ABSTRACT: In 2014, the Atlantic mud fiddler crab Uca pugnax was found 80 km north of its previously known northern range limit. Two years before this shift was noted, we collected a total of 781 male and female specimens from 6 populations along a latitudinal transect extending from Wareham, Massachusetts (41.7615°N), to Tybee Island, Georgia (32.0139°N), USA. By assessing latitudinal and seasonal patterns in the hepatosomatic index (HSI; a measure of stored energy) and the reproductive status of females, we sought to determine whether adult physiological and reproductive limits might slow the northern expansion of U. pugnax. We did not find a latitudinal cline for HSI, suggesting that U. pugnax is a thermal generalist; however, both males and females in the southern part of the range showed greater seasonal fluctuations in HSI compared to northern conspecifics. Across the range, ovigerous females had a significantly reduced HSI, revealing the cost of reproduction. Ovigerous females were found in the May 2013 collection in Massachusetts before ocean conditions were permissible for larval development and earlier than previously reported for this species. U. pugnax is expected to closely track warming conditions in the Northwest Atlantic because adults in northern populations are able to maintain energy stores comparable to that of their southern conspecifics, and they release planktonic larvae in early spring, maximizing their dispersal potential.

中文翻译：

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招潮蟹Uca pugnax能量储量的季节性和纬度变化：对气候变化的响应意义

摘要：2014年，大西洋泥提琴蟹Uca pugnax被发现在其先前已知的北部范围以北80公里处。在注意到这种转变的两年之前，我们从一个横向样带收集了总共781个男性和女性标本，这些横向样带从马萨诸塞州的Wareham（41.7615°N）延伸到美国乔治亚州的Tybee Island（32.0139°N）。通过评估肝体指数（HSI；储存能量的量度）和女性生殖状态的纬度和季节模式，我们试图确定成年的生理和生殖极限是否可能会减慢垂尾U的北部扩张。我们没有发现恒指的纬度指数，这暗示了U. pugnax是一名热心通才；然而，与北部同种异体相比，该范围南部的雄性和雌性均显示出恒指的季节性波动更大。在整个范围内，雌雄同体的HSI显着降低，显示出繁殖成本。2013年5月在马萨诸塞州发现了雌雄同体的雌性，当时允许幼体发育的海洋条件是允许的，并且早于该物种的先前报道。由于北部地区的成年人能够维持与其南部同种物种相当的能量储存，并且它们在早春释放出浮游性幼虫，从而最大限度地发挥其散布潜力，因此，U。pugnax有望密切追踪西北大西洋的变暖情况。