Animal Interactions and the Emergence of Territoriality

Inferring the role of interactions in territorial animals relies upon accurate recordings of the behaviour of neighbouring individuals. Such accurate recordings are rarely available from field studies. As a result, quantification of the interaction mechanisms has often relied upon theoretical approaches, which hitherto have been limited to comparisons of macroscopic population-level predictions from un-tested interaction models. Here we present a quantitative framework that possesses a microscopic testable hypothesis on the mechanism of conspecific avoidance mediated by olfactory signals in the form of scent marks. We find that the key parameters controlling territoriality are two: the average territory size, i.e. the inverse of the population density, and the time span during which animal scent marks remain active. Since permanent monitoring of a territorial border is not possible, scent marks need to function in the temporary absence of the resident. As chemical signals carried by the scent only last a finite amount of time, each animal needs to revisit territorial boundaries frequently and refresh its own scent marks in order to deter possible intruders. The size of the territory an animal can maintain is thus proportional to the time necessary for an animal to move between its own territorial boundaries. By using an agent-based model to take into account the possible spatio-temporal movement trajectories of individual animals, we show that the emerging territories are the result of a form of collective animal movement where, different to shoaling, flocking or herding, interactions are highly heterogeneous in space and time. The applicability of our hypothesis has been tested with a prototypical territorial animal, the red fox (Vulpes vulpes)

Knowing your neighbours: how memory-mediated conspecific avoidance influences home ranges

3openInternationalInternational coauthor/editorIn Focus: Ellison, N., Hatchwell, B. J., Biddiscombe, S. J., Napper, C. J., & Potts, J. R. (2020). Mechanistic home range analysis reveals drivers of space use patterns for a non-territorial passerine. Journal of Animal Ecology. https://doi.org/10.1111/1365- 2656.13292. Most animals for which space use has been studied restrict their movements into a constrained spatial area: their home range. The ubiquity of this space-use pattern suggests that home ranges are adaptive in a wide range of ecological contexts, and that they likely arise from general biological mechanisms. In this issue, Ellison et al. use a mechanistic home range analysis (MHRA) to uncover the drivers underlying home range patterns in a passerine that is non-territorial. They show that a model integrating both resource preferences (specifically, an attraction to woodland centre), and memory-mediated conspecific avoidance can capture the space-use patterns observed in a wild population of long-tailed tits Aegithalos caudatus. In doing so, their analysis extends the applicability of MHRA to capturing and predicting home range patterns beyond the previously studied cases where spatially exclusive home ranges emerge from scent mark-mediated avoidance responses to neighbouring groups.openRanc, N.; Cagnacci, F.; Moorcroft, P.R.Ranc, N.; Cagnacci, F.; Moorcroft, P.R

Rumsliga mönster i djurterritorialitet : konkurrerande beteende hos en snäckskalslevande Ciklid

Sociality among animals is a common phenomenon which has both costs and benefits. More and more studies are published that uses shell dwelling cichlids as a proxy for other taxa because of their convenience when studying, unique evolution and large variety in species. In this study, videos of the species Neolamprologus Multifasciatus from Lake Tanganyika has been used to investigates two different questions: 1) If there are any differences between territories of the species on the edge of the larger groups compared to territories in the centre. 2) If N. multifasciatus uses sand digging behaviour to gain a competitive advantage against neighbouring territories by depositing sand in the direction of them. This thesis found that there is no significant difference between edge groups and centre groups in the parameters we analysed (aggressive behaviour from the dominant male, time of heterospecific intrusion, digging behaviour of the dominant male, number of group hiding events and time dominant male spends in shell). The thesis also found that N. multifasciatus deposits sand in the direction of neighbours more often than would be predicted by chance. We further discuss both our small sample size as well as what our findings means in a broader behavioural context in animals, especially terrestrial animal

Territorial Developments Based on Graffiti: a Statistical Mechanics Approach

We study the well-known sociological phenomenon of gang aggregation and territory formation through an interacting agent system defined on a lattice. We introduce a two-gang Hamiltonian model where agents have red or blue affiliation but are otherwise indistinguishable. In this model, all interactions are indirect and occur only via graffiti markings, on-site as well as on nearest neighbor locations. We also allow for gang proliferation and graffiti suppression. Within the context of this model, we show that gang clustering and territory formation may arise under specific parameter choices and that a phase transition may occur between well-mixed, possibly dilute configurations and well separated, clustered ones. Using methods from statistical mechanics, we study the phase transition between these two qualitatively different scenarios. In the mean-field rendition of this model, we identify parameter regimes where the transition is first or second order. In all cases, we have found that the transitions are a consequence solely of the gang to graffiti couplings, implying that direct gang to gang interactions are not strictly necessary for gang territory formation; in particular, graffiti may be the sole driving force behind gang clustering. We further discuss possible sociological -- as well as ecological -- ramifications of our results

The Influence of Sex and Season on Conspecific Spatial Overlap in a Large, Actively-Foraging Colubrid Snake

