Iman Alinezhadi, Nastaran Heidari, Hossein Javanbakht,
Volume 7, Issue 3 (11-2020)
Abstract
Sexual dimorphism in the ratio of digits length is a morphological feature resulted from the interaction between sex hormones and prenatal Hox genes, the latter is known to control the development of both limbs and genitals. The status of this trend and ratios have been investigated in various animal groups, including humans, other mammals, birds, reptiles, and amphibians. In this study, the body length and sexual dimorphism in the second-to-fourth, second-to-third and third-to-fourth digit lengths ratios (i.e., 2D:3D, 2D:4D, 3D:4D) of left fore and hind limbs were investigated in 54 specimens of toads collected from the northern Iran, including Bufo viridis (16 males and 19 females) and Pelobates syriacus (10 males and 9 females). In addition, the body length of the studied specimens were recorded. The results showed that the average body length (SVL) of female individuals of Pelobates syriacus was higher than those in males, which was found to be statistically significant (P≤0.05). Meanwhile, the average body length (SVL) of female individuals of Bufo viridis was found to be higher than those in males, however, the difference was not statistically significant. No sexual dimorphism was detected in the second-to-fourth, second-to-third and third-to-fourth digit lengths ratios of left fore and hind limbs between the male and female undividuals of Bufo viridis. However, the second-to-fourth digit ratio (2D:4D) in Pelobates syriacus species were found to be significantly different (P=0.040) between the male and female individuals, as the ratio was higher in males than females. Therefore, it could be concluded that the sexual dimorphism in 2D:4D of Pelobates syriacus species is consistent with those in most amphibians and diapsids.
Nastaran Heidari,
Volume 8, Issue 1 (6-2021)
Abstract
Finger length ratios are organized during embryonic development of fingers as they exposed to sex steroid hormones, and may show varying degrees of sexual dimorphism between males and females in different animal groups. Among all the finger length ratios calculated in a sample, the ratio between the second to fourth fingers (2D: 4D) is the most important one. In this study, the 2D:4D ratios in both sides of the body (right and left) in all limbs were investigated to determine if sexual dimorphism is present in the 2D: 4D ratios in 44 specimens studied (20 males and 24 females) of Acanthodactylus blanfordi. Other morphological traits of the two sexes were also examined (23 metric and meristic traits), as a result, sexual dimorphism was observed in five metric and meristic morphological traits. In terms of the ratio of the size of the fingers and toes, sexual dimorphism in the length of the fingers was observed only in 2D: 4D on the right side of the body in forelimbs and hindlimbs. The value of this trait was higher in males than females and this difference was statistically significant P ≤0.05).
