1,786 research outputs found
Evolutionary ecology of obligate fungal and microsporidian invertebrate pathogens
The interactions between hosts and their parasites and pathogens are omnipresent in the natural world. These symbioses are not only key players in ecosystem functioning, but also drive genetic diversity through co-evolutionary adaptations. Within the speciose invertebrates, a plethora of interactions with obligate fungal and microsporidian pathogens exist, however the known interactions is likely only a fraction of the true diversity. Obligate invertebrate fungal and microsporidian pathogen require a host to continue their life cycle, some of which have specialised in certain host species and require host death to transmit to new hosts. Due to their requirement to kill a host to spread to a new one, obligate fungal and microsporidian pathogens regulate invertebrate host populations. Pathogen specialisation to a single or very few hosts has led to some fungi evolving the ability to manipulate their host’s behaviour to maximise transmission. The entomopathogenic fungus, Entomophthora muscae, infects houseflies (Musca domestica) over a week-long proliferation cycle, resulting in flies climbing to elevated positions, gluing their mouthparts to the substrate surface, and raising their wings to allow for a clear exit from fungal conidia through the host abdomen. These sequential behaviours are all timed to occur within a few hours of sunset. The E. muscae mechanisms used in controlling the mind of the fly remain relatively unknown, and whether other fitness costs ensue from an infection are understudied.European Commissio
Smart Gas Sensors: Materials, Technologies, Practical ‎Applications, and Use of Machine Learning – A Review
The electronic nose, popularly known as the E-nose, that combines gas sensor arrays (GSAs) with machine learning has gained a strong foothold in gas sensing technology. The E-nose designed to mimic the human olfactory system, is used for the detection and identification of various volatile compounds. The GSAs develop a unique signal fingerprint for each volatile compound to enable pattern recognition using machine learning algorithms. The inexpensive, portable and non-invasive characteristics of the E-nose system have rendered it indispensable within the gas-sensing arena. As a result, E-noses have been widely employed in several applications in the areas of the food industry, health management, disease diagnosis, water and air quality control, and toxic gas leakage detection. This paper reviews the various sensor fabrication technologies of GSAs and highlights the main operational framework of the E-nose system. The paper details vital signal pre-processing techniques of feature extraction, feature selection, in addition to machine learning algorithms such as SVM, kNN, ANN, and Random Forests for determining the type of gas and estimating its concentration in a competitive environment. The paper further explores the potential applications of E-noses for diagnosing diseases, monitoring air quality, assessing the quality of food samples and estimating concentrations of volatile organic compounds (VOCs) in air and in food samples. The review concludes with some challenges faced by E-nose, alternative ways to tackle them and proposes some recommendations as potential future work for further development and design enhancement of E-noses
Collective Intelligence and Neurodynamics: Functional Homologies
A deep understanding of the dynamics of the human nervous system requires the
simultaneous study of multiple spatiotemporal scales from the level of
neurotransmitters up to the level of human cultures. This is likely impossible
for technical and ethical reasons. Piecemeal analysis provides some
understanding of the dynamics at single levels, but this does not illuminate
the interactions between levels which are, at the very least, of great
importance clinically. It would be useful to have an accessible biological
system which could serve as a proxy for the nervous system and from which
useful insights might be obtained. Functional homologies between the nervous
system and collective intelligence systems, in particular social insect
colonies, are described. It is proposed that social insects colonies could
serve as functional proxies for nervous systems. Thus a multiscale study of
social insect colonies may provide insights into the dynamics of nervous
systems
Analytical validation of innovative magneto-inertial outcomes: a controlled environment study.
