Aliens will provide: avian responses to a new temporal resource offered by ornithocorous exotic shrubs

Oecologia - Frugivorous birds are able to track spatiotemporal changes in fruit availability. Food resource fluctuations, characteristic of seasonal environments, can be affected by the...     

Historical,temporal, and geographic dynamism of the interaction between Agave and Leptonycteris nectar-feeding bats

Premise

The interaction between ecological and evolutionary processes has been recognized as an important factor shaping the evolutionary history of species. Some authors have proposed different ecological and evolutionary hypotheses concerning the relationships between plants and their pollinators; a special case is the interaction and suspected coevolution among Agave spp. and their main pollinators, the Leptonycteris bats. Agave spp. have, in general, a pollination syndrome compatible with chiropterophily including floral shape and size, nocturnal nectar production, and nectar quality and sugar concentration. Our goal was to analyze the interaction Agave–Leptonycteris and its dynamics during three different climate scenarios.

Methods

We modeled the Agave–Leptonycteris interaction in its spatial and temporal components during the Pleistocene using Ecological Niche Models (ENMs) and three climate scenarios: Current, Last Glacial Maximum (LGM), and Last InterGlacial (LIG). Furthermore, we analyzed the geographic correlation between 96 Agave spp. and two of the Mexican Tequila bats, genus Leptonycteris.

Results

We found that Leptonycteris spp. interact with different Agave spp. over their migratory routes. We propose an interaction refuge in Metztitlán and Tehuacán-Cuicatlán areas, where Agave- Leptonycteris interaction has probably remained active. During the nonmigratory season, both bat species consume nectar of almost the same Agave spp., suggesting the possibility of a diffuse coevolution among Agave and Leptonycteris bats.

Conclusions

We propose that in the areas related to migratory bat movements, each bat species interacts with different Agave spp., whereas in the areas occupied by nonmigrant individuals, both bat species consume nectar of almost the same Agave taxa.

     

Collection of voucher specimens for bat research: conservation,ethical implications,reduction, and alternatives

Voucher specimens have played a fundamental role in biology, but ethical and conservation concerns have been raised over unnecessary collection of organisms. From 1996 to 2017, 222 studies mentioned the collection of 7482 bats of 376 species, mostly from South America and Asia (India, China, and South‐East Asia). Researchers mostly aimed to compile checklists or establish geographic ranges. Strong ethical reasons exist to avoid unnecessary collection, and suitable alternatives should be sought; for example, collecting voucher specimens for retrospective taxonomic confirmation can be replaced with molecular methods. We provide information on alternative methods and when to use them to avoid harming fragile populations of bats.     

Modelling the isometric force response to multiple pulse stimuli in locust skeletal muscle

An improved model of locust skeletal muscle will inform on the general behaviour of invertebrate and mammalian muscle with the eventual aim of improving biomedical models of human muscles, embracing prosthetic construction and muscle therapy. In this article, the isometric response of the locust hind leg extensor muscle to input pulse trains is investigated. Experimental data was collected by stimulating the muscle directly and measuring the force at the tibia. The responses to constant frequency stimulus trains of various frequencies and number of pulses were decomposed into the response to each individual stimulus. Each individual pulse response was then fitted to a model, it being assumed that the response to each pulse could be approximated as an impulse response and was linear, no assumption were made about the model order. When the interpulse frequency (IPF) was low and the number of pulses in the train small, a second-order model provided a good fit to each pulse. For moderate IPF or for long pulse trains a linear third-order model provided a better fit to the response to each pulse. The fit using a second-order model deteriorated with increasing IPF. When the input comprised higher IPFs with a large number of pulses the assumptions that the response was linear could not be confirmed. A generalised model is also presented. This model is second-order, and contains two nonlinear terms. The model is able to capture the force response to a range of inputs. This includes cases where the input comprised of higher frequency pulse trains and the assumption of quasi-linear behaviour could not be confirmed.     

