Horseshoe crab body size cline

Aim
Adult body size often exhibits patterns across large-scale environmental gradients, creating ecogeographic clines. However, the form of body size clines varies across taxonomic groups, with linear and non-linear patterns in body size observed in nature. Non-linear body size clines have received less study, and questions remain about how environmental gradients interact to produce non-linear clines. We examined the body size of the American horseshoe crab (Limulus polyphemus), a widely distributed marine arthropod, and evaluated the hypothesis that temperature and active season length can interact multiplicatively to result in a dome-shaped distribution.
Location
Fourteen states in the United States of America and three Mexican states, representing the entire geographic range of the species.
Methods
We compiled environmental data and body size measurements from more than 49,000 individual horseshoe crabs. For each location, we extracted from the literature or calculated from raw data..., Data Collection
Body Size Data
We searched journal articles, books, and federal and state agency reports for published information on the body size of mature adult horseshoe crabs in North America. We also located an unpublished manuscript that added information from Delaware Bay and a Smithsonian Institution website provided sizes for animals from the Indian River Lagoon in Florida, USA. We supplemented these with original field data collected from Stony Brook, New York, USA (2007); Skidaway (2007) and Sapelo (2009) Islands, Georgia, USA; Seahorse Key, Florida, USA (1995–1997, 2007–2009); and the citizen science program Florida Horseshoe Crab Watch (2015–2022; Heres et al., 2021). 
In total, we compiled measurements from 49,877 individuals from 77 different locations in North America (14 USA states and 3 Mexican states), representing the entire geographic range of the species. For each location, we extracted from the literature or calculated from raw data the mean male and female proso..., ,

研究目标
成年个体体型常随大尺度环境梯度呈现规律性变化，形成生态地理渐变群（ecogeographic clines）。然而，体型渐变群的形式在不同分类群间存在差异，自然界中已观测到线性与非线性两种体型分布模式。目前针对非线性体型渐变群的研究较少，关于环境梯度如何相互作用以形成非线性渐变群的问题仍有待解答。本研究以分布广泛的海洋节肢动物美洲鲎（American horseshoe crab, Limulus polyphemus）为研究对象，检验了“温度与活动季长度可通过相乘性相互作用，形成穹顶状体型分布”这一假说。

研究区域
覆盖该物种的整个地理分布范围，包括美国14个州与墨西哥3个州。

研究方法
我们整合了来自超过49000只美洲鲎个体的环境数据与体型测量数据。针对每个研究区域，我们从文献中提取或基于原始数据进行计算……

数据收集
体型数据
我们检索了期刊论文、专著以及联邦与州级机构报告，以获取北美成熟成年美洲鲎的体型公开数据。此外，我们还获取了一份来自特拉华湾的未发表手稿数据，以及美国史密森学会（Smithsonian Institution）官网提供的佛罗里达印第安河泻湖区域美洲鲎的体型数据。我们补充了以下原创野外调查数据：美国纽约州石溪（2007年）、美国佐治亚州斯凯达维岛（2007年）与萨佩洛岛（2009年）、美国佛罗里达州海马礁（1995–1997年、2007–2009年），以及佛罗里达鲎监测公民科学项目（2015–2022年；Heres et al., 2021）的数据。

最终，我们整合了北美77个不同区域共49877只个体的体型测量数据，覆盖该物种的整个地理分布范围（美国14个州与墨西哥3个州）。针对每个区域，我们从文献中提取或基于原始数据计算得到了雄性与雌性的平均前体（proso...）。