Latitudinal variation in the constitutive and inducible defenses of a canopy-forming rocky intertidal seaweed

A long-standing theory in biogeography is that stronger biotic interactions at lower latitudes select for better-defended phenotypes. However, greater environmental variability at temperate latitudes may also shape defensive strategies by increasing temporal or local spatial variation in consumer pressure and thus selecting for greater phenotypic plasticity, or inducible defenses. Distinguishing between inducible and constitutive defense strategies is therefore necessary to test for latitudinal defense gradients, but also for understanding how species interactions and community dynamics vary across ecological and evolutionary scales. 
We investigated latitudinal variation in antiherbivore defenses of a cosmopolitan rocky intertidal seaweed (Fucus vesiculosus) against a similarly common and abundant grazer (periwinkle snails, Littorina littorea). We used a multi-phase common garden experiment with seaweeds from three different regions along the US Atlantic coast and snails from the ..., Organism Collections- We collected F. vesiculosus seaweeds from nine sites spanning >750km of NW Atlantic coastline and three regions in and around the Gulf of Maine (Fig. 1). Seaweed individuals (one 10-20cm thallus and its holdfast) were collected from the mid-intertidal zone, removing each from the substrate at its holdfast with a metal scraper. Individual holdfasts were separated by >0.25m to avoid sampling genetically identical thalli (N= 80-100 individuals site-1). We avoided seaweeds that were reproductive or visibly damaged. Upon collection, we froze subset of seaweeds (n= 10 site-1) at -20°C for later analysis of ‘in situ’ tissue chemistry. L. littorea snails were collected from one southern and one northern field site (N= 400 site-1; shell length= 15-25 mm). All snails and seaweed were maintained under ambient light and seawater conditions in shallow flow-through tanks (water temperature range 19-21°C). Snails were kept in separate tanks and fed ad libitum with non-exper..., , # Data from: Latitudinal variation in the constitutive and inducible defenses of a canopy-forming rocky intertidal seaweed

**Table of Contents**:

**File Name**: 1_induction_phase_data.csv
**Corresponding Experiment Phase**: Induction Phase
**Summary**: Compiled data from experimental snails and seaweeds during the induction phase used in analyses of grazing rates and post-induction seaweed tissue chemistry presented in Figures 2a, 2b, 2d, 2f, Appendix Tables S1 and S3 and Figure S2.

**File Name**: 2_pre_induction_phloro.csv
**Corresponding Experiment Phase**: Collection and Relaxation Phase
**Summary**: Compiled data from seaweeds frozen before and after the relaxation phase presented in Figure 2c and Appendix Table S2a.

**File Name**: 3_pre_induction_cn.csv\
**Corresponding Experiment Phase**: Collection and Relaxation Phase\
**Summary**: Compiled data from seaweeds frozen before and after the relaxation phase presented in Figure 2e and Appendix Table S2b.

**File Name**: 4_inter_r...,

生物地理学中的一项长期理论认为，低纬度地区更强的生物相互作用会筛选出防御更完善的表型。然而，温带纬度地区更高的环境异质性，也可能通过增强取食压力的时间或局域空间变异，进而筛选出更高的表型可塑性（phenotypic plasticity）或诱导型防御（inducible defenses），从而塑造物种的防御策略。因此，区分诱导型防御与组成型防御策略（constitutive defense strategies），不仅是检验纬度梯度防御格局的必要前提，也有助于理解物种相互作用与群落动态在生态与进化尺度上的变化规律。

我们针对广布岩潮间带海藻——墨角藻（Fucus vesiculosus），以及同域常见且种群丰富的植食螺类——滨螺（Littorina littorea），探究了其抗草食动物防御的纬度变异。本研究采用多阶段共同花园实验（common garden experiment），实验材料分别采自美国大西洋沿岸3个不同区域的海藻，以及……

### 生物样本采集
我们从西北大西洋沿岸750余公里的9个采样点、以及缅因湾及其周边3个区域采集了墨角藻（图1）。从潮间带中区采集单个藻体（长度10~20cm的藻枝及其固着器），使用金属刮刀从基质上剥离其固着器以完整获取样本。个体间固着器间距大于0.25m，以避免采集到遗传一致的藻体（每个采样点采样80~100个个体）。我们避开了生殖期或外观可见损伤的海藻。采样完成后，我们将每个采样点的10个海藻样本置于-20℃冷冻保存，用于后续原位组织化学分析（in situ tissue chemistry）。欧洲滨螺（Littorina littorea）分别采自1个南部和1个北部野外样地（每个样地采集400个个体，壳长15~25mm）。所有海藻与滨螺均在环境自然光与自然海水条件下，饲养于浅型流水养殖缸中（水温范围19~21℃）。滨螺单独饲养，以非实验用海藻自由取食。

# 数据集来源：冠层型岩潮间带海藻的组成型与诱导型防御纬度变异

**数据集目录**：

**文件名**：1_induction_phase_data.csv
**对应实验阶段**：诱导阶段
**数据概述**：整合了诱导阶段实验用滨螺与海藻的相关数据，用于分析取食速率以及诱导后海藻组织化学特征，对应图2a、2b、2d、2f，附录表S1、S3以及图S2。

**文件名**：2_pre_induction_phloro.csv
**对应实验阶段**：采样与恢复阶段
**数据概述**：整合了恢复阶段前后冷冻保存的海藻样本数据，对应图2c以及附录表S2a。

**文件名**：3_pre_induction_cn.csv
**对应实验阶段**：采样与恢复阶段
**数据概述**：整合了恢复阶段前后冷冻保存的海藻样本数据，对应图2e以及附录表S2b。

**文件名**：4_inter_r...