Size of brain, heart, liver, alimentary tract, and kidneys along altitudinal gradients in Asiatic toad

Brain size variation is frequently linked to energetic trade-offs with other metabolically demanding tissues or organs, a concept central to the expensive brain hypothesis (EBH). In this study, we investigate Asiatic toads (Bufo gargarizans) along altitudinal gradients, focusing on the trade-offs in size between the brain and four key visceral organs: the heart, liver, alimentary tract, and kidney. We estimated brain volume by measurement. We measured the dry weight of four organs: the heart, liver, alimentary tract, and kidneys. Additionally, we measured the snout-vent length and body weight of individuals. Our results indicate that both body size and scaled mass index—an indicator of total energy intake—decrease at higher altitudes, suggesting increased energetic constraints in high altitudinal environments. As altitude rises, we observe a reduction in relative brain size, while the relative sizes of visceral organs tend to increase. Through structural equation modeling, we identify a..., A total of 434 individuals from 15 sites of 3 transects were sampled from west of the Sichuan Basin in 2018 and 2019. All toads were sampled in the breeding season and were breeding adults. All transects were controlled within a straight-line distance of 85 km, which reduces confounding ecological background variables.
Snout vent length (SVL) was used for body size and was measured from photos that were taken from a dorsal view with a ruler as a reference. We measured SVL three times using ImageJ version 1.53g, and used the average value. The scaled mass index (SMI) was used to assess body condition and was calculated by an equation which was described in the related article. 
Brains were dissected out; the cranial nerves, pineal organs, meninx, and pituitary glands (but not the pituitary infundibulum) were removed. Photographs of brains were taken from dorsal, side, and ventral views with a ruler as a reference. The coronal plane and sagittal plane were placed parallel to the camera se..., , # Size of brain, heart, liver, alimentary tract, and kidneys along altitudinal gradients in Asiatic toad

We have submitted our raw data (totalmassdata.csv), R script (totalmassdata.R). 

**Data File: totalmassdata.csv**

ID: Identification of each specimen used in this project

transect: Sampling altitudinal gradient along the river valley, which consists of 4 to 6 sampling populations

site: Sampling population, which consists of individuals captured near the same breeding pond

sex: Determining the sex of individuals through nuptial pads, in which m represents male and f represents female

ALT: Sampling altitude of individuals (km)

ELE: Altitudinal group, which is determined by unpublished principle analysis results with bioclimate data of sampling location. L represents the low altitudinal group, M is the middle altitudinal group, and H is the high altitudinal group

bodymass: Individual’s body weight that was measured by an electronic balance accurate to 0.1 g

heart: Dry weight o...

脑容量变异通常与其他高代谢需求组织或器官的能量权衡密切相关，这一概念是昂贵脑假说（Expensive Brain Hypothesis, EBH）的核心内容。本研究以中华蟾蜍（Bufo gargarizans）为研究对象，沿海拔梯度展开调查，重点探讨脑与心脏、肝脏、消化道和肾脏这四种关键内脏器官之间的大小权衡关系。我们通过测量法估算脑体积，并测定了上述四种器官的干重。此外，我们还测量了个体的吻肛长与体重。

研究结果显示，随着海拔升高，个体体型与代表总能量摄入指标的标准化体重指数（Scaled Mass Index, SMI）均呈下降趋势，表明高海拔环境下的能量限制作用更强。伴随海拔上升，相对脑容量显著降低，而内脏器官的相对体积则呈现上升趋势。通过结构方程模型，我们发现……本研究共于2018年与2019年在四川盆地西部3条样带的15个采样点采集了434只个体，所有样本均采集于繁殖季，均为繁殖成体。所有样带的直线距离均控制在85 km以内，以减少混杂的生态背景变量带来的干扰。

本研究以吻肛长（Snout-Vent Length, SVL）作为体型指标，通过以标尺为参照的背视图照片进行测量，使用ImageJ 1.53g版本进行三次测量后取平均值。标准化体重指数（SMI）用于评估个体身体状况，其计算公式参照已发表的相关研究文献。

剥离脑组织后，去除其中的脑神经、松果体、脑膜及垂体（垂体漏斗部除外）。我们以标尺为参照，从背侧、侧面与腹侧三个视角拍摄脑组织照片。冠状面与矢状面均与相机传感器保持平行……

# 中华蟾蜍沿海拔梯度的脑、心脏、肝脏、消化道及肾脏尺寸变化
本研究已提交原始数据文件totalmassdata.csv与R脚本文件totalmassdata.R。

**数据文件：totalmassdata.csv**
各字段说明如下：
ID：本研究中每个标本的唯一标识
transect：沿河谷布设的海拔梯度样带，每条样带包含4至6个采样种群
site：采样种群，指在同一繁殖池塘附近捕获的个体集合
sex：通过婚垫鉴定个体性别，其中m代表雄性，f代表雌性
ALT：个体的采样海拔（单位：km）
ELE：海拔分组，基于采样点生物气候数据的未公开主成分分析结果划分，L代表低海拔组，M代表中海拔组，H代表高海拔组
bodymass：使用精度达0.1 g的电子天平测定的个体体重
heart：心脏干重……