peer reviewe
Social plasticity and limited resilience of coral-dwelling gobies (genus Gobiodon) to climate change: outlook for coral-fish mutualisms in a changing world
Climate change is rapidly altering ecosystems on a global scale, and coral reefs are particularly vulnerable to climate-induced disturbances. Coral reefs depend on mutualisms with their foundation species, i.e. corals, and yet most of the literature has focused on their mutualisms with only one type of symbiont (algae). Little is known about how coral-fish mutualisms respond to climatic disturbances, and yet cyclones and heatwaves are increasingly devastating coral reefs. We urgently need to assess how coral-fish mutualisms respond to disturbances as changes in mutualisms have the potential for causing ecosystem-level changes. Yet fish in coral-fish mutualisms have often been overlooked in studies regarding environmental disturbances. There are multiple aspects of the life history, behaviour, and movement of fish that may impact their mutualisms with corals. Here, I investigated (1) whether both symbionts in coral-fish mutualisms respond similarly to climatic disturbances, and (2) what mechanisms from the fish perspective are likely responsible for how coral-fish mutualisms respond to climatic disturbances. I used a model coral-fish mutualism between coral hosts from the genus Acropora and coral-dwelling gobies from the genus Gobiodon in which both organisms provide important benefits for the resilience of each partner. I implemented a comparative approach by investigating multiple goby and coral species encountered in study locations to provide genus-wide understandings of how their coral-goby mutualisms are impacted by climatic disturbances. Particularly important is that gobies can live in social groups and living in groups can improve coral maintenance. Accordingly, first I provided a comprehensive review on how climate change is impacting the sociality of coral reef fish as the sociality of these taxa have only recently been investigated. Studies have shown that climate change affected the habitat and physiology of fishes, and each of these effects impacted their sociality. The review highlighted key changes to the sociality of these fish depending on how corals respond to disturbances, like reduction in coral size, shifts in coral communities, and health of corals. Secondly, I set the scene by monitoring coral-goby mutualisms throughout four extreme disturbances in the northern Great Barrier Reef (GBR): two cyclones and two heatwaves that caused mass bleaching events. In the aftermath and after a few years of recovery, there were more coral species, but corals were almost three times smaller. For gobies though, there were two times fewer coral species, there were fewer gobies, and most corals became absent of gobies when previously most were occupied. Alarmingly, this study highlighted that gobies declined far more than corals and were far slower to recover than their hosts. Finally, I used a combination of observational and manipulative studies to investigate the potential for coral gobies to exhibit plasticity in their host use, sociality, and movement in relation to disturbances. Following the same four extreme disturbances, I found that gobies shifted hosts to the newly abundant coral species. Although exhibiting host plasticity may be an advantage in the short-term, using alternative coral hosts may reduce the fitness of gobies, i.e. their growth rates. I then investigated whether gobies shifted their social tendencies to live in groups or in pairs following these four extreme disturbances in the northern GBR and following a single extreme disturbance in the southern GBR. Gobies no longer lived in groups, rarely in pairs, and primarily lived as solitary individuals after the four disturbances, whereas there was relatively little change in their social tendencies after the single disturbance. This study suggests that if consecutive disturbances become the norm, gobies may continue to decline if they primarily stay solitary as they need to live in pairs to breed. I then completed another study to investigate how predation risk, coral size and health, and number of group members affected the movement of gobies. I translocated gobies in situ into corals with varying sizes, number of individuals, and health. I replicated the study in a relatively undisturbed environment in Papua New Guinea, and in the highly disturbed environment following the four extreme disturbances in northern GBR. Regardless of the disturbance state, gobies preferred to face high costs of predation and did alter their movement based on coral size, health, or number of group members, even when predation risk was higher in disturbed environments. This suggests that gobies do not alter their movement plasticity based on environmental disturbances even though predation risk is heightened. This means that gobies exhibited host and social plasticity, but they did not exhibit movement plasticity to disturbances. I found that each mechanism of plasticity was likely responsible for a reduced recovery potential of gobies compared to their coral hosts. By combining the findings from each chapter of the thesis, I suggest that coral-fish mutualisms are highly vulnerable to climate change as fish experience barriers to recovery via host, social, and movement plasticity. Future conservation strategies should address declines in fish in order to maintain coral-fish mutualisms important for coral health
Soundscape in Urban Forests
This Special Issue of Forests explores the role of soundscapes in urban forested areas. It is comprised of 11 papers involving soundscape studies conducted in urban forests from Asia and Africa. This collection contains six research fields: (1) the ecological patterns and processes of forest soundscapes; (2) the boundary effects and perceptual topology; (3) natural soundscapes and human health; (4) the experience of multi-sensory interactions; (5) environmental behavior and cognitive disposition; and (6) soundscape resource management in forests
Incorporating Neuro-Inspired Adaptability for Continual Learning in Artificial Intelligence
Continual learning aims to empower artificial intelligence (AI) with strong
adaptability to the real world. For this purpose, a desirable solution should
properly balance memory stability with learning plasticity, and acquire
sufficient compatibility to capture the observed distributions. Existing
advances mainly focus on preserving memory stability to overcome catastrophic
forgetting, but remain difficult to flexibly accommodate incremental changes as
biological intelligence (BI) does. By modeling a robust Drosophila learning
system that actively regulates forgetting with multiple learning modules, here
we propose a generic approach that appropriately attenuates old memories in
parameter distributions to improve learning plasticity, and accordingly
coordinates a multi-learner architecture to ensure solution compatibility.
