Estimating allometric energy allocation between somatic and gonadic growth

• Published in: Methods in ecology and evolution Vol. 13; no. 2; pp. 407 - 418
• Main Authors: Shimadzu, Hideyasu, Wang, Hui‐Yu
• Format: Journal Article
• Language: English
• Published: London John Wiley & Sons, Inc 01.02.2022
• Subjects: allometric scaling; Body mass; diphasic (biphasic); Energy; energy‐based growth model; gradient matching; Growth models; Growth patterns; Mathematical models; Nonlinear systems; Numerical methods; Optimization; Parameter estimation; Statistical analysis; Trichiurus japonicus
• ISSN: 2041-210X; 2041-210X
• DOI: 10.1111/2041-210X.13761

Quantifying growth patterns and energy allocation strategies is essential to comprehend the biological characteristics of organisms and their interactions with broader biological communities in which they reside. Mathematical models, such as mono‐ and diphasic allometric energy‐based growth models, play a pivotal role in delineating such body growth patterns. However, modelling approaches often face some major challenges that stem from both model nonlinearity and data limitation in practice. The present study investigates the nature of the challenges and develops a flexible diphasic allometric growth model. The proposed modelling framework offers an effective parameter estimation approach directly built upon statistical smoothing techniques and numerical optimisation methods. The simulation study undertaken demonstrates that the proposed approach can provide accurate parameter estimates. The illustrative example analyses the individual body and gonadic weight of subtropical cutlassfish Trichiurus japonicus from the cooler northern and warmer southern coasts of Taiwan. The results reveal the linear growth of fish in the south compared with those in the north, which distinctive growth pattern results from the lower dependency to body mass in the somatic and gonadic growth. The proposed unified modelling framework offers new advances in growth modelling to shed light upon the intraspecific life‐history strategies, quantifying growth patterns and energy allocation strategies. 摘要 測量體型成長趨勢與能量分配策略可提升對於生物適應環境的特性及生物間交互作用的了解。體型的成長主要以數學模式描述，模式假設單一或雙階段的特定比例的能量分配，組合產生非線性的成長趨勢。然而，非線性的動態模擬或資料的限制會導致成長模式的應用極為困難。 本研究深入探討成長模式在應用上的困難，並改良目前的雙階段能量分配的成長模式，將特定的能量分配調整為可變化的能量分配。我們建立這個成長模式的工具主要包括統計平滑技術及數值優化方法。 我們的成長模式可估計成長與生殖能量的變化來探討個體成長趨勢。例如，我們以此模式分析台灣北部與南部的日本帶魚(Trichiurus japonicus)個體的體重、生殖腺重、年齡，結果顯示日本帶魚在南部呈現接近線性的成長趨勢，而這個獨特的成長趨勢是由於它們的成長與生殖能量和體型大小的關聯性相對於北部族群比較低。 本研究所提出的成長模式架構將可改進成長模式應用的困難，並且能用於探討同物種內不同的成長、生殖生活史與能量分配的變異。