Sexual dimorphism in the carapace of mud crab (Scylla serrate, Forsskal, 1775) in Magallanes, Agusandel Norte using Geometric Morphometric Analysis

Abstract

The study was conducted mainly to describe and analyse the sexual dimorphism using carapace shape in both sexes of S. serrata collected from Magallanes, Agusandel Norte using geometric morphometrics as a tool. On the other hand, Landmark-based methods utilize biological equivalences on the homologous structures of an organism. It aims to note the position of important landmarks, amputating irrelevant data as to differences in size, rotation, and locations of the biomarker using Thin Plate Splice (TPS). This method was employed to discriminate differences between male and female and to describe various variations that occur in the form of biomarkers in response to its situations. A total of 60 individuals (30 males and 30 females) were subjected to relative warp analysis. Land-mark analysis was obtained using TPS series with 33 landmarks generated for each samples and loaded into tpsrelww32 to assess the distinction in the body shape between male and female S. serrata. Sexual dimorphism of S. serrata from Magallanes, Agusan del Norte can be seen between the two sexes, based on the MANOVA test that results to a relative significant difference that is presented and further visualized in the Canonical Variation Analysis (CVA) that produces scatter plot along the two canonical axes (X and Y axes), producing a separation of the two sexes.

Keywords

• sexual dimorphism
• geometric morphometics
• mud crab (Scylla serrate)
• Magallanes
• Agusandel Norte