Data and code for "The evolution and adaptive significance of tonic immobility in Chondrichthyes"

The evolution and adaptive significance of tonic immobility in ChondrichthyesTonic immobility, a temporary cessation of voluntary movements, is a widespread phenomenon within the animal kingdom. While commonly regarded as an ‘anti-predator’ defence strategy, empirical evidence supporting this hypothesis is predominantly limited to terrestrial vertebrates. In Chondrichthyes (i.e., sharks, rays, and chimaeras), tonic immobility has also been proposed as an anti-predator mechanism, despite a dearth of evidence and fundamental physiological distinctions from terrestrial counterparts. The prevalence, evolutionary history, and adaptive significance of tonic immobility in Chondrichthyes remain poorly understood. Here, we present data regarding tonic immobility induced by dorsoventral inversion across 12 chondrichthyan species. Then, using phylogenetic comparative methods, we demonstrate that this trait is plesiomorphic to Chondrichthyes and has been independently lost multiple times throughout chondrichthyan phylogeny. Contrary to expectations, we find no significant correlation between the evolutionary transitions in tonic immobility and major ecological axes of variation in Chondrichthyes. Our findings challenge existing hypotheses and suggest that tonic immobility may lack adaptive significance in extant chondrichthyans, persisting through chondrichthyan phylogeny due to minimal net fitness costs. Additionally, we propose an association between the loss of tonic immobility and entanglement risk in shallow-water benthic ecosystems. Our results provide unprecedented insights into the evolutionary history of this enigmatic behaviour within Chondrichthyes and across the phylogeny of jawed vertebrates, thus shaping future research directions in chondrichthyan biology and evolutionary ecology. Code version: 1.0This repository contains the R code (Code_S1.R) necessary to reproduce the results from the study "The evolution and adaptive significance of tonic immobility in Chondrichthyes". The workflow outlined in the code begins with loading and processing of data, followed by calculation of phylogenetic signal, ancestral state reconstruction, and tests for correlation between TLR and ecological variables. Additionally, this repository contains the extended data file 'Data_S1.csv'. This file contains all novel data collected during the study, as well as all ecological data gathered from the existing literature. Please consult the methodology for additional details regarding the origins of these data.If any uncertainties or questions arise whilst accessing these files, please contact [e-mail]