Through extensive theoretical and empirical validation, our approach not only
clearly enhances the performance of continual learning, especially over
synaptic regularization methods in task-incremental settings, but also
potentially advances the understanding of neurological adaptive mechanisms,
serving as a novel paradigm to progress AI and BI together
Effects of Neonicotinoid Exposure on Anti-predator Behaviour and Learned Recognition of Novel Predator Odour of Larvae Lestes spp. (Odonata: Zygoptera)
Neonicotinoids are widely used water-soluble neurotoxic insecticides. The effects of these
insecticides on non-target aquatic organisms have become a major environmental concern since
they affect both pests and non-target insects. Along with lethal effects, these insecticides could
cause visual and chemoreception impairment. This can lead to behavioural alterations in aquatic
organisms by disrupting the sensory systems used for detecting predators, thereby affecting antipredator behaviours. Therefore, in this thesis, I investigated the effect of imidacloprid, a
neonicotinoid insecticide, on the anti-predator response and learned recognition of novel predator
odour in damselfly larvae (Lestes sp). In the first experiment (chapter 2), damselfly larvae were
exposed to water contaminated with a series of concentrations (0.0μg/L, 0.1μg/L, 1.0μg/L, and
10.0μg/L) of imidacloprid and the change in number of feeding bites performed after injecting a
conspecific damage-released alarm cue solution and a predator kairomone solution was observed
and recorded on day 2, 5, and 10. On days 2 and 5, both the control and 0.1μg/L groups showed
appropriate anti-predator behaviour to alarm cues and predator odour, but this was not the case
for damselflies exposed to 1.0μg/L. By day 10, larvae in the 1.0 and 10.0μg/L groups no longer
responded to alarm cues and all exposure groups ceased responding to predator odour. In the
second experiment (chapter 3), I investigated the effect of exposure to a series of concentrations
of imidacloprid on learned recognition of predatory stimuli by damselfly larvae. Damselflies
were conditioned to recognize risk by exposing them to zebrafish odour (a novel odour)
combined with conspecific damage-released alarm cues or control of dechlorinated water. Larvae
in the control group learned to respond to the predator odour based on their prior conditioning
with alarm cues but not water. Learning of predator odour also occurred for larvae in the 0.1μg/L
treatment group but failed for individuals exposed to the higher concentrations of 1.0μg/Land
10.0μg/L. In the third experiment (chapter 4), I exposed damselfly larvae to imidacloprid (at an
initial pulse solution of 3.0μg/L and reaching a final concentration of 0.01μg/L) during the
conditioning period and evaluated the effect on learned recognition of novel predatory stimuli.
Damselflies were conditioned to recognize risk by exposing them to zebrafish odour with true
conditioning (alarm cue + predator odour) with or without imidacloprid and another group was
given sham conditioning (water + predator odour) with or without imidacloprid exposure. Larvae
given true conditioning without imidacloprid exposure correctly learned to recognize theiii
predator odour as a threat, while larvae given sham conditioning, and those exposed to
imidacloprid, failed to learn to respond to the predator odour. Overall, this study highlights that
acute and chronic exposure to imidacloprid at both environmental relevant and higher
concentrations impairs the anti-predator response to conspecific alarm cues and predator odour
by damselfly larvae. Further, this study demonstrates that imidacloprid affects learned
recognition of novel predator odour by damselfly larvae with the interaction between chemical
cues and imidacloprid potentially playing a key role in this impairment
Social and asocial learning in zebrafish are encoded by a shared brain network that is differentially modulated by local activation
Group living animals use social and asocial cues to predict the presence of reward or punishment in the environment through associative learning. The degree to which social and asocial learning share the same mechanisms is still a matter of debate. We have used a classical conditioning paradigm in zebrafish, in which a social (fish image) or an asocial (circle image) conditioned stimulus (CS) have been paired with an unconditioned stimulus (US=food), and we have used the expression of the immediate early gene c-fos to map the neural circuits associated with each learning type. Our results show that the learning performance is similar to social and asocial CSs. However, the brain regions activated in each learning type are distinct and a community analysis of brain network data reveals segregated functional submodules, which seem to be associated with different cognitive functions involved in the learning tasks. These results suggest that, despite localized differences in brain activity between social and asocial learning, they share a common learning module and social learning also recruits a specific social stimulus integration module. Therefore, our results support the occurrence of a common general-purpose learning module, that is differentially modulated by localized activation in social and asocial learning
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