Search

Mammalian herbivores browse palatable plants of ecological and economical value. Undesirable neighbours can reduce browsing to these plants by providing 'associational refuge', but they can also compete for resources. Here we recreated the informative odour emitted by undesirable plants. We then tested whether this odour could act as virtual neighbours, providing browsing refuge to palatable eucalyptus tree seedlings. We found that protection using this method was equivalent to protection provided by real plants. Palatable seedlings were 17-20 times more likely to be eaten by herbivores without virtual, or real, neighbours. Because many herbivores use plant odour to forage, virtual neighbours could provide a useful practical management approach to help protect valued plants., (© 2024. The Author(s).)

When foraging, making appropriate food choices is crucial to an animal's fitness. Classic foraging ecology theories assume animals choose food of greatest benefit based on their absolute value across multiple dimensions. Consequently, poorer options are considered irrelevant alternatives that should not influence decision-making among better options. But heuristic studies demonstrate that irrelevant alternatives (termed decoys) can influence the decisions of some animals, indicating they use a relative rather than absolute evaluation system. Our aim was to test whether a decoy influenced the decision-making process-that is, information-gathering and food choice-of a free-ranging mammalian herbivore. We tested swamp wallabies, Wallabia bicolor, comparing their behavior toward, and choice of, two available food options over time in the absence or presence of the decoy. We used a phantom decoy-unavailable option-and ran two trials in different locations and seasons. Binary preferences (decoy absent) for the two available food options differed between trials. Irrespective of this difference, across both trials the presence of the decoy resulted in animals more likely to overtly investigate available food options. But, the decoy only shifted food choice, weakly, in one trial. Our results indicate that the decoy influenced the information-gathering behavior during decision-making, providing the first evidence that decoys can affect decision-making process of free-ranging mammalian herbivores in an ecologically realistic context. It is premature to say these findings confirm the use of relative evaluation systems. Whether the foraging outcome is more strongly affected by other decoys, food dimensions, or ecological contexts, is yet to be determined., Competing Interests: We confirm that this manuscript has not been published elsewhere and is not under consideration by another journal. All authors have approved the manuscript and agree to its submission. We declare no conflicts of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology.)

All organisms emit odour, providing 'open-access' olfactory information for any receiver with the right sensory apparatus. Characterizing open-access information emitted by groups of organisms, such as plant species, provides the means to answer significant questions about ecological interactions and their evolution. We present a new conceptual framework defining information reliability and a practical method to characterize and recover information from amongst olfactory noise. We quantified odour emissions from two tree species, one focal group and one outgroup, to demonstrate our approach using two new R statistical functions. We explore the consequences of relaxing or tightening criteria defining information and, from thousands of odour combinations, we identify and quantify those few likely to be informative. Our method uses core general principles characterizing information while incorporating knowledge of how receivers detect and discriminate odours. We can now map information in consistency-precision reliability space, explore the concept of information, and test information-noise boundaries, and between cues and signals., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)

This work aims to characterize, in mineral and chemical terms, the ore tailings related to the Mariana disaster (MG, Brazil), occurred on 5 November 2015, and assess its correlation with sediments found in the continental shelf adjacent to the Doce River mouth (ES, Brazil). This study uses samples of tailings and seabed sediments collected at the mouth of the Doce River from 2012 to 2019. Elemental compositions of all samples were determined by X-ray fluorescence measurements; however, Synchrotron Resonant X-Ray Diffraction proved to be a remarkable technique to characterize the crystallographic phases of iron present in sediments. Studies and analyzes of the sediment samples showed that the tailings have a notable feature of the iron-crystallographic phases, mainly observed in the period after the Fundão dam failure, as compared with sediments collected in the period before. This set of iron-containing mineral phases, here called the Iron Mineralogical Set (IMS), consists of the main phases of hematite and magnetite and the minority phases of goethite and greenalite and it is used as a marker of tailings. Mass ac magnetic susceptibility measures supported the concept of the IMS as a marker. It is suggested a relationship between the content of the IMS in the sediment samples as a function of the measures of mass magnetic susceptibility. The IMS had shown the influence of tailings on the sea bed sediment indicating that there is no possibility, at the current stage, of predicting how many years this material will still be at the seabed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Foraging by mammalian herbivores has profound impacts on natural and modified landscapes, yet we know little about how they find food, limiting our ability to predict and manage their influence. Mathematical models show that foragers exploiting odour cues outperform a random walk strategy. However, discovering how free-ranging foragers exploit odours in real, complex landscapes has proven elusive because of technological constraints. We took a novel approach, using a sophisticated purpose-built thermal camera system to record fine-scale foraging by a generalist mammalian herbivore, the swamp wallaby ( Wallabia bicolor ). We tested the hypothesis that odour cues shape forager movement and behaviour in vegetation patches. To do this, we compared wallaby foraging in two odour landscapes: Control (natural vegetation with food and non-food plants interspersed) and +Apple (the same natural vegetation plus a single, highly palatable food source with novel odour (apple)). The +Apple treatment led to strongly directed foraging by wallabies: earlier visits to vegetation patches, straighter movement paths, more hopping and fewer stops than in the Control treatment. Our results provide clear empirical evidence that odour cues are harnessed for efficient, directed search even at this fine scale. We conclude that random walk models miss a key feature shaping foraging within patches.

The crystal and local atomic structure of monoclinic ReO2 (alpha-ReO2) under hydrostatic pressure up to 1.2 GPa was investigated for the first time using both X-ray absorption spectroscopy and high-resolution synchrotron X-ray powder diffraction and a home-built B4C anvil pressure cell developed for this purpose. Extended X-ray absorption fine-structure (EXAFS) data analysis at pressures from ambient up to 1.2 GPa indicates that there are two distinct Re-Re distances and a distorted ReO6 octahedron in the alpha-ReO2 structure. X-ray diffraction analysis at ambient pressure revealed an unambiguous solution for the crystal structure of the alpha-phase, demonstrating a modulation of the Re-Re distances. The relatively small portion of the diffraction pattern accessed in the pressure-dependent measurements does not allow for a detailed study of the crystal structure of alpha-ReO2 under pressure. Nonetheless, a shift and reduction in the (011) Bragg peak intensity between 0.4 and 1.2 GPa is observed, with correlation to a decrease in Re-Re distance modulation, as confirmed by EXAFS analysis in the same pressure range. This behavior reveals that alpha-ReO2 is a possible inner pressure gauge for future experiments up to 1.2 GPa.