The study of phenotypic variation at the level of populations and species is central to understanding the processes that lead to evolutionary diversification. Triplefin fishes (Tripterygiidae) are a diverse and ecologically important family on New Zealand rocky reefs. This assemblage provides an opportunity to explore phenotype-environment relationships and the mechanisms responsible for the ecological speciation that is thought to have driven diversification in this clade. To test these relationships, we used two main approaches. Firstly, we used a geometric morphometric approach, and secondly, we used controlled rearing experiments in aquaria to examine the mechanism behind this phenotypic variation. The results showed that wild populations of the habitat generalist Forsterygion lapillum differed in body and fin morphology across a gradient in wave exposure in a region with extensive gene flow. Results of the tank experiments demonstrated that new recruits of F. lapillum from the same location that were raised in distinct water movement environments became morphologically distinct, whereas new recruits of F. lapillum from distinct water movement environments that were raised in identical conditions did not. The reciprocal rearing experiments, in conjunction with the morphological variation shown in wild individuals across the exposure gradient, indicate that plasticity is predominantly responsible for the phenotypic variation seen in F. lapillum populations in the Hauraki Gulf, New Zealand.

在种群和物种水平上研究表型变异对于理解导致进化多样化的过程至关重要。三鳍鱼（Tripterygiidae）是新西兰岩礁上的一个多样化且具有重要生态意义的家庭。这种组合提供了一个机会来探索表型-环境关系以及负责生态物种形成的机制，而生态物种形成被认为是推动了这个进化枝的多样化。为了测试这些关系，我们使用了两种主要方法。首先，我们使用了几何形态测量方法，其次，我们在水族箱中使用了受控饲养实验来检查这种表型变异背后的机制。结果表明，栖息地通才Forsterygion lapillum 的野生种群在具有广泛基因流动的区域中，在波浪暴露的梯度上，身体和鳍的形态不同。水族箱实验的结果表明，在不同的水运动环境中饲养的来自相同位置的F. lapillum 的新成员在形态上变得不同，而在相同条件下饲养的来自不同水运动环境的F. lapillum 的新成员没有。相互饲养实验，结合暴露梯度中野生个体的形态变异，表明可塑性是新西兰豪拉基湾F. lapillum种群表型变异的主要原因。