The hairy–downy game revisited: an empirical test of the interspecific social dominance mimicry hypothesis

© 2018 The Association for the Study of Animal Behaviour. Understanding the emergence and persistence of convergent phenotypes is the subject of considerable debate. Species may converge on nearly identical phenotypes for a variety of reasons, including occupying similar environments, exhibiting similar foraging ecologies, and for signalling reasons such as mimicry. Interspecific social dominance mimicry (ISDM) is a hypothesis that states that socially subordinate species evolve a phenotype mimicking a dominant species so as to accrue resources and avoid aggression. A recently proposed test case for this phenomenon asserts that downy woodpeckers, Picoides pubescens, evolved mimetic plumage to avoid attacks from hairy woodpeckers, Picoides villosus. We examined this claim with a large behavioural data set collected by citizen scientists. We employed phylogenetic methods and simulations to test whether downy woodpeckers avoid aggression, and whether downy woodpeckers are more dominant than expected based on body mass. Contrary to the expectations of ISDM, we found that downy woodpeckers were markedly more often the target of hairy woodpecker attacks than expected based on their relative abundances. Our empirical data thus offers no support for the strict ISDM hypothesis as an explanation for downy–hairy woodpecker plumage convergence. However, downy woodpeckers are slightly more dominant than expected based on their body mass, albeit not significantly so. Our data therefore lend weight to previous suggestions that the benefits of mimicry potentially accrue from third-party species mistaking the mimic for the model, rather than the model mistaking the mimic for another model

Evidence for longitudinal migration by a “sedentary” Brazilian flycatcher, the Ash-throated Casiornis

The digitalization of museum collections and concurrent increase in citizen-scienceinitiatives is ushering in an era of unprecedented availability of primary biodiversity data. These changespermit a reappraisal of phenological patterns of tropical species. I examined spatio-temporal variation in thedistribution patterns of an ostensibly sedentary endemic Brazilian flycatcher, the Ash-throated Casiornis(Casiornis fuscus), using both specimen data from museums and sighting records and rich media data fromcitizen-science initiatives. I found compelling evidence for partial intratropical longitudinal migration toAmazonia and the Cerrado biomes from the species’ core range in the semi-desert Caatinga biome andadjacent ecotones. These records from outside of the Caatinga were distributed during the height of the dryseason from April to October, although the Caatinga is not entirely vacated at this time. This pattern ofpartial migration leads to a doubling of the distributional range of Ash-throated Casiornises and stronglysuggests that the species is a breeding near-endemic of the Caatinga biome. This pattern was potentiallypreviously not apparent because of significant biases in specimen collection between biomes, giving a falsesense of abundance in the Brazilian Amazon

Widespread forest vertebrate extinctions induced by a mega hydroelectric dam in lowland Amazonia

Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, underconstruction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments

Search for Charged Higgs Bosons in e+e- Collisions at \sqrt{s} = 189 GeV

A search for pair-produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.4 pb^-1. Higgs decays into a charm and a strange quark or into a tau lepton and its associated neutrino are considered. The observed events are consistent with the expectations from Standard Model background processes. A lower limit of 65.5 GeV on the charged Higgs mass is derived at 95 % confidence level, independent of the decay branching ratio Br(H^{+/-} -> tau nu)

Study of Bc+B_c^+ decays to the K+K−π+K^+K^-\pi^+ final state and evidence for the decay Bc+→χc0π+B_c^+\to\chi_{c0}\pi^+

A study of $B_c^+\to K^+K^-\pi^+$ decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 $\mathrm{fb}^{-1}$ collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of $7$ and $8$ TeV. Evidence for the decay $B_c^+\to\chi_{c0}(\to K^+K^-)\pi^+$ is reported with a significance of 4.0 standard deviations, resulting in the measurement of $\frac{\sigma(B_c^+)}{\sigma(B^+)}\times\mathcal{B}(B_c^+\to\chi_{c0}\pi^+)$ to be $(9.8^{+3.4}_{-3.0}(\mathrm{stat})\pm 0.8(\mathrm{syst}))\times 10^{-6}$. Here $\mathcal{B}$ denotes a branching fraction while $\sigma(B_c^+)$ and $\sigma(B^+)$ are the production cross-sections for $B_c^+$ and $B^+$ mesons. An indication of $\bar b c$ weak annihilation is found for the region $m(K^-\pi^+)<1.834\mathrm{\,Ge\kern -0.1em V\!/}c^2$, with a significance of 2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html, link to supplemental material inserted in the reference

