Sex Determination in Japanese Quails (Coturnix japonica) Using Geometric Morphometrics of the Skull

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The study investigated whether there is a morphological difference between the shape of the female and male quail's skulls. For this purpose, 18 female and 21 male quails were used. After the skulls were obtained, their photographs were taken, and geometric analysis was performed. Dorsal (14 landmarks), caudal (8 landmarks), and ventral (13 landmarks) images of skulls were evaluated. As a result of the Principal Component Analysis (PCA), 28 principal components (PCs) were obtained for dorsal view, 16 PCs for caudal view, and 26 PCs for ventral view. PC1 (41.206%) for the caudal aspect explained the highest shape variation in terms of sex. It was seen that PC1 for dorsal view explained 33.046% and PC1 for ventral view explained 34.495% shape variation. For the dorsal view, the orbital pit of males was found to be deeper than females. The foramen magnum was narrower in female skulls. The lateral borders of the neurocranium were more pointed upwards in males. On ventral view, it was seen that male individuals had a wider skull in shape. Geometrically, it was determined that the male and female distinction was the best in the dorsal view. According to the dorsal view, only one male individual was found to be in the female group, and all other male individuals were completely separated from the females. After the dorsal view, the best distinction was seen ventrally. In the caudal examination, sexual discrimination was not fully seen. In this study, shape differences in quail's skulls were examined between sexes, and shape differences were revealed geometrically. In addition to traditional morphometry studies, it is thought that geometric analysis studies will add a useful perspective to the literature.