Ontogenetic Variation and Sexual Dimorphism of Beaks among Four Cephalopod Species Based on Geometric Morphometrics

• Published in: Animals
• Main Authors: Chao Wang, Zhou Fang
• Format: Article
• Language: English
• Published: MDPI AG 2023-02-01
• Subjects: cephalopods; beaks; ontogenetic variation; sexual dimorphism; geometric morphometrics; phenotypic plasticity
• Online Access: https://www.mdpi.com/2076-2615/13/4/752

Investigating the ontogenetic variation of biological individuals helps us to fully understand the characteristics of evolution. In order to explore the ontogenetic variation and sexual dimorphism of the beak shape in <i>Octopus minor</i>, <i>Uroteuthis edulis</i>, <i>Sepia esculenta</i> and <i>Sthenoteuthis oualaniensis</i> of the China’s coastal waters, the differences between immature and mature stages and the sex-linked differences in the beak shape and size were analyzed with geometric morphometrics methods in this study. The results of Procrustes analysis of variance, principal component analysis and multivariate regression showed that the shapes of the upper beaks of <i>O. minor</i>, <i>U. edulis</i> and <i>S. esculenta</i> differed significantly among various ontogenetic stages (<i>p</i> < 0.05). The shapes of the lower beaks of <i>U. edulis</i>, <i>S. esculenta</i> and <i>Sthenoteuthis oualaniensis</i> were also significantly different among various ontogenetic stages (<i>p</i> < 0.05). The results of thin-plate spline deformation grids showed that the beaks of the four cephalopod species presented different variation patterns. This study gives us basic beak geometry morphology information for <i>Octopus minor</i>, <i>Uroteuthis edulis</i>, <i>Sepia esculenta</i> and <i>Sthenoteuthis oualaniensis</i> present in China’s coastal waters. The ontogenetic differences in beak shape might be related to extrinsic factors (diet difference and intra and interspecific competition) in habitat.