Body size mediates trophic interaction strength of novel fish assemblages under climate change

Ecological similarity plays an important role in biotic interactions. Increased body size similarity of competing species, for example, increases the strength of their biotic interactions. Body sizes of many exothermic species are forecast to be altered under global warming, mediating shifts in existing trophic interactions amongst species, in particular for species with different thermal niches. Temperate rocky reefs along the southeast coast of Australia are climate hotspots and now house a mixture of temperate native fish species and poleward range-extending tropical fishes (vagrants), creating novel species assemblages. Here, we studied the relationship between body size similarity and trophic overlap between individual temperate native and tropical vagrant fishes. Dietary niche overlap between vagrant and native fish species increased as their body sizes converged, based on both stomach content composition (short-term diet), stable isotopes analyses (integrated long-term diet) and ..., We used a small hand net and a mixture of ethanol and clove oil to capture juveniles of six native temperate species (Ambassis jacksoniensis, Atypichthys strigatus, Microcanthus strigatus, Parma microlepis, Pempheris affinis, Trachinops taeniatus) and of three tropical vagrant species (Abudefduf sexfasciatus, A. vaigiensis, Pomacentrus wardi) along the southeast coast of Australia between latitudes 30.8º and 36.8ºS.
For stomach content analysis, the entire gut was removed from each frozen fish, and the abundance of each prey item (excluding vegetation) inside the stomach was visually counted, their maximum lengths measured, and identified at family level using a stereo microscope. Autotroph prey items including algae and seagrass were grouped together, as the partly digested vegetation could not be identified, and their contribution to the diet was estimated as a count. Then, we calculated Bray-Curtis similarity index using on stomach contents.
For stable isotope analysis, white muscle ..., , # Body size mediates trophic interaction strength of novel fish assemblages under climate change

[https://doi.org/10.5061/dryad.w9ghx3fx8](https://doi.org/10.5061/dryad.w9ghx3fx8)

Dataset provides 1) Bray-Curtis similarity index based on stomach contest, 2) Euclidean similarity index based using stable isotope signatures, and 3) proportional similarity in median prey size per fish stomach.

Please refer our paper for experimental procedures, data collection, analysis and results.

## Description of the data and file structure

Three datasets have seven columns, and first five columns contain variables that are same across three datasets (1-5) and remaining sixth (6) and seventh (7) columns contains distance indexes. Brief description of column names are as indicated below;

1\) ID1: Identifier of species 1 in comparison

2\) ID2: Identifier of species 2 in comparison

3\) Species_pair: Abbreviated names of two species in comparison

4\) Site: Abbreviated name of sampling site where sp...

生态相似性在生物互作中发挥着关键作用。例如，竞争物种间的体型相似性越高，二者的生物互作强度便越强。全球变暖背景下，多数外温物种（exothermic species）的体型预计将发生改变，这将介导物种间现存营养互作的动态转变，尤其针对具有不同热生态位（thermal niche）的类群。澳大利亚东南沿海的温带岩礁属于气候热点区域，当前栖息着温带本土鱼类与向极域扩散的热带迷逸鱼类，形成了全新的物种集合群落。本研究聚焦温带本土鱼类与热带迷逸鱼类个体间的体型相似性与营养生态位重叠之间的关联。基于胃含物组成（短期摄食记录）与稳定同位素分析（stable isotope analysis，长期整合的摄食信息），迷逸鱼类与本土鱼类的营养生态位重叠度随二者体型趋同而升高，且……

我们于澳大利亚东南沿海30.8°S至36.8°S的海域内，使用小型手操网与乙醇-丁香油混合麻醉剂，采集了6种温带本土鱼类（杰克逊玻璃鱼Ambassis jacksoniensis、条纹澳小棘鱼Atypichthys strigatus、细鳞雀鲷Microcanthus strigatus、小鳞雀鲷Parma microlepis、近邻金眼鲷Pempheris affinis、带纹拟雀鲷Trachinops taeniatus）与3种热带迷逸鱼类（六带豆娘鱼Abudefduf sexfasciatus、豆娘鱼A. vaigiensis、瓦氏雀鲷Pomacentrus wardi）的幼体样本。

针对胃含物分析：我们将每尾冷冻样本的完整肠道取出，目视计数胃内各猎物类群（排除植物类）的丰度，测量其最大体长，并借助体视显微镜将猎物鉴定至科水平。由于部分消化的植物组织无法精准鉴定，我们将藻类、海草等自养型猎物归为一类，并以计数方式估算其在日粮中的占比。随后，我们基于胃含物数据计算了Bray-Curtis相似性指数（Bray-Curtis similarity index）。

针对稳定同位素分析，取白色肌肉组织……

# 气候变化下体型介导新型鱼类集合群落的营养互作强度
[https://doi.org/10.5061/dryad.w9ghx3fx8](https://doi.org/10.5061/dryad.w9ghx3fx8)

本数据集包含三类数据：1）基于胃含物的Bray-Curtis相似性指数；2）基于稳定同位素特征的欧氏相似性指数（Euclidean similarity index）；3）单尾鱼类胃内含物中位猎物体型的比例相似性。

实验流程、数据采集、分析方法与研究结果详见本团队发表的论文。

## 数据与文件结构说明
本数据集包含三份数据表，每份均含7列。其中前5列为三份数据表共享的通用变量，第6、7列为距离指数类变量。各列名称的简要说明如下：
1) ID1：比对物种1的唯一标识符
2) ID2：比对物种2的唯一标识符
3) Species_pair：比对的两个物种的缩写名称
4) Site：采样位点的缩写名称
5) ……