter. The results of this study show that responses to browsing by trees place constraints on the predictive value of standard energy-based optimal foraging models, and limitations on the use of such models. Future models should attempt to account for inducible responses of plants to damage and increases in concentrations of secondary metabolites through time.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47775/1/442_2004_Article_BF00379963.pd

Temporal stability of the rumen microbiota in beef cattle, and response to diet and supplements

Acknowledgements Sampling of ruminal digesta was carried out at Scotland’s Rural College (SRUC) by Laura Nicoll, Lesley Deans and Claire Broadbent. Sequencing using Illumina MiSeq was carried out by Edinburgh Genomics, The University of Edinburgh. Edinburgh Genomics is partly supported through core grants from NERC (R8/H10/56), MRC (MR/K001744/1) and BBSRC (BB/J004243/1). Data were processed using the Maxwell High Performance Computing Cluster of the University of Aberdeen IT Service (www.abdn.ac.uk/staffnet/research/hpc.php), provided by Dell Inc. and supported by Alces Software. Funding This work was funded by the Rural and Environment Science and Analytical Services Division (RESAS) of the Scottish Government as a collaborative HEI project between The University of Aberdeen, The Roslin Institute, and Scotland’s Rural College (SRUC). The funding body had no role in the design of the study or collection, analysis, or interpretation of data or in writing the manuscript.Peer reviewedPublisher PD