COUNTERGRADIENT VARIATION IN GROWTH-RATE - COMPENSATION FOR LENGTH OF THE GROWING-SEASON AMONG ATLANTIC SILVERSIDES FROM DIFFERENT LATITUDES
COUNTERGRADIENT VARIATION IN GROWTH-RATE - COMPENSATION FOR LENGTH OF THE GROWING-SEASON AMONG ATLANTIC SILVERSIDES FROM DIFFERENT LATITUDES
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DOI：
10.1007/bf00317554
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发表时间：
1990-01-01
期刊：
影响因子：
2.7
通讯作者：
PRESENT, TMC
中科院分区：
文献类型：
--
作者：
CONOVER, DO;PRESENT, TMC
生物如何适应温度和生长季节长度随纬度的差异？在沿着北美东海岸的大西洋银汉鱼（Menidia menidia）中，随着纬度的增加，第一生长季节的长度减少约2.5倍。然而，在第一个生长季节结束时，身体大小并没有下降。因此，高纬度的鱼在生长季节中一定比低纬度的鱼生长得更快。这种地理格局有其遗传基础。对来自六个不同地点的鱼的进化实验揭示了生长能力的纬度梯度（即，最大的增长潜力）。在随后的两个实验中，使用的鱼从新斯科舍省（NS），纽约（NY）和南卡罗来纳州（SC），已分别在一个共同的环境中饲养了几代，种群之间的增长率差异是非常显着的。结果表明，不同温度下，种群间的差异大小顺序为NS> NY> S，但种群间的差异因温度而异。高纬度鱼类的表现优于低纬度鱼类，主要是在低纬度鱼类在自然界中最常经历的高温下。这些结果表明，而不是被适应在低温下生长，从高纬度的鱼是适应在一年中的短暂间隔期间，当高温发生的生长速度的快速提升。选择生长速度的结果，从大小依赖的冬季死亡率：冬季生存的重要性是大的纬度增加，但生长季节的长度同时减少。最终的结果是增长率的反梯度变化，这种现象可能比目前认识到的要普遍得多。
How do organisms adapt to the differences in temperature and length of the growing season that occur with latitude? Among Atlantic siliverside (Menidia menidia) along the east coast of North America, the length of the first growing season declines by a factor of about 2.5 with increasing latitude. Yet body size at the end of the first growing season does not decline. High-latitude fish must, therefore, grow faster within the growing season than do low-latitute fish. This geographical pattern has a genetic basis. Laborratory experiments on fish from six different locations revealed a latitudinal gradient in the capcity for growth (i.e., maximum growth potential). In two subsequent experiments using fish from Nova Scotia (NS), New York (NY) and South Carolina (SC) that had been separately reared in a common environment for several generations, differences in growth rate among populations were highly significant. The rank order was NS > NY > S, but the difference among populations depended on temperature. High-latitude fish outperformed those from low latitudes primarily at the high temperatures that low-latitude fish would be expected to experience most often in nature. These results suggest that instead of being adapted for growth at low temperatures, fish from high latitudes are adapted for rapid elevation of growth rate during the brief interval of the year when high temperatures occur. Selection on growth rate results from size-dependent winter mortality: the importance to winter survival of being large increases with latitude but the length of the growing season simultaneously decreases. The end result is countergradient variation in growth rate, a phenomenon that may be much more widespread than currently recognized.