Biology subjects

Porfiri, M.

Publications and source records attributed to Porfiri, M..

3 recordsLinked to original sources

bioRxiv2024

Socially driven negative feedback regulates activity and energy use in ant colonies

Despite almost a century of research on energetics in biological systems, we still cannot explain energy regulation in social groups, like ant colonies. How do individuals regulate their collective activity without a centralized control system? What is the role of social interactions in distributing the workload amongst group members? And how does the group save energy by avoiding being constantly active? We offer new insight into these questions by studying an intuitive compartmental model, calibrated with and compared to data on ant colonies. The model describes a previously unexplored balance between positive and negative social feedback driven by individual activity: when activity levels are low, the presence of active individuals stimulates inactive individuals to start working; when activity levels are high, however, active individuals inhibit each other, effectively capping the proportion of active individuals at any one time. Through the analysis of the system stability, we demonstrate that this balance results in energetic spending at the group level growing proportionally slower than the group size. Our finding is reminiscent of Kleibers law of metabolic scaling in unitary organisms and highlights the critical role of social interactions in driving the collective energetic efficiency of group-living organisms.

biophysics↗

bioRxiv2021

Hydrodynamic model of fish orientation in a channel flow

For over a century, scientists have sought to understand how fish orient against an incoming flow, even without visual and flow cues. Here, we elucidate a potential hydrodynamic mechanism of rheotaxis through the study of the bidirectional coupling between fish and the surrounding fluid. By modeling a fish as a vortex dipole in an infinite channel with an imposed background flow, we establish a planar dynamical system for the cross-stream coordinate and orientation. The system dynamics captures the existence of a critical flow speed for fish to successfully orient while performing cross-stream, periodic sweeping movements. Model predictions are examined in the context of experimental observations in the literature on the rheotactic behavior of fish deprived of visual and lateral line cues. The crucial role of bidirectional hydrodynamic interactions unveiled by this model points at an overlooked limitation of existing experimental paradigms to study rheotaxis in the laboratory.

biophysics↗

bioRxiv2020

Is diversity in worker body size important for the performance of bumble bee colonies?

Specialization and plasticity are important for many forms of collective behavior, but the interplay between these factors is little understood. In insect societies, workers are often predisposed to specialize in different tasks, sometimes with morphological or physiological adaptations, facilitating a division of labor. Workers may also plastically switch between tasks or vary their effort. The degree to which predisposed specialization limits plasticity is not clear and has not been systematically tested in ecologically relevant contexts. We addressed this question in 20 freely-foraging bumble bee (Bombus terrestris) colonies by continually manipulating colonies to contain either a typically diverse or reduced ("homogeneous") worker body size distribution, over two trials. Pooling both trials, diverse colonies did better in several indices of colony performance. The importance of body size was further demonstrated by the finding that foragers were larger than nurses even in homogeneous colonies with a very narrow body size range. However, the overall effect of size diversity stemmed mostly from one trial. In the other trial, homogeneous and diverse colonies showed comparable performance. By comparing behavioral profiles based on several thousand observations, we found evidence that workers in homogeneous colonies in this trial rescued colony performance by plastically increasing behavioral specialization and/or individual effort, compared to same-sized individuals in diverse colonies. Our results are consistent with a benefit to colonies of predisposed (size-diverse) specialists under certain conditions, but also suggest that plasticity or effort, can compensate for reduced (size-related) specialization. Thus, we suggest that an intricate interplay between specialization and plasticity is functionally adaptive in bumble bee colonies.

animal behavior and cognition↗