个体生长对秘鲁外海茎柔鱼角质颚形态变化的影响

海洋生物的表型与其栖息环境密切相关，了解其与资源利用相关的表型特征有助于理解其资源利用方式及生态位特征。茎柔鱼广泛分布于东太平洋，是该海域生态系统的关键种，其个体形态受环境影响变化明显。为探究不同环境条件是否会对茎柔鱼的重要摄食器官角质颚的形态产生影响，本研究对东太平洋赤道海域加拉帕戈斯群岛东、西部两个群体共244尾茎柔鱼的角质颚进行了形态学分析。采用传统形态方法测量了角质颚的12项外部形态参数，并利用几何形态测量方法对其上、下角质颚图像分别设置20个地标点并进行数字化分析。结果显示，不同群体的茎柔鱼角质颚的11项外部形态参数均存在显著差异，但差异系数均小于1.28。几何形态分析显示，不同群体茎柔鱼角质颚的整体大小及形状均差异显著，并具有不同的异速生长模式，形状差异主要体现在上颚的喙部与侧壁、下颚的喙部与翼部。不同群体的上、下角质颚均具有较高的判别成功率，平均判别正确率分别为89.61%和85.88%。加拉帕戈斯群岛以东海域的茎柔鱼具有较小的角质颚、较弯曲和尖锐的喙部、较大的侧壁及较短较宽的翼部，可能与该栖息地的环境及食物类型有关。这些与资源利用相关的表型可塑性反映了茎柔鱼对于不同栖息环境的适应，有利于提高其生存能力。

Morphological characterization of striped seabream (Lithognathus mormyrus, Sparidae) in some Mediterranean lagoons

Phenotypic variation within a species can be associated with varying environmental conditions in their habitats. Understanding the variations in species’ phenotypes helps to understand their resource utilization and ecological niche. The jumbo squid, Dosidicus gigas, is a keystone species of the Eastern Pacific Ocean, which is widely distributed and exhibits large phenotypic variation under environmental influences. To investigate whether different environmental conditions lead to morphological changes in the beak of D. gigas, the animal’s important feeding apparatus, a total of 244 D. gigas’ beaks were collected from the eastern equatorial Pacific Ocean from Jun to August in 2017, 129 and 115 specimens were from the western and eastern waters of the Galapagos Archipelago, respectively. Traditional morphometrics and geometric morphometrics methods were applied to quantify the external morphology of the beak. A total of twelve external morphological parameters were measured through traditional morphometrics, and twenty landmarks were set on the one-side image of upper and lower beaks and digitized for geometric morphometrics analysis. The results showed that 11 external standard morphological parameters of beaks were significantly different between different cohorts except for upper hood length (UCLs) (P<0.05). Although the coefficients of difference were all less than 1.28. Geometric morphometric analysis showed significant differences (P<0.001) in the size and shape of upper and lower beaks between the two cohorts, with different allometric growth patterns. The morphological differences were mainly reflected in the rostrum and lateral wall of the upper beak, and the rostrum and wing of the lower beak. Stepwise discrimination analysis based on land-mark geometric morphometrics showed high success rates for both upper and lower beaks, which were 89.61% and 85.88%, respectively. D. gigas from the eastern waters had smaller beaks with more curved and sharper rostrum, larger lateral walls, and wider but shorter wings compared to those from the western waters, which may be attributed to the environmental conditions and food types of the habitat. Such resource allocation-related phenotypic plasticity could be considered as a response to the environmental characteristics of their habitats, which may likely facilitate their survival.