Understanding the factors influencing the degree of spatial overlap among conspecifics is important for understanding multiple ecological processes. Compared to terrestrial carnivores, relatively little is known about the factors influencing conspecific spatial overlap in snakes, although across snake taxa there appears to be substantial variation in conspecific spatial overlap. In this study, we described conspecific spatial overlap of eastern indigo snakes (Drymarchon couperi) in peninsular Florida and examined how conspecific spatial overlap varied by sex and season (breeding season vs. non-breeding season). We calculated multiple indices of spatial overlap using 6- and 3-month utilization distributions (UD) of dyads of simultaneously adjacent telemetered snakes. We also measured conspecific UD density values at each telemetry fix and modeled the distribution of those values as a function of overlap type, sex, and season using generalized Pareto distributions. Home range overlap between males and females was significantly greater than overlap between individuals of the same sex and male home ranges often completely contained female home ranges. Male home ranges overlapped little during both seasons, whereas females had higher levels of overlap during the non-breeding season. The spatial patterns observed in our study are consistent with those seen in many mammalian carnivores, in which low male-male overlap and high inter-sexual overlap provides males with greater access to females. We encourage additional research on the influence of prey availability on conspecific spatial overlap in snakes as well as the behavioral mechanisms responsible for maintaining the low levels of overlap we observed

Bacterial secretion and the role of diffusive and subdiffusive first passage processes

Open Access ArticleBy funneling protein effectors through needle complexes located on the cellular membrane, bacteria are able to infect host cells during type III secretion events. The spatio-temporal mechanisms through which these events occur are however not fully understood, due in part to the inherent challenges in tracking single molecules moving within an intracellular medium. As a result, theoretical predictions of secretion times are still lacking. Here we provide a model that quantifies, depending on the transport characteristics within bacterial cytoplasm, the amount of time for a protein effector to reach either of the available needle complexes. Using parameters from Shigella flexneri we are able to test the role that translocators might have to activate the needle complexes and offer semi-quantitative explanations of recent experimental observations.Engineering and Physical Sciences Research Council (EPSRC)Medical Research Council (MRC

Species Composition and Spatial Ecology of Amazonian Understory Mixed-Species Flocks in a Fragmented Landscape

With the ongoing advance of the agricultural frontier in the Amazon basin, it is inevitable that heterogeneous landscapes will play a key role in conservation. These landscapes are mostly composed of patchworks of small forest fragments, secondary forests and roads. Conservation, however must take species interactions into consideration as they play a pivotal part the maintenance of several biological processes in the tropics. One of the most conspicuous interspecific interactions are seen in mixed-species flocks of birds, which in the Amazon, represent one of the best organized systems of bird aggregations. In this research, I assess how flock spatial behavior and species compositions are affected by changes in habitat structure. I followed 29 mixed-species flocks in different landscapes types such as secondary forests, forest fragments of 10 and 100 ha, and mixes of primary and secondary forest patches. As flocks foraged through their territories, I recorded their species composition every 30 minutes and georeferenced their movements every 30 seconds. Flocks spatial behavior was severely affected by anthropogenic features such as forest edges and secondary forests as flocks respond strongly to vegetation height. Using step-selection models, it was possible to reproduce flock movements and show that they prefer taller vegetation and lower areas of topography such as stream valleys. Due to this behavior, flocks avoided areas where canopy height was below 15 meters, and extensive areas of secondary below this height hold unstable flocks that do not persist for long periods. The ones that persisted showed home ranges that were much larger than what was observed in primary forest. Time spent in secondary forest was dependent on vegetation height, but not area, which seems to be shaped by intraspecific interactions. Flock social structure is also severely affected by habitat structure. Flock species richness did not show a predictable pattern, but participation was negatively affected. In fact, our data indicates that flock social structure may take longer to recover than spatial behavior. Assessing a 30-year mist-net capture dataset, we were able to determine that indeed, decreased species participation seems to be a more important driver in flock dissolution than local extinction

Reconstructing the intrinsic statistical properties of intermittent locomotion through corrections for boundary effects

Locomotion characteristics are often recorded within bounded spaces, a constraint which introduces geometry-specific biases and potentially complicates the inference of behavioural features from empirical observations. We describe how statistical properties of an uncorrelated random walk, namely the steady-state stopping location probability density and the empirical step probability density, are affected by enclosure in a bounded space. The random walk here is considered as a null model for an organism moving intermittently in such a space, that is, the points represent stopping locations and the step is the displacement between them. Closed-form expressions are derived for motion in one dimension and simple two-dimensional geometries, in addition to an implicit expression for arbitrary (convex) geometries. For the particular choice of no-go boundary conditions, we demonstrate that the empirical step distribution is related to the intrinsic step distribution, i.e. the one we would observe in unbounded space, via a multiplicative transformation dependent solely on the boundary geometry. This conclusion allows in practice for the compensation of boundary effects and the reconstruction of the intrinsic step distribution from empirical observations

Weakly nonlinear analysis of a two-species non-local advection–diffusion system

Nonlocal interactions are ubiquitous in nature and play a central role in many biological systems. In this paper, we perform a bifurcation analysis of a widely-applicable advection–diffusion model with nonlocal advection terms describing the species movements generated by inter-species interactions. We use linear analysis to assess the stability of the constant steady state, then weakly nonlinear analysis to recover the shape and stability of non-homogeneous solutions. Since the system arises from a conservation law, the resulting amplitude equations consist of a Ginzburg–Landau equation coupled with an equation for the zero mode. In particular, this means that supercritical branches from the Ginzburg–Landau equation need not be stable. Indeed, we find that, depending on the parameters, bifurcations can be subcritical (always unstable), stable supercritical, or unstable supercritical. We show numerically that, when small amplitude patterns are unstable, the system exhibits large amplitude patterns and hysteresis, even in supercritical regimes. Finally, we construct bifurcation diagrams by combining our analysis with a previous study of the minimizers of the associated energy functional. Through this approach we reveal parameter regions in which stable small amplitude patterns coexist with strongly modulated solutions