Longevity of companion dog breeds: those at risk from early death

The companion dog is one of the most phenotypically diverse species. Variability between breeds extends not only to morphology and aspects of behaviour, but also to longevity. Despite this fact, little research has been devoted to assessing variation in life expectancy between breeds or evaluating the potential for phylogenetic characterisation of longevity. Using a dataset of 584,734 unique dogs located within the UK, including 284,734 deceased, we present variation in longevity estimates within the following: parental lineage (purebred = 1 breed, crossbred ≥ 2 breeds), breed (n = 155), body size (large, medium, small), sex (male, female) and cephalic index (brachycephalic, mesocephalic, dolichocephalic). Survival estimates were then partitioned amongst phylogenetic clades: providing evidence that canine evolutionary history (via domestication and associated artificial selection) is associated with breed lifespan. This information provides evidence to inform discussions regarding pedigree health, whilst helping current/prospective owners, breeders, policy makers, funding bodies and welfare organisations improve decision making regarding canine welfare

Quasar Sightline and Galaxy Evolution (QSAGE) - III. The mass-metallicity and fundamental metallicity relation of z ≈ 2.2 galaxies

We present analysis of the mass-metallicity relation (MZR) for a sample of 67 [O iii]-selected star-forming (SF) galaxies at a redshift range of z = 1.99-2.32 (zmed = 2.16) using Hubble Space Telescope Wide Field Camera 3 grism spectroscopy from the Quasar Sightline and Galaxy Evolution survey. Metallicities were determined using empirical gas-phase metallicity calibrations based on the strong emission lines [O ii]3727, 3729, [O iii]4959, 5007 and Hβ. SF galaxies were identified, and distinguished from active-galactic nuclei, via Mass-Excitation diagrams. Using z ∼0 metallicity calibrations, we observe a negative offset in the z = 2.2 MZR of ≈-0.51 dex in metallicity when compared to locally derived relationships, in agreement with previous literature analysis. A similar offset of ≈-0.46 dex in metallicity is found when using empirical metallicity calibrations that are suitable out to z ∼5, though our z = 2.2 MZR, in this case, has a shallower slope. We find agreement between our MZR and those predicted from various galaxy evolution models and simulations. Additionally, we explore the extended fundamental metallicity relation (FMR) which includes an additional dependence on star formation rate. Our results consistently support the existence of the FMR, as well as revealing an offset of 0.28 ± 0.04 dex in metallicity compared to locally derived relationships, consistent with previous studies at similar redshifts. We interpret the negative correlation with SFR at fixed mass, inferred from an FMR existing for our sample, as being caused by the efficient accretion of metal-poor gas fuelling SFR at cosmic noon

Within- and Among-Population Variation in Chytridiomycosis-Induced Mortality in the Toad Alytes obstetricans

Background Chytridiomycosis is a fungal disease linked to local and global extinctions of amphibians. Susceptibility to chytridiomycosis varies greatly between amphibian species, but little is known about between- and within-population variability. However, this kind of variability is the basis for the evolution of tolerance and resistance evolution to disease. Methodology/Principal Findings In a common garden experiment, we measured mortality after metamorphosis of Alytes obstetricans naturally infected with Batrachochytrium dendrobatidis. Mortality rates differed significantly among populations and ranged from 27 to 90%. Within populations, mortality strongly depended on mass at and time through metamorphosis. Conclusions/Significance Although we cannot rule out that the differences observed resulted from differences in skin microbiota, different pathogen strains or environmental effects experienced by the host or the pathogen prior to the start of the experiment, we argue that genetic differences between populations are a likely source of at least part of this variation. To our knowledge, this is the first study showing differences in survival between and within populations under constant laboratory conditions. Assuming that some of this intraspecific variation has a genetic basis, this may suggest that there is the potential for the evolution of resistance or tolerance, which might allow population persistence

Snout Shape in Extant Ruminants

Copyright: © 2014 Tennant, MacLeod. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. [4.0 license]. The attached file is the published version of the article

Multiple Determinants of Whole and Regional Brain Volume among Terrestrial Carnivorans

Mammalian brain volumes vary considerably, even after controlling for body size. Although several hypotheses have been proposed to explain this variation, most research in mammals on the evolution of encephalization has focused on primates, leaving the generality of these explanations uncertain. Furthermore, much research still addresses only one hypothesis at a time, despite the demonstrated importance of considering multiple factors simultaneously. We used phylogenetic comparative methods to investigate simultaneously the importance of several factors previously hypothesized to be important in neural evolution among mammalian carnivores, including social complexity, forelimb use, home range size, diet, life history, phylogeny, and recent evolutionary changes in body size. We also tested hypotheses suggesting roles for these variables in determining the relative volume of four brain regions measured using computed tomography. Our data suggest that, in contrast to brain size in primates, carnivoran brain size may lag behind body size over evolutionary time. Moreover, carnivore species that primarily consume vertebrates have the largest brains. Although we found no support for a role of social complexity in overall encephalization, relative cerebrum volume correlated positively with sociality. Finally, our results support negative relationships among different brain regions after accounting for overall endocranial volume, suggesting that increased size of one brain regions is often accompanied by reduced size in other regions rather than overall brain expansion

