Foerster Stênio Í A
Department of Zoology, University of Tartu, Tartu, Estonia.
PeerJ. 2025 Jan 17;13:e18621. doi: 10.7717/peerj.18621. eCollection 2025.
Body size has always been the focus of several ecological studies due to its undeniable influence on other life-history traits. The conventional representation of body size in arthropods typically relies on linear measures, such as total body length, or the length of specific body parts that can be used to represent body size. While these measures offer simplicity over more complicated alternatives (., dry mass), technical problems persist for arthropods with complex body structures, as is the case for scorpions. In these animals, accurate measurements often require extensive handling, including the stretching of body parts. In light of the difficulties associated with directly measuring total length and carapace length in scorpions (two prevalent proxies for body size in the group), this study evaluates the ability of seven simple linear measurements in predicting length measures of boy size in scorpions under a phylogenetic framework. Predictive equations derived from phylogenetic mixed linear models fitted under Bayesian framework were implemented in custom R functions that can be applied for size prediction in a wide range of scorpions. Overall, accurate predictions of total length and carapace length could be achieved using any of the studied traits as single predictors. However, the most accurate predictions for total length were obtained using the length of metasomal segment V, while the best predictions for carapace length were achieved using telson length. The addition of a secondary predictor had low impact on the quality of the size predictions, indicating that increasing model complexity by incorporating additional predictors is not necessary to achieve accurate size estimates. Technical advantages and limitations associated with each linear measurement are discussed. In conclusion, this study broadens the repertoire of methods available for accurately estimating body size in scorpions, particularly in instances where body size information can only be obtained indirectly through allometric relationships.
由于体型对其他生活史特征有着不可否认的影响，因此它一直是多项生态学研究的重点。节肢动物体型的传统表示方法通常依赖于线性测量，例如总体长或可用于表示体型的特定身体部位的长度。虽然这些测量方法比更复杂的方法（如干质量）更简单，但对于具有复杂身体结构的节肢动物（如蝎子）来说，技术问题仍然存在。在这些动物中，准确测量通常需要大量操作，包括拉伸身体部位。鉴于直接测量蝎子的总长度和背甲长度（该类群中两个普遍的体型替代指标）存在困难，本研究在系统发育框架下评估了七种简单线性测量方法预测蝎子体型长度测量值的能力。从贝叶斯框架下拟合的系统发育混合线性模型中导出的预测方程，通过自定义R函数实现，可应用于广泛的蝎子体型预测。总体而言，使用任何一个研究性状作为单一预测因子都可以实现对总长度和背甲长度的准确预测。然而，使用后体节V的长度对总长度的预测最准确，而使用尾节长度对背甲长度的预测最佳。添加第二个预测因子对体型预测质量的影响较小，这表明通过纳入额外的预测因子来增加模型复杂性对于获得准确的体型估计并非必要。讨论了每种线性测量方法的技术优势和局限性。总之，本研究拓宽了可用于准确估计蝎子体型的方法范围，特别是在只能通过异速生长关系间接获得体型信息的情况下。
