Shape Analysis of Otoliths of Capoeta trutta (Heckel, 1843) and Capoeta umbla (Heckel, 1843) Species by Geometric Morphometry

Capoeta (C.) trutta (Heckel, 1843) and Capoeta umbla (Heckel, 1843) are the most common species living in the Tigris and Euphrates rivers. This study aimed analyze the shape of the otoliths of C. trutta and C. umbla fish from the Capoeta genus, which inhabit the Tigris River in Turkey. The geometric morphometric method was used to identify and compare the similarities and differences between these fish species. A total of 72 right otoliths, (for each species 36), were used. Geometric morphometric analyses were performed by marking semi-landmarks on the otoliths. When the data were examined, it was determined that the first principal component accounted for 25.15% of the total shape difference, while the first four principal components (PC1+PC2+PC3+PC4) accounted for 59.14% of the total shape difference. According to the regression analysis of shape over size, 9.2615% of shape can be predicted in terms of size by groups and it was determined as 26.0817% of shape according to PC1 (P: 0.0001), 7.1205% according to PC2 (P: 0.0233) and 10.2255 (P: 0.0051) according to PC3 can be predicted. According to the cross-validation score, 7 (19.44%) samples from C. trutta and 4 (11.11%) samples from C. umbla were involved in the opposite group, and these results showed that the two groups had a successful grouping (at least 80%) according to the shape. Consequently, it is thought that the data of the present study can be reference data for many disciplines, especially the taxonomic classification of the species in question.