Arsenault D J, Marchinko K B, Palmer A R
Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
Proc Biol Sci. 2001 Oct 22;268(1481):2149-54. doi: 10.1098/rspb.2001.1776.
Both spatial and temporal variation in environmental conditions can favour intraspecific plasticity in animal form. But how precise is such environmental modulation? Individual Balanus glandula Darwin, a common northeastern Pacific barnacle, produce longer feeding legs in still water than in moving water. We report here that, on the west coast of Vancouver Island, Canada, the magnitude and the precision of this phenotypic variation is impressive. First, the feeding legs of barnacles from protected bays were nearly twice as long (for the same body mass) as those from open ocean shores. Second, leg length varied surprisingly precisely with wave exposure: the average maximum velocities of breaking waves recorded in situ explained 95.6-99.5% of the variation in average leg length observed over a threefold range of wave exposure. The decline in leg length with increasing wave action was less than predicted due to simple scaling, perhaps due to changes in leg shape or material properties. Nonetheless, the precision of this relationship reveals a remarkably close coupling between growth environment and adult form, and suggests that between-population differences in barnacle leg length may be used for estimating differences in average wave exposure easily and accurately in studies of coastal ecology.
环境条件的空间和时间变化都可能有利于动物形态的种内可塑性。但这种环境调节有多精确呢？太平洋东北部常见的藤壶——达尔文藤壶（Balanus glandula），其个体在静水中比在流动水中长出更长的进食附肢。我们在此报告，在加拿大温哥华岛西海岸，这种表型变异的幅度和精确性令人印象深刻。首先，来自受保护海湾的藤壶的进食附肢（对于相同体重而言）几乎是来自开阔海洋海岸的藤壶的两倍长。其次，附肢长度随波浪暴露程度的变化惊人地精确：现场记录的碎波平均最大速度解释了在三倍波浪暴露范围内观察到的平均附肢长度变化的95.6 - 99.5%。由于简单的比例关系，附肢长度随波浪作用增加而下降的幅度小于预期，这可能是由于附肢形状或材料特性的变化。尽管如此，这种关系的精确性揭示了生长环境与成体形态之间非常紧密的耦合，并表明在沿海生态研究中，藤壶附肢长度的种群间差异可用于轻松且准确地估计平均波浪暴露程度的差异。
