Offspring sex ratio in Eurasian Kestrel(Falco tinnunculus)with reversed sexual size dimorphism

Fisher's theory predicts equal sex ratios at the end of parental care if the cost associated with raising offspring of each sex is equal.However,sex ratios have important evolutionary consequences and are often biased for many factors.Reported sex ratios are often biased in raptors,which display various degrees of reversed sexual dimorphism,but there seems no consistent pattern in their offspring sex ratios.In this study,we investigated the offspring sex ratio of the Eurasian Kestrel(Falco tinnunculus) and tested whether the patterns of biased sex ratios were related to laying order,egg mass,hatching order,laying date or clutch size.The brood sex ratio of the Eurasian Kestrel(male) in eggs was 47.0%,not statistically biased from 0.5,but in fledglings it was 40.8%,significantly biased from 0.5(p = 0.029).At population level,both primary and secondary sex ratios did not depart from parity.We found that clutch size and egg mass affected the secondary brood sex ratio,i.e.,the larger the clutch size,the larger the number of males and eggs producing sons were heavier than eggs producing daughters.Laying date affected both the primary and secondary sex ratios,and laying earlier is associated with a greater proportion of males.

Evaluation of Frontal Sinus Index in Establishing Sex Dimorphism Using Three-Dimensional Cone Beam Computed Tomography in Northern Saudi Arabian Population

Purpose:Identification of sex of unknown people becomes important in situations of mass disaster.Previous studies have shown that morphological characteristic of frontal sinus is distinctive to particular individual and hence,literature suggests that it can be used in establishing identification of a person.However,few researches have concluded that,its use in detennining sexual dimorphism is limited.Aim:This study aimed to evaluate frontal sinus index using cone beam computed tomography(CBCT)and differentiate sex dimorphism based on the index obtained.Materials and Methods:A retrospective cross-sectional study was undertaken using three-dimensional-CBCT scans.By simple random sampling method,150 scans were selected,out of which 74 were of male and 76 were of female within the age group of20-64 years.The frontal sinus width and the height were measured,and the ratio was taken as frontal sinus index.This index was correlated to the differentiation of sex.Data were analyzed using SPSS,and sex dimorphism was assessed using discriminant function analysis.Results:The mean height of the frontal sinus in both males and females was 30.12±7.6 mm and 30.14±7.8 mm,respectively.The mean width of frontal sinus in males(13.39±3.6 mm)was slightly more than that of females(12.06±3 mm).Conclusion:The parameter frontal sinus index measured using CBCT was found to be a contributing factor in sex determination in forensic identification within the sample population.

Karyotypic Analysis of the Clipper Barb Enteromius callipterus (Boulenger 1907) from Tahoss Stream, Jos Plateau, Nigeria

The chromosomes of male and female individuals of Enteromius callipterus [1] were assessed in this study with the objective of determining the diploid chromosome and karyotype. The samples were obtained from the Tahoss River, Jos Plateau, and the assessment of the chromosomes was conducted using the conventional Giemsa staining technique. The study reveals that the male individual of E. callipterus has a diploid chromosome number of 2n = 50, the fundamental number of autosomal arms (NFa) of 82, and a karyotype formula of 2n = 14M + 4m + 32t. However, none of the spreads obtained for the female individuals were either equal to or below the common diploid chromosome number of 50 known for members of the genus. The two spreads presented here were of 2n equal to 54 and 58. Although sex dimorphism is rare within the genus, the present results suggest E. callipterus show sexual dimorphism at the chromosomal level.

Sex differences in anogenital distances and digit ratios in wild David＇s rock squirrels Sciurotamias davidianus

The prenatal hormonal environment plays an important role in organizing sex differences in the morphology, physiology and behavior of humans as well as other vertebrates. Currently, all related research on rodents has been focused on Myomorpha. This study presents data on sex differences in the anogenital distance （AGD） and the ratio of the second to the fourth digit length （2D：4D） from 44 wild David＇s rock squirrels Sciurotamias davidianus captured from the Qinling Mountains, China. This was the first study of a species from Sciuromorpha. The AGD as well as body mass are sexually dimorphic. There are no sex differences or lateral asymmetry in 2D：4D. Significant correlation was not found between AGD and 2D：4D for any paw. The findings indicate that 2D：4D may not be fixed or influenced by the prenatal steroidal environment in David＇s rock squirrels [Current Zoology 60 （2）： 180-185, 2014].