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David Lusseau

Publications and source records attributed to David Lusseau.

15 recordsLinked to original sources

Resilience of the reported global human-nature interaction network to pandemic conditions

Understanding human-nature interactions and the architecture of coupled human-nature systems is crucial for sustainable development. Cultural ecosystem services (CES), defined as intangible benefits derived from nature exposure, contribute to maintaining and improving human well-being. However, we have limited understanding of how well-being benefits emerge from CES co-production. In this study, for the first time, we estimated the global CES network from self-reported interactions between nature features and human activities underpinning CES co-production using social media. First, we used a bottom-up, approach to define the global repertoire of nature features and human activities used during CES co-production using 682,000 posts on Reddit. We then sampled Twitter to estimate the co-occurrence of these features and activities over the past five years, retrieving 41.7 millions tweets. These tweets were used to estimate the CES bipartite network, where each link was weighted by the number of times nature features and human activities co-occurred in tweets. We expected to observe large changes in the CES network topology in relation to the global mobility restrictions during the COVID-19 pandemic. This was not the case and the global CES network was generally resilient. However, a higher order singular value decomposition of the CES tensor revealed an impulse on the link between self care activities and urban greenspace. This could be due to an increased need for self care during the pandemic and urban greenspace enabling CES to be produced locally. Thus, providing resilience for maintaining well-being during the pandemic. Our user based analysis also indicated a shift towards local CES production during the beginning of the pandemic. Thus, supporting that CES was produced locally. These findings suggest an overall need for CES and access to features providing CES in local communities.

cs.SI

Disparities in greenspace access during COVID-19 mobility restrictions

More than half of the human population lives in cities meaning that most people predominantly experience nature in urban greenspace. Nature exposure is an important contributor to social, mental and physical health. As the world faces a pandemic which threatens the physical and mental health of billions of people, it is crucial to understand that all have the possibility to access nature exposure to alleviate some of these challenges. Here, for the first time, we integrate data from Facebook, Twitter, and Google Search users to show that people looked for greenspace during COVID-19 mobility restrictions but may not have always managed to reach it. People spent more time in areas with greenspace when they could and that depended on the level of multiple deprivation in the neighbourhood where the greenspace was embedded. Importantly, while people sought greenspace throughout the first 20 months of the pandemic, this preference intensified through the waves of lockdown. Living in an affluent area conferred a greenspace advantage in London and Paris but we find that in Berlin more deprived neighbourhoods sought greenspace more, including outside their neighbourhood. This highlights the need to understand how greenspace access and deprivation interact to create more sustainable communities.

cs.SI

A Survey on Physarum Polycephalum Intelligent Foraging Behaviour and Bio-Inspired Applications

In recent years, research on Physarum polycephalum has become more popular after Nakagaki et al. (2000) performed their famous experiment showing that Physarum was able to find the shortest route through a maze. Subsequent researches have confirmed the ability of Physarum-inspired algorithms to solve a wide range of NP-hard problems. In contrast to previous reviews that either focus on biological aspects or bio-inspired applications, here we present a comprehensive review that highlights recent Physarum polycephalum biological aspects, mathematical models, and Physarum bio-inspired algorithms and their applications. The novelty of this review stems from our exploration of Physarum intelligent behaviour in competition settings. Further, we have presented our new model to simulate Physarum in competition, where multiple Physarum interact with each other and with their environments. The bio-inspired Physarum in competition algorithms proved to have great potentials for future research.

cs.AI

Getting a head start: the slime mold, Physarum polycephalum, tune foraging decision to motivational asymmetry when faced with competition

Slime mould plasmodia can adjust their behaviour in response to chemical trails left by themselves and other Physarum plasmodia. This simple feedback process increases their foraging efficiency. We still do not know whether other factors influence plasmodium behaviour in realistic competition settings. Here we designed a competition experiment where two plasmodia had to find one food source in a common environment. As previously shown, the time it took plasmodia to find food depended on their hunger motivation. However, the time it took a plasmodium to start looking for food depended on its motivation and the motivation of its competitor. Plasmodia always initiated foraging quicker if they were in the presence of a competitor and the quickest if they were hungry and in the presence of a satiated competitor. The time it took to arrive to the food was not influenced by whether they were alone or with a competitor. Ultimately, this complex competition response benefited the hungry plasmodia as they had a 4:1 chance of finding the food first. The sensory ecology of Physarum polycephalum is more complex than previously thought and yields complex behaviour in a simple organism.

q-bio.PE

A global assessment of tourism and recreation conservation threats to prioritise interventions

