Countergradient Variation: Adaptation to Seasonality in Fishes

增长能力之间的反比关系（即， 最大生长潜力）和生长季节的长度 最近在鱼类中发现了纬度梯度。 这种有趣的种内“逆梯度变异” 可能代表了一种广泛的适应性策略， 季节性环境。 主要利用大西洋银汉鱼， Menidia menidia作为模式生物，本项目将评估 选择力、进化反应和生理反应 纬度适应的机制。前提是 北部的快速增长是对一个国家的 强烈的季节性环境：即，一个大尺寸是 在漫长的冬季生存所必需的，但只有一个短暂的增长， 在这个季节里，你可以获得更大的尺寸。 的 理论预测，更快的增长只能发生在 还将测试一些其他生命历史函数的代价。 不同产地银汉鱼实验室原种的试验 纬度的目的是：1）确定身体的影响 大小、脂质储存和基因型对越冬存活的影响;和2） 能量获取和分配中遗传变异测试 各种代谢功能，如食品加工，生长， 游泳 和生殖性能。 结果将 有 对我们生命史理论知识的影响，资源 海洋生物对气候的反应 变化

An inverse relation between the capacity for growth (i.e. maximum growth potential) and length of the growing season over a latitudinal gradient has recently been discovered in fishes. This intriguing form of intraspecific "countergradient variation" may represent a widespread adaptive strategy for coping with seasonal environments. Using primarily the Atlantic silverside, Menidia menidia, as a model organism, this project will evaluate the selective forces, evolutionary responses, and physiological mechanisms underlying latitudinal adaptation. The premise is that rapid growth in the north is an evolutionary response to an intensely seasonal environment: i.e., one where large size is necessary to survive long winters, but where only a brief growing season is available in which to attain large size. The theoretical prediction that faster growth can occur only at the expense of some other life history function will also be tested. Experiments on laboratory stocks of silversides from different latitudes are designed to: 1) determine the influence of body size, lipid storage and genotype on overwinter survival; and 2) test for genetic variation in energy acquisition and allocation to various metabolic functions such as food processing, growth, swimming and reproductive performance. Results will have implications for our knowledge of life history theory, resource management, and the response of marine organisms to climate change.