Endomicroscopic and transcriptomic analysis of impaired barrier function and malabsorption in environmental enteropathy

Introduction: Environmental enteropathy (EE) is associated with growth failure, micronutrient malabsorption and impaired responses to oral vaccines. We set out to define cellular mechanisms of impaired barrier function in EE and explore protective mechanisms. Methods: We studied 49 adults with environmental enteropathy in Lusaka, Zambia using confocal laser endomicroscopy (CLE); histology, immunohistochemistry and mRNA sequencing of small intestinal biopsies; and correlated these with plasma lipopolysaccharide (LPS) and a zinc uptake test. Results: CLE images (median 134 for each study) showed virtually ubiquitous small intestinal damage. Epithelial defects, imaged by histology and claudin 4 immunostaining, were predominantly seen at the tips of villi and corresponded with leakage imaged in vivo by CLE. In multivariate analysis, circulating log-transformed LPS was correlated with cell shedding events (β = 0.83; P = 0.035) and with serum glucagon-like peptide-2 (β = -0.13; P = 0.007). Zinc uptake from a test dose of 25mg was attenuated in 30/47 (64%) individuals and in multivariate analysis was reduced by HIV, but positively correlated with GLP-2 (β = 2.72; P = 0.03). There was a U-shaped relationship between circulating LPS and villus surface area. Transcriptomic analysis identified 23 differentially expressed genes in severe enteropathy, including protective peptides and proteins. Conclusions: Confocal endomicroscopy, claudin 4 immunostaining and histology identify epithelial defects which are probably sites of bacterial translocation, in the presence of which increased epithelial surface area increases the burden of translocation. GLP 2 and other protective peptides may play an important role in mucosal protection in EE

On dendrograms, ordinations and functional spaces: Methodo-logical choices or pitfalls?

A number of concerns persist regarding (i) how functional spaces should be quantified, (ii) how phylogenetic richness should be calculated, (iii) and how functional beta diversity should be calculated. Because all current methods have their shortcomings we think that analytical choices are as much a matter of knowing the limitations of the data and knowing the working hypothesis. Only then can one follow their personal choice, weighing up the shortcomings of different methods that, at the end of the day, usually produce qualitatively similar results

Investigating mechanisms underpinning the detrimental impact of a high-fat diet in the developing and adult hypermuscular myostatin null mouse

Background: Obese adults are prone to develop metabolic and cardiovascular diseases. Furthermore, over-weight expectant mothers give birth to large babies who also have increased likelihood of developing metabolic and cardiovascular diseases. Fundamental advancements to better understand the pathophysiology of obesity are critical in the development of anti-obesity therapies not only for this but also future generations. Skeletal muscle plays a major role in fat metabolism and much work has focused in promoting this activity in order to control the development of obesity. Research has evaluated myostatin inhibition as a strategy to prevent the development of obesity and concluded in some cases that it offers a protective mechanism against a high-fat diet. Results: We hypothesised that myostatin inhibition should protect not only the mother but also its developing foetus from the detrimental effects of a high-fat diet. Unexpectedly, we found muscle development was attenuated in the foetus of myostatin null mice raised on a high-fat diet. We therefore re-examined the effect of the high-fat diet on adults and found myostatin null mice were more susceptible to diet-induced obesity through a mechanism involving impairment of inter-organ fat utilization. Conclusions: Loss of myostatin alters fatty acid uptake and oxidation in skeletal muscle and liver. We show that abnormally high metabolic activity of fat in myostatin null mice is decreased by a high-fat diet resulting in excessive adipose deposition and lipotoxicity. Collectively, our genetic loss-of-function studies offer an explanation of the lean phenotype displayed by a host of animals lacking myostatin signalling. Keywords: Muscle, Obesity, High-fat diet, Metabolism, Myostati