We are increasingly using nature for tourism and recreation, an economic sector now generating more than 10% of the global GDP and 10% of global total employment. This growth though has come at a cost and we now have 5930 species for which tourism and recreation are conservation threats. For the first time we use global social media data to estimate where people go to experience nature and determine how this tourism and recreation pressure overlap with the distribution of threatened species. The more people seek interactions with nature in an area, the larger the number of species threatened by those interactions is. Clear crisis areas emerge where many species sensitive to tourism are exposed to high tourism pressures and those are mainly coastal marine regions. Our current tourism management approaches are not achieving biodiversity conservation. The global increase in nature tourism and recreation is set to continue and we need a global consistent response to mitigate its biodiversity impact. Like with other extractive industries, we must prioritise our efforts to diverge tourism away from crisis areas.

q-bio.PE

The sustainome of global goal interactions varies by country income and is disproportionately influenced by inequalities

We interact with each other and our environment in rich and complex ways. These interactions form socioecological systems in which human, economic, or natural resources are used and replenished. In 2015, the United Nations set seventeen sustainable development goals (SDGs) to attempt to change the way we live and create by 2030 a sustainable future balancing equitable prosperity within planetary boundaries. We have tended to tackle SDGs in isolation and now we realise that a key hurdle to SDG implementation are conflicts arising from SDG interactions. We estimate here for the first time the sustainome, a global picture of those interactions, and determine the main hurdles to maximising SDG implementation. We show that the relative contribution of SDGs to global sustainable success differ by country income. SDG conflicts within the sustainome mean that we must find new ways to address the impacts of climate change, approaches to reducing inequalities and responsible consumption. Focussing on poverty alleviation and reducing inequalities will also have compounded positive effects on the sustainome. This network approach to sustainability provides a way to prioritise SDG and contextualise targets.

physics.soc-ph

The small-world effect is a modern phenomenon

The "small-world effect" is the observation that one can find a short chain of acquaintances, often of no more than a handful of individuals, connecting almost any two people on the planet. It is often expressed in the language of networks, where it is equivalent to the statement that most pairs of individuals are connected by a short path through the acquaintance network. Although the small-world effect is well-established empirically for contemporary social networks, we argue here that it is a relatively recent phenomenon, arising only in the last few hundred years: for most of mankind's tenure on Earth the social world was large, with most pairs of individuals connected by relatively long chains of acquaintances, if at all. Our conclusions are based on observations about the spread of diseases, which travel over contact networks between individuals and whose dynamics can give us clues to the structure of those networks even when direct network measurements are not available. As an example we consider the spread of the Black Death in 14th-century Europe, which is known to have traveled across the continent in well-defined waves of infection over the course of several years. Using established epidemiological models, we show that such wave-like behavior can occur only if contacts between individuals living far apart are exponentially rare. We further show that if long-distance contacts are exponentially rare, then the shortest chain of contacts between distant individuals is on average a long one. The observation of the wave-like spread of a disease like the Black Death thus implies a network without the small-world effect.

physics.soc-ph

Quantum-like perception entanglement leads to advantageous collective decisions

Social animals have to make collective decisions on a daily basis. In most instances, these decisions are taken by consensus, when the group does what the majority of individuals want. Individuals have to base these decisions on the information they perceive from their socioecological landscape. The perception mechanisms they use can influence the cost of collective decisions. Here I show that when group-living individuals perceive their environment concurrently for the same decisions, a quantum-like perception entanglement process can confer less costly collective decisions than when individuals collect their information independently. This highlights a mechanism that can help explain what may seem to be irrational group-living behavior and opens avenues to develop empirical tests for quantum decision theory.

q-bio.PE

The influence of repressive legislation on the structure of a social media network

Social media have been widely used to organize citizen movements. In 2012, 75% university and college students in Quebec, Canada, participated in mass protests against an increase in tuition fees, mainly organized using social media. To reduce public disruption, the government introduced special legislation designed to impede protest organization. Here, we show that the legislation changed the behaviour of social media users but not the overall structure of their social network on Twitter. Thus, users were still able to spread information to efficiently organize demonstrations using their social network. This natural experiment shows the power of social media in political mobilization, as well as behavioural flexibility in information flow over a large number of individuals.

