Anomalous diffusion and search behavior in Caenorhabditis elegans
[eng] In this thesis, our focus was on unraveling how Caenorhabditis elegans samples its environment in the absence of gradients and food resources. We analyzed data from a relocation experiment in which individual worms, including wild-type isolates and defective mutants, were displaced from a food...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/215394 |
| Acceso en línea: | https://hdl.handle.net/2445/215394 http://hdl.handle.net/10803/692238 |
| Access Level: | acceso abierto |
| Palabra clave: | Biocenosis Nematodes Biocenoses |
| Sumario: | [eng] In this thesis, our focus was on unraveling how Caenorhabditis elegans samples its environment in the absence of gradients and food resources. We analyzed data from a relocation experiment in which individual worms, including wild-type isolates and defective mutants, were displaced from a food patch to an empty arena in tightly controlled environmental conditions. We characterized the spreading patterns of the worms and analyzed their movement dynamics at various temporal scales, ranging from milliseconds to hours. Our findings revealed an intricate, time-dependent spreading process, likely driven by internal states and memory relaxation due to the absence of clear external stimuli. Notably, C. elegans exhibited superdiffusive spreading behavior, prompting us to investigate the mechanisms behind this phenomenon and its adaptive significance in search contexts. To this end, we devised a classification algorithm that enabled us to characterize C. elegans trajectories into its elementary motor behaviors: sharp turns and crawls. Leveraging these insights, we developed a mechanistic model of movement that reproduces C. elegans search trajectories in great detail, shedding light on the emergence of superdiffusion. Additionally, we evaluated the search performance of various C. elegans-inspired movement models across multiple spatial scales, assuming two distinct search conditions: symmetric (all targets distant) and asymmetric (near and far targets) scenarios. Through this exercise, we quantitatively assessed the contribution of both superdiffusion and turning dynamics to the search performance of C. elegans. Finally, in an effort to reinforce our theoretical results with a real case study, we conducted a series of experiments with C. elegans individuals foraging in patchy landscapes with bacteria. In these experiments, we employed both homogeneous (regular) and heterogeneous (aggregate) landscapes, mirroring the search conditions evaluated in the synthetic simulations. Our findings confirmed that turning dynamics and superdiffusion are key elements of search behavior in C. elegans, fundamentally shaping its search performance in all landscape configurations analyzed. Furthermore, our results suggest that these two mechanisms have the potential to influence the ecological fitness of the species in the natural environment. While our conclusions are primarily based on the specific experimental conditions analyzed, which involve a sharp transition from resource-plentiful to empty arenas, we believe that the findings we present offer valuable insights into both the understanding of C. elegans search behavior and the adaptive value of superdiffusion and turning dynamics in search processes. |
|---|