Dmrt1 polymorphism covaries with sex-determination patterns in Rana temporaria.

Patterns of sex-chromosome differentiation and gonadal development have been shown to vary among populations of Rana temporaria along a latitudinal transect in Sweden. Frogs from the northern-boreal population of Ammarnäs displayed well-differentiated X and Y haplotypes, early gonadal differentiation, and a perfect match between phenotypic and genotypic sex. In contrast, no differentiated Y haplotypes could be detected in the southern population of Tvedöra, where juveniles furthermore showed delayed gonadal differentiation. Here, we show that Dmrt1, a gene that plays a key role in sex determination and sexual development across all metazoans, displays significant sex differentiation in Tvedöra, with a Y-specific haplotype distinct from Ammarnäs. The differential segment is not only much shorter in Tvedöra than in Ammarnäs, it is also less differentiated and associates with both delayed gonadal differentiation and imperfect match between phenotypic and genotypic sex. Whereas Tvedöra juveniles with a local Y haplotype tend to ultimately develop as males, those without it may nevertheless become functional XX males, but with strongly female-biased progeny. Our findings suggest that the variance in patterns of sex determination documented in common frogs might result from a genetic polymorphism within a small genomic region that contains Dmrt1. They also substantiate the view that recurrent convergences of sex determination toward a limited set of chromosome pairs may result from the co-option of small genomic regions that harbor key genes from the sex-determination pathway

Pattern of growth and utilization of abdominal fat bodies during larval development and metamorphosis in five South Indian anurans

The tadpoles of Rana tigrina, Rana cyanophlyctis, Rana curtipes, Polypedatus maculatus and Bufo melanostictus grew in size (mass and snout vent length of.SVL) progressively until metamorphic climax. The abdominal fat bodies first appeared in stages 25-30; and accumulation/utilization of fat during larval development and metamorphosis varied with the species. In B. melanostictus; fat bodies were barely seen. In laboratory-reared R. curtipes, body weight and fat body mass were better developed than in the wild caught. The amount of fat deposition was related to the duration of metamorphosis in the various species studied. The findings thus show that the size of fat bodies in the larval anurans is correlated with the body mass, SVL as well as duration of metamorphosis

Demography of fan-throated lizard, Sitana ponticeriana (Cuvier) in a cotton field in Dharwad district of Karnataka state, India

The demographic studies on Sitana ponticeriana show that the species is abundant in Gabbur village. The lizards exhibited a diurnal variation in their activity pattern (basking, foraging, seeking refuge, etc.). They were active in the morning hours when air temperature was ≤ 33° C and census yielded maximum numbers (45 ± 2.19 in 18,748 sq m or ~ 1.9 ha area). The study provides a pilot index as well as a reliable and accurate methodology for population survey of the lizard. The pilot index is essential for any large scale monitoring project and population trend analysis in future

Does temporal variation in predation risk affect antipredator responses of larval Indian Skipper Frogs (<i>Euphlyctis cyanophlyctis</i>)?

Predation risk varies on a moment-to-moment basis, through day and night, lunar and seasonal cycles, and over evolutionary time. Hence, it is adaptive for prey animals to exhibit environment-specific behaviour, morphology, and (or) life-history traits. Herein, the effects of temporally varying predation risk on growth, behaviour, morphology, and life-history traits of larval Indian Skipper Frogs (Euphlyctis cyanophlyctis (Schneider, 1799)) were studied by exposing them to no risk, continuous, predictable, and unpredictable risks at different time points. Our results show that larval E. cyanophlyctis could learn the temporal pattern of risk leading to weaker behavioural responses under predictable risk and stronger responses to unpredictable risk. Temporally varying predation risk had a significant impact on tadpole morphology. Tadpoles facing continuous risk had narrow tail muscles. Tadpoles facing predictable risk during the day were heavy with wide and deep tail muscles, whereas those facing predictable risk at night had long tails. Tadpoles facing unpredictable risk were heavy with narrow tail muscles. Metamorphic traits of E. cyanophlyctis were also affected by the temporal variation in predation risk. Tadpoles facing predictable risk during the day emerged at the largest size. However, tadpoles facing predictable risk at night and unpredictable risk metamorphosed earlier, whereas those facing continuous risk metamorphosed later. </jats:p