Data and code for "<b>The evolution and adaptive significance of tonic immobility in Chondrichthyes</b>"

The evolution and adaptive significance of tonic immobility in Chondrichthyes Tonic 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: 1.0 This 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]软骨鱼纲（Chondrichthyes）中强直静止（tonic immobility）的演化及其适应性意义 强直静止（tonic immobility）指暂时性自主运动停止，是动物界广泛分布的现象。尽管该行为常被视作“反捕食”防御策略，但支撑这一假说的实证证据目前主要局限于陆生脊椎动物。在软骨鱼纲（Chondrichthyes，即鲨类、鳐类与银鲛类）中，强直静止也被推测为一种反捕食机制，然而相关研究证据匮乏，且该行为与陆生同类存在根本性生理差异。目前学界对软骨鱼纲中强直静止的流行程度、演化历史及其适应性意义仍知之甚少。 本研究收集了12种软骨鱼类经背腹翻转诱导产生的强直静止相关数据。随后，本研究借助系统发育比较方法证实，该性状为软骨鱼纲的祖征，且在软骨鱼的系统发育历程中已独立丢失多次。与预期相悖的是，本研究未发现强直静止的演化转变与软骨鱼纲主要生态变异维度间存在显著关联。本研究结果对现有假说提出了挑战，表明现存软骨鱼类的强直静止可能并不具备适应性意义，其在软骨鱼系统发育中得以保留是因为净适合度成本极低。此外，本研究还提出，强直静止的丢失与浅水底栖生态系统中的缠绕风险存在关联。本研究结果为揭示软骨鱼纲乃至整个有颌脊椎动物中这一神秘行为的演化历史提供了前所未有的视角，为软骨鱼类生物学与进化生态学领域的未来研究指明了方向。 代码版本：1.0 本数据集仓库包含复现本研究《软骨鱼纲中强直静止的演化及其适应性意义》结果所需的R代码（Code_S1.R）。代码中的分析流程依次为：数据加载与预处理、系统发育信号计算、祖先状态重建，以及TLR与生态变量间的相关性检验。 此外，本仓库还包含扩展数据文件Data_S1.csv。该文件涵盖本研究收集的全部全新数据，以及从已有文献中整合的所有生态数据。如需了解这些数据来源的更多细节，请查阅研究方法部分。 若在访问上述文件时存在任何疑问或问题，请联系[e-mail]