85 research outputs found
The Relative Influence of Competition and Prey Defenses on the Phenotypic Structure of Insectivorous Bat Ensembles in Southern Africa
Deterministic filters such as competition and prey defences should have a strong influence on the community structure of animals such as insectivorous bats that have life histories characterized by low fecundity, low predation risk, long life expectancy, and stable populations. We investigated the relative influence of these two deterministic filters on the phenotypic structure of insectivorous bat ensembles in southern Africa. We used null models to simulate the random phenotypic patterns expected in the absence of competition or prey defences and analysed the deviations of the observed phenotypic pattern from these expected random patterns. The phenotypic structure at local scales exhibited non-random patterns consistent with both competition and prey defense hypotheses. There was evidence that competition influenced body size distribution across ensembles. Competition also influenced wing and echolocation patterns in ensembles and in functional foraging groups with high species richness or abundance. At the same time, prey defense filters influenced echolocation patterns in two species-poor ensembles. Non-random patterns remained evident even after we removed the influence of body size from wing morphology and echolocation parameters taking phylogeny into account. However, abiotic filters such as geographic distribution ranges of small and large-bodied species, extinction risk, and the physics of flight and sound probably also interacted with biotic filters at local and/or regional scales to influence the community structure of sympatric bats in southern Africa. Future studies should investigate alternative parameters that define bat community structure such as diet and abundance to better determine the influence of competition and prey defences on the structure of insectivorous bat ensembles in southern Africa
Large-order NSPT for lattice gauge theories with fermions:the plaquette in massless QCD
Numerical Stochastic Perturbation Theory (NSPT) allows for perturbative
computations in quantum field theory. We present an implementation of NSPT that
yields results for high orders in the perturbative expansion of lattice gauge
theories coupled to fermions. The zero-momentum mode is removed by imposing
twisted boundary conditions; in turn, twisted boundary conditions require us to
introduce a smell degree of freedom in order to include fermions in the
fundamental representation. As a first application, we compute the critical
mass of two flavours of Wilson fermions up to order in a
gauge theory. We also implement, for the first time,
staggered fermions in NSPT. The residual chiral symmetry of staggered fermions
protects the theory from an additive mass renormalisation. We compute the
perturbative expansion of the plaquette with two flavours of massless staggered
fermions up to order in a gauge theory, and
investigate the renormalon behaviour of such series. We are able to subtract
the power divergence in the Operator Product Expansion (OPE) for the plaquette
and estimate the gluon condensate in massless QCD. Our results confirm that
NSPT provides a viable way to probe systematically the asymptotic behaviour of
perturbative series in QCD and, eventually, gauge theories with fermions in
higher representations.Comment: 49 pages, 28 figures. Revised version, to be published in EPJC. Some
references added, typos corrected, and improved discussion on finite-volume
effect
Prefrontal Cortex Based Sex Differences in Tinnitus Perception: Same Tinnitus Intensity, Same Tinnitus Distress, Different Mood
BACKGROUND: Tinnitus refers to auditory phantom sensation. It is estimated that for 2% of the population this auditory phantom percept severely affects the quality of life, due to tinnitus related distress. Although the overall distress levels do not differ between sexes in tinnitus, females are more influenced by distress than males. Typically, pain, sleep, and depression are perceived as significantly more severe by female tinnitus patients. Studies on gender differences in emotional regulation indicate that females with high depressive symptoms show greater attention to emotion, and use less anti-rumination emotional repair strategies than males. METHODOLOGY: The objective of this study was to verify whether the activity and connectivity of the resting brain is different for male and female tinnitus patients using resting-state EEG. CONCLUSIONS: Females had a higher mean score than male tinnitus patients on the BDI-II. Female tinnitus patients differ from male tinnitus patients in the orbitofrontal cortex (OFC) extending to the frontopolar cortex in beta1 and beta2. The OFC is important for emotional processing of sounds. Increased functional alpha connectivity is found between the OFC, insula, subgenual anterior cingulate (sgACC), parahippocampal (PHC) areas and the auditory cortex in females. Our data suggest increased functional connectivity that binds tinnitus-related auditory cortex activity to auditory emotion-related areas via the PHC-sgACC connections resulting in a more depressive state even though the tinnitus intensity and tinnitus-related distress are not different from men. Comparing male tinnitus patients to a control group of males significant differences could be found for beta3 in the posterior cingulate cortex (PCC). The PCC might be related to cognitive and memory-related aspects of the tinnitus percept. Our results propose that sex influences in tinnitus research cannot be ignored and should be taken into account in functional imaging studies related to tinnitus
Correlated Genetic and Ecological Diversification in a Widespread Southern African Horseshoe Bat
The analysis of molecular data within a historical biogeographical framework, coupled with ecological characteristics can provide insight into the processes driving diversification. Here we assess the genetic and ecological diversity within a widespread horseshoe bat Rhinolophus clivosus sensu lato with specific emphasis on the southern African representatives which, although not currently recognized, were previously described as a separate species R. geoffroyi comprising four subspecies. Sequence divergence estimates of the mtDNA control region show that the southern African representatives of R. clivosus s.l. are as distinct from samples further north in Africa than they are from R. ferrumequinum, the sister-species to R. clivosus. Within South Africa, five genetically supported geographic groups exist and these groups are corroborated by echolocation and wing morphology data. The groups loosely correspond to the distributions of the previously defined subspecies and Maxent modelling shows a strong correlation between the detected groups and ecoregions. Based on molecular clock calibrations, it is evident that climatic cycling and related vegetation changes during the Quaternary may have facilitated diversification both genetically and ecologically
Brachytrupes acuminipennis Simeu-Noutchom & Heller & Nyobe & Kekeunou 2023, stat. rev.
Species <i>Brachytrupes acuminipennis</i> (Fairmaire, 1858) stat. rev. (Table 4) <p> <i>Gryllus acuminipennis</i> Fairmaire, 1858: p. 257</p> <p> <b>Type material:</b> unspecified; central Africa, Gabon.</p> <p> <b>Description</b> (Fairmaire 1858) Reddish, with a brown tint on the front of the head, the top and sides of the prothorax, lighter on the tegmina; hind femur thighs with short brown hatching, forming a longitudinal band above the middle, a brown spot before the end. Antennae longer than the body, reaching the end of the tegmina; forehead having, between the antennae, a slight impression with raised edges. Widely sinuate prothorax in the middle of the anterior border, on the disc a wide furrowed impression in the middle. Tegmina fairly long, acuminate, with strong veins. The four forelegs rather short and fairly robust, finely hairy; large and very robust hind femora, thigh much longer than tibia, very thick, sharp and somewhat leafy below; tibia armed, outside, with a double row of spins, and at the extremity with four very strong mobile spurs; first segment of hind tarsi almost twice as long as third, spiny above; the second almost hidden, very small; abdominal appendices half as long as the abdomen.</p> <p> <b>Distribution:</b> Gabon</p>Published as part of <i>Simeu-Noutchom, Alain, Heller, Klaus-Gerhard, Nyobe, Philene Corinne Aude Um & Kekeunou, Sevilor, 2023, Taxonomy review of the genus Brachytrupes (Orthoptera: Gryllidae) with the description of a new species and key to the species, pp. 373-388 in Zootaxa 5336 (3)</i> on pages 381-382, DOI: 10.11646/zootaxa.5336.3.4, <a href="http://zenodo.org/record/8281577">http://zenodo.org/record/8281577</a>
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