physics.soc-ph

Formalising the multidimensional nature of social networks

Individuals interact with conspecifics in a number of behavioural contexts or dimensions. Here, we formalise this by considering a social network between n individuals interacting in b behavioural dimensions as a nxnxb multidimensional object. In addition, we propose that the topology of this object is driven by individual needs to reduce uncertainty about the outcomes of interactions in one or more dimension. The proposal grounds social network dynamics and evolution in individual selection processes and allows us to define the uncertainty of the social network as the joint entropy of its constituent interaction networks. In support of these propositions we use simulations and natural 'knock-outs' in a free-ranging baboon troop to show (i) that such an object can display a small-world state and (ii) that, as predicted, changes in interactions after social perturbations lead to a more certain social network, in which the outcomes of interactions are easier for members to predict. This new formalisation of social networks provides a framework within which to predict network dynamics and evolution under the assumption that it is driven by individuals seeking to reduce the uncertainty of their social environment.

physics.soc-ph

Incorporating uncertainty into the study of animal social networks

Over the past decade network theory has been applied successfully to the study of a variety of complex adaptive systems. However, the application of these techniques to non-human social networks has several shortfalls. Firstly, in most cases the strength of associations between individuals is disregarded. Secondly, present techniques assume that observed interactions are invariant values and not statistical samples taken from a population. These two simplifications have weakened the value of these techniques when applied to the study of animal social systems. Here we introduce a set of behaviorally meaningful weighted network statistics that can be readily applied to matrices of association indices between pairs of individual animals. We also introduce bootstrapping techniques that estimate the effects of sampling uncertainty on the network statistics and structure. Finally, we discuss the use of randomisation tests to detect the departure of observed network statistics from expected values under null hypotheses of random association given the sampling structure of the data. We use two case studies to show that these techniques provide invaluable insight in the dynamics of interactions within social units and in the community structure of societies.

q-bio.PE

The emergence of unshared consensus decisions in bottlenose dolphins

Unshared consensus decision-making processes, in which one or a small number of individuals make the decision for the rest of a group, are rarely documented. However, this mechanism can be beneficial for all group members when one individual has greater knowledge about the benefits of the decision than other group members. Such decisions are reached during certain activity shifts within the population of bottlenose dolphins residing in Doubtful Sound, New Zealand. Behavioral signals are performed by one individual and seem to precipitate shifts in the behavior of the entire group: side flops are performed by males and initiate traveling bouts while upside-down lobtails are performed by females and terminate traveling bouts. However, these signals are not observed at all activity shifts. We find that while side flops were performed by males that have greater knowledge than other male group members, this was not the case for females performing upside-down lobtails. The reason for this could have been that a generally high knowledge about the optimal timing of travel terminations rendered it less important which individual female made the decision.

q-bio.PE

Evidence for social role in a dolphin social network

Social animals have to take into consideration the behaviour of conspecifics when making decisions to go by their daily lives. These decisions affect their fitness and there is therefore an evolutionary pressure to try making the right choices. In many instances individuals will make their own choices and the behaviour of the group will be a democratic integration of all decisions. However, in some instances it can be advantageous to follow the choice of a few individuals in the group if they have more information regarding the situation that has arisen. Here I provide early evidence that decisions about shifts in activity states in a population of bottlenose dolphin follow such a decision making process. This unshared consensus is mediated by a non-vocal signal which can be communicated globally within the dolphin school. These signals are emitted by individuals that tend to have more information about the behaviour of potential competitors because of their position in the social network. I hypothesise that this decision making process emerged from the social structure of the population and the need to maintain mixed-sex schools.

q-bio.PE

Identifying the role that individual animals play in their social network

Techniques recently developed for the analysis of human social networks are applied to the social network of bottlenose dolphins living in Doubtful Sound, New Zealand. We identify communities and subcommunities within the dolphin population and present evidence that sex- and age-related homophily play a role in the formation of clusters of preferred companionship. We also identify brokers who act as links between subcommunities and who appear to be crucial to the social cohesion of the population as a whole. The network is found to be similar to human social networks in some respects but different in some others such as the level of assortative mixing by degree within the population. This difference elucidates some of the means by which the network formed and evolves.

q-bio.PE

The emergent properties of a dolphin social network

Many complex networks, including human societies, the Internet, the World Wide Web and power grids, have surprising properties that allow vertices (individuals, nodes, Web pages, etc.) to be in close contact and information to be transferred quickly between them. Nothing is known of the emerging properties of animal societies, but it would be expected that similar trends would emerge from the topology of animal social networks. Despite its small size (64 individuals), the Doubtful Sound community of bottlenose dolphins has the same characteristics. The connectivity of individuals follows a complex distribution that has a scale-free power-law distribution for large k. In addition, the ability for two individuals to be in contact is unaffected by the random removal of individuals. The removal of individuals with many links to others does affect the length of the information path between two individuals, but, unlike other scale-free networks, it does not fragment the cohesion of the social network. These self-organizing phenomena allow the network to remain united, even in the case of catastrophic death events.

cond-mat.stat-mech