Animal Spacing Behaviour: From Home Ranges to Territories

Despite the vast literature on animal space use, quantification of its causes has been elusive. Due to the intrinsic integrative nature of animal spacing behaviour, useful theoretical tools, which measure how an animal responds to the presence of a neighbouring individual as well as how it is affected by the distribution of resources, are still lacking. An important factor in shaping the degree with which neighbours share space and resources, is the social interaction between conspecifics. By building analogies with the world of eusocial insects whereby animals interact via stigmergy, i.e. communicating indirectly by modifying the (chemical) environment in which they wander, we aim to quantify how the degree of home range overlap varies as a function of the propensity of an animal to retreat from locations recently visited by other conspecifics.

Animal Search Strategies

To cope with uncertainty animals gather information that help increase the encounter of preys or food items, nest sites or mate partners. Beneficial knowledge may come in different forms from environmental cues and past experience to eavesdropping conspecifics. To best cope with the the spatio-temporal variability of the resources being searched, animals may use movement strategies that optimize information gathering. Besides the relevance of these strategies to an animal survival, understanding how different movement tactics are selected may provide innovative bio-inspired spatial search algorithm. By analysing movement trajectories of animals in the wild or in artificial arenas, we are interested in deciphering and quantify individual search strategies as a function of the information about resource availability and conspecifics’ presence.

Collective Movement

Movement coordination is often observed in moving animal groups. The reasons for its appearance may be different, but the way in which is accomplished is believed to be quite general: directional alignment of an individual to one of more of its neighbours. Recent empirical and theoretical studies on pairwise characteristics of coordinated flights in echolocating bats have revealed that perceptual biases and delayed alignment are interaction mechanisms sufficient to ensure coordination while avoiding collision. Current directions aim to determine the scalability of these interaction mechanisms and the applicability to animal species with passive, e.g. vision, rather than active sensing.

Macromolecule Escape From Partially Permeable Membranes

To infect cells bacteria like Shigella flexneri, and other Gram-negative pathogens, inject certain proteins within the cellular cytoplasm. The release of these proteins is facilitated by needle-like structures, the so-called Injectisomes or Type III secretion systems, which act as escape routes through the bacterium membrane. The statistics of the protein movement, the size of the needles relative to that of the bacterium and the rate of protein capture at the base of these Injectisomes contribute to the secretion time of the proteins. By representing the protein escape problem as a reaction diffusion process with multiple targets and finite reaction rates, we hope to gain a quantitative understanding of the secretion process and its expected dependence on the diffusion of the proteins and their initial localisations, the numbers of Injectisomes and their position on the bacterium membrane.

Spatial Ecology of Infectious Diseases

Although pathogens are passed between individuals in many different ways, the rate of transmission depends crucially on how often a susceptible and an infected individual ‘encounter’ each other. Identifying when and where transmission events occur is critical to devise effective control strategies. In the context of zoonotic diseases, the transmission of the infection between rodents carrying the Hanta virus is believed to occur mainly via direct contacts. In other cases the transmission may be mediated by a vector, e.g. an insect for the Dengue epdemic. Mediated transmission resulting from revisits of locations recently occupied by infected animals is an important transmission pathway with which badgers infect cows with Mycobacterium bovis, favouring the spread of Bovine Tuberculosis. The frequency with which animals visit the same location either simultaneously or at different moments in time-delayed encounter is one of the basic mechanism that determines if an epidemics will eventually spread. Theoretical models of epidemic propagation based on individual encounters are still in their infancy and how spatial spread depends on the social structure of an animal population is very much in need of answers.