Elevational Distribution and Extinction Risk in Birds

Mountainous regions are hotspots of terrestrial biodiversity. Unlike islands, which have been the focus of extensive research on extinction dynamics, fewer studies have examined mountain ranges even though they face increasing threats from human pressures – notably habitat conversion and climate change. Limits to the taxonomic and geographical extent and resolution of previously available information have precluded an explicit assessment of the relative role of elevational distribution in determining extinction risk. We use a new global species-level avian database to quantify the influence of elevational distribution (range, maximum and midpoint) on extinction risk in birds at the global scale. We also tested this relationship within biogeographic realms, higher taxonomic levels, and across phylogenetic contrasts. Potential confounding variables (i.e. phylogenetic, distributional, morphological, life history and niche breadth) were also tested and controlled for. We show that the three measures of elevational distribution are strong negative predictors of avian extinction risk, with elevational range comparable and complementary to that of geographical range size. Extinction risk was also found to be positively associated with body weight, development and adult survival, but negatively associated with reproduction and niche breadth. The robust and consistent findings from this study demonstrate the importance of elevational distribution as a key driver of variation in extinction dynamics in birds. Our results also highlight elevational distribution as a missing criterion in current schemes for quantifying extinction risk and setting species conservation priorities in birds. Further research is recommended to test for generality across non-avian taxa, which will require an advance in our knowledge of species’ current elevational ranges and increased efforts to digitise and centralise such data

Complex body size trends in the evolution of sloths (Xenarthra: Pilosa)

Background Extant sloths present an evolutionary conundrum in that the two living genera are superficially similar (small-bodied, folivorous, arboreal) but diverged from one another approximately 30 million years ago and are phylogenetically separated by a radiation of medium to massive, mainly ground-dwelling, taxa. Indeed, the species in the two living genera are among the smallest, and perhaps most unusual, of the 50+ known sloth species, and must have independently and convergently evolved small size and arboreality. In order to accurately reconstruct sloth evolution, it is critical to incorporate their extinct diversity in analyses. Here, we used a dataset of 57 species of living and fossil sloths to examine changes in body mass mean and variance through their evolution, employing a general time-variable model that allows for analysis of evolutionary trends in continuous characters within clades lacking fully-resolved phylogenies, such as sloths. Results Our analyses supported eight models, all of which partition sloths into multiple subgroups, suggesting distinct modes of body size evolution among the major sloth lineages. Model-averaged parameter values supported trended walks in most clades, with estimated rates of body mass change ranging as high as 126 kg/million years for the giant ground sloth clades Megatheriidae and Nothrotheriidae. Inclusion of living sloth species in the analyses weakened reconstructed rates for their respective groups, with estimated rates for Megalonychidae (large to giant ground sloths and the extant two-toed sloth) were four times higher when the extant genus Choloepus was excluded. Conclusions Analyses based on extant taxa alone have the potential to oversimplify or misidentify macroevolutionary patterns. This study demonstrates the impact that integration of data from the fossil record can have on reconstructions of character evolution and establishes that body size evolution in sloths was complex, but dominated by trended walks towards the enormous sizes exhibited in some recently extinct forms

Overview of the DESI Legacy Imaging Surveys

The DESI Legacy Imaging Surveys (http://legacysurvey.org/) are a combination of three public projects (the Dark Energy Camera Legacy Survey, the Beijing–Arizona Sky Survey, and the Mayall z-band Legacy Survey) that will jointly image ≈14,000 deg2 of the extragalactic sky visible from the northern hemisphere in three optical bands (g, r, and z) using telescopes at the Kitt Peak National Observatory and the Cerro Tololo Inter-American Observatory. The combined survey footprint is split into two contiguous areas by the Galactic plane. The optical imaging is conducted using a unique strategy of dynamically adjusting the exposure times and pointing selection during observing that results in a survey of nearly uniform depth. In addition to calibrated images, the project is delivering a catalog, constructed by using a probabilistic inference-based approach to estimate source shapes and brightnesses. The catalog includes photometry from the grz optical bands and from four mid-infrared bands (at 3.4, 4.6, 12, and 22 μm) observed by the Wide-field Infrared Survey Explorer satellite during its full operational lifetime. The project plans two public data releases each year. All the software used to generate the catalogs is also released with the data. This paper provides an overview of the Legacy Surveys project

4MOST: Project overview and information for the First Call for Proposals

We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs ($R = \lambda/\Delta\lambda \sim 6500$), and 812 fibres transferring light to the high-resolution spectrograph ($R \sim 20\,000$). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations

The nature of sub-millimetre galaxies I: a comparison of AGN and star-forming galaxy SED fits

High-redshift sub-millimetre galaxies (SMGs) are usually assumed to be powered by star formation. However, it has been clear for some time that >20 per cent of such sourcesbrighter than ≈3 mJy host quasars. Here, we analyse a complete sample of 12 sub-mm LABOCA/ALMA 870-μm sources in the centre of the William Herschel Deep Field (WHDF) with multiwavelength data available from the X-ray to the radio bands. Previously, two sources were identified as X-ray-absorbed quasars at z = 1.32 and z = 2.12. By comparing their spectral energy distributions (SEDs) with unabsorbed quasars in the same field, we confirm that they are dust reddened although at a level significantly lower than implied by their X-ray absorption. Then, we compare the SEDs of all the sources to dust-reddened AGN and star-forming galaxy models. This optical/NIR comparison combined with Spitzer MIR colours and faint Chandra X-ray detections shows that 7/12 SMGs are best fitted with an obscured quasar model, a further 3/12 show no preference between AGN and star-forming templates, leaving only a z = 0.046 spiral galaxy and one unidentified source. So in our complete sample, the majority (10/12) of bright SMGs are at least as likely to fit an AGN as a star-forming galaxy template, although no claim is made to rule out the latter as SMG power sources. We then suggest modifications to a previous SMG number count model and conclude that obscured AGN in SMGs may still provide the dominant contribution to both the hard X-ray and sub-millimetre backgrounds