Group size, sex and age composition of chital (Axis axis) and sambar (Rusa unicolor) in a deciduous habitat of Western Ghats

Knowledge of the social structure of a population is important for a range of fundamental and applied purposes. Group characteristics and population structure of chital (Axis axis) and sambar (Rusa unicolor) were studied in a deciduous habitat of Mudumalai Tiger Reserve, Western Ghats, India, during 2008-2009. Vehicle transects were monitored monthly to gather information on group-size and age-sex composition of chital and sambar. The average mean group size and crowding for chital and sambar was 13.1 ± 0.5 (n = 1020), 3.6 ± 0.2 (n = 377) and 33.3, 11.0 respectively. The average adult male:adult female:fawn ratio was 63.4:100:22.3 (n = 9391) and 43.9:100:23.7 (n = 1023) in chital and sambar respectively. The mean group size of chital and sambar varied significantly between seasons (Kruskal-Wallis test, p = <0.001). Peak fawning season was observed from February to May for chital and May to August for sambar. Group's sex-age composition influenced group formation in both species between seasons at different level. Adult male and fawn were the important predicting variables of change in group size. Skewed female sex ratio was probably due to selective male predation by large predators. Although fawning occurred throughout the year, both species showed seasonality in fawning. The above mentioned patterns differed between species depending upon their ecological adaptation in foraging strategies and habitat preference.     

Shape and function of the Bicoid morphogen gradient in dipteran species with different sized embryos

The Bicoid morphogen evolved approximately 150 MYA from a Hox3 duplication and is only found in higher dipterans. A major difference between dipteran species, however, is the size of the embryo, which varies up to 5-fold. Although the expression of developmental factors scale with egg length, it remains unknown how this scaling is achieved. To test whether scaling is accounted for by the properties of Bicoid, we expressed eGFP fused to the coding region of bicoid from three dipteran species in transgenic Drosophila embryos using the Drosophila bicoid cis-regulatory and mRNA localization sequences. In such embryos, we find that Lucilia sericata and Calliphora vicina Bicoid produce gradients very similar to the endogenous Drosophila gradient and much shorter than what they would have produced in their own respective species. The common shape of the Drosophila, Lucilia and Calliphora Bicoid gradients appears to be a conserved feature of the Bicoid protein. Surprisingly, despite their similar distributions, we find that Bicoid from Lucilia and Calliphora do not rescue Drosophila bicoid mutants, suggesting that that Bicoid proteins have evolved species-specific functional amino acid differences. We also found that maternal expression and anteriorly localization of proteins other than Bcd does not necessarily give rise to a gradient; eGFP produced a uniform protein distribution. However, a shallow gradient was observed using eGFP-NLS, suggesting nuclear localization may be necessary but not sufficient for gradient formation.