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<br>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. <br>Code version: 1.0<br>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. <br>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.<br>If any uncertainties or questions arise whilst accessing these files, please contact [e-mail]软骨鱼纲（Chondrichthyes）强直性静止行为的演化及其适应性意义 强直性静止（tonic immobility）是指暂时性自主运动停止的现象，广泛分布于动物界。该行为通常被视作一种“反捕食”防御策略，但支撑这一假说的实证证据主要局限于陆生脊椎动物。在软骨鱼纲（即鲨鱼、鳐鱼与银鲛）中，尽管相关研究证据匮乏，且其生理机制与陆生类群存在本质差异，但强直性静止也被推测为一种反捕食机制。目前学界对软骨鱼纲中强直性静止的流行程度、演化历史及适应性意义仍知之甚少。本研究提供了12种软骨鱼类经背腹倒置诱导产生的强直性静止行为相关数据。随后，我们运用系统发育比较方法，证实该性状为软骨鱼纲的祖征，且在软骨鱼纲的系统发育历程中曾多次独立丢失。与预期相悖的是，我们未发现强直性静止的演化转变与软骨鱼纲主要生态变异轴之间存在显著相关性。本研究结果对现有假说提出了挑战，并表明强直性静止在现生软骨鱼类中可能并不具备适应性意义，其在软骨鱼纲演化历史中得以保留是因为净适合度成本极低。此外，我们提出强直性静止的丢失与浅水底栖生态系统中的缠绕风险存在关联。本研究结果为解析软骨鱼纲乃至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见解，从而为软骨鱼类生物学及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论文《软骨鱼纲强直性静止行为的演化及其适应性意义》研究结果所需的R代码（Code_S1.R）。代码流程始于数据加载与预处理，随后依次计算系统发育信号、祖先状态重建，并检验TLR与生态变量间的相关性。 此外，本仓库还包含拓展数据集文件“Data_S1.csv”。该文件收录了本研究收集的全部原始数据，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]