Pulgar Jose M, Bozinovic Francisco, Ojeda F Patricio
Center for Advanced Studies in Ecology and Biodiversity and Departamento de Ecología, Pontificia Universidad Católica de Chile, Santiago, 6513677, Chile.
Oecologia. 2005 Feb;142(4):511-20. doi: 10.1007/s00442-004-1755-4. Epub 2004 Dec 24.
Geographic variability in the physiological attributes of widely distributed species can be a result of phenotypic plasticity or can reflect evolutionary responses to a particular habitat. In the field, we assessed thermal variability in low and high intertidal pools and the distribution of resident fish species Scartichthys viridis and transitory Girella laevifrons along this vertical intertidal gradient at three localities along the Chilean coast: Antofagasta (the northernmost and warmest habitat), Carrizal Bajo (central coast) and Las Cruces (the southernmost and coldest habitat). In the laboratory, we evaluated the thermal sensitivity of fish captured from each locality. The response to temperature was estimated as the frequency of opercular movements and as thermal selectivity in a gradient; the former being a indirect indicator of energy costs in a particular environment and the latter revealing differential occupation of habitat. Seawater temperature in intertidal pools was greatest at Antofagasta, and within each site was greatest in high intertidal pools. The two intertidal fish species showed opposite patterns of local distribution, with S. viridis primarily inhabiting the lower sectors of the intertidal zone, and G. laevifrons occupying the higher sectors of the intertidal zone. This pattern was consistent for all three localities. Locality was found to be a very important factor determining the frequency of opercular movement and thermal selectivity of both S. viridis and G. laevifrons. Our results suggest that S. viridis and G. laevifrons respond according to: (1) the thermal history of the habitat from which they came, and (2) the immediate physical conditions of their habitat. These results suggest local adaptation rather than plasticity in thermoregulatory and energetic mechanisms.
分布广泛的物种生理属性的地理变异性可能是表型可塑性的结果，也可能反映了对特定栖息地的进化反应。在野外，我们评估了低潮间带和高潮间带水池的热变异性，以及常驻鱼类物种绿鳍鱼（Scartichthys viridis）和短暂出现的光脸吉列鲷（Girella laevifrons）在智利海岸三个地点沿这个垂直潮间带梯度的分布：安托法加斯塔（最北部且最温暖的栖息地）、卡里扎尔巴霍（中部海岸）和拉斯克鲁塞斯（最南部且最寒冷的栖息地）。在实验室中，我们评估了从每个地点捕获的鱼类的热敏感性。对温度的反应通过鳃盖运动频率和梯度中的热选择性来估计；前者是特定环境中能量消耗的间接指标，后者揭示了栖息地的差异占据情况。潮间带水池的海水温度在安托法加斯塔最高，并且在每个地点内，高潮间带水池的温度最高。这两种潮间带鱼类呈现出相反的局部分布模式，绿鳍鱼主要栖息在潮间带的较低区域，而光脸吉列鲷占据潮间带的较高区域。这种模式在所有三个地点都是一致的。发现地点是决定绿鳍鱼和光脸吉列鲷鳃盖运动频率和热选择性的一个非常重要的因素。我们的结果表明，绿鳍鱼和光脸吉列鲷的反应依据：（1）它们所来自栖息地的热历史，以及（2）其栖息地的即时物理条件。这些结果表明在体温调节和能量机制方面是局部适应而非可塑性。