Potential of the predatory mite Amblydromalus zannoui to control pest mites on Jatropha curcas

Amblydromalus zannoui Sourassou, Sarmento and Moraes is a phytoseiid mite of the limonicus group described from central Brazil from leaves of physic nut, Jatropha curcas L. (Malpighiales: Euphorbiaceae), a plant potentially useful as a source of biofuel. This plant is often attacked by the mites Polyphagotarsonemus latus (Banks) (Prostigmata: Tarsonemidae) and Tetranychus bastosi Tuttle, Baker and Sales (Prostigmata: Tetranychidae). The objectives of this work were to evaluate the predation rate of A. zannoui on those phytophagous mites, to assess its life cycle on these prey and on pollen of Ricinus communis L. (Euphorbiaceae), and to determine its attraction to physic nut leaves infested by P. latus or T. bastosi. Amblydromalus zannoui attacked more nymphs and adults than eggs of P. latus, and more eggs and larvae than adults of T. bastosi. The life table parameters suggest that A. zannoui performs better on P. latus (r_m: 0.20, R_o: 18.77; λ: 1.23) and pollen (r_m: 0.18, R_o: 23.32, λ: 1.18). The predator seems to be attracted to plants with P. latus, but attraction was not clear cut for plants with T. bastosi. The results suggested that A. zannoui is a potential control agent to be used against P. latus on physic nut plants, and that R. communis pollen can be used as supplementary food to maintain the predator population in the absence of prey.

     

Scavenging of hydroxyl radical by resveratrol and related natural stilbenes after hydrogen peroxide attack on DNA

Resveratrol (3,5,4′-trihydroxystilbene) is of interest due to its role in prevention and therapy of degenerative diseases as cancer and aging. However, depending on its concentration and cell type studied, resveratrol activity appears conflicting. It exerts antioxidant action, as a scavenger of free radicals and as promoter of antioxidant enzyme activity, but resveratrol acts also as a pro-oxidant. Here we present experimental and theoretical studies for resveratrol and two methoxy-derivatives found in plants, pterostilbene and 3,5,4′-trimethoxystilbene. We show that both methoxy-derivatives induce less DNA damage than resveratrol. The protective effects of the three molecules against oxidative DNA damage induced by hydrogen peroxide treatment were analyzed on mammalian cells in vitro. Our data show for the first time that methoxylated derivatives of resveratrol are very efficient in reducing DNA damage: using the same concentration of the three molecules we obtain a relative reduction of 85.5% (pterostilbene), 43.7% (trimethoxystilbene) and 21.1% (resveratrol). Analysis of the crystal structures of pterostilbene and 3,5,4′-trimethoxystilbene, compared to resveratrol, show fewer intermolecular interactions and a lack of planarity, due to packing forces, which is confirmed by density functional theory (DFT) calculations. We also describe the results of DFT calculations (including water solvent effects) in which the three stilbene species scavenge the hydroxyl radical (associated with the H₂O₂ insult).     

COVID-19, media coverage of bats and related Web searches: a turning point for bat conservation?

1. SARS-CoV-2, the virus that caused the COVID-19 pandemic, is genomically similar to a SARS-like beta-coronavirus found in Asian rhinolophid bats. This evolutionary relationship impressed the global media, which then emphasised bats as key actors in the spillover that resulted in the pandemic. In this study, we highlight changes in the traditional and new media coverage of bats and in Internet search volumes that occurred since the beginning of the COVID-19 pandemic in 2020.
2. We analysed Google and Wikipedia searches for bats and coronaviruses in 21 countries and eight languages, as well as television broadcasts in the USA, some of which have global coverage, between January 2016 and December 2020. In January 2020, the amount of television news about bats boomed, and news associated with the term ‘bat’ shifted to COVID-19-related topics. A nearly identical pattern was observed in Google searches during 2020 at the global scale. The daily time series of television coverage and Internet search volumes on bats and coronavirus in the USA covaried in the first quarter of 2020, in line with the existence of a media bubble. Time-series analysis revealed that both the Google Trends index and visits to Wikipedia pages about bats boomed in early 2020, despite the fact that this time of year is usually characterised by low search volumes.
3. Media coverage emphasised, correctly or not, the role of bats in the COVID-19 pandemic and amplified public interest in bats worldwide. The public image of these mammals, in many cases threatened and important ecosystem service providers, was seriously compromised. We therefore recommend that policymakers and journalists prioritise scientifically accurate communication campaigns about bats, which would help counteract the surge in bat persecution, and leverage interest towards positive human–bat interactions.

     

Effects of anisotropic interactions on the structure of animal groups

This paper proposes an agent-based model which reproduces different structures of animal groups. The shape and structure of the group is the effect of simple interaction rules among individuals: each animal deploys itself depending on the position of a limited number of close group mates. The proposed model is shown to produce clustered formations, as well as lines and V-like formations. The key factors which trigger the onset of different patterns are argued to be the relative strength of attraction and repulsion forces and, most important, the anisotropy in their application.