Phylogeny and biogeography of ratite birds inferred from DNA sequences of the mitochondrial ribosomal genes

The origin of the flightless ratite birds of the southern continents has been debated for over a century. Whether dispersal or vicariance (continental breakup) best explains their origin depends largely on their phylogenetic relationships. No consensus has been reached on this issue despite many morphological and molecular studies. To address this question further we sequenced a 2.8-kb region of mitochondrial DNA containing the ribosomal genes in representative ratites and a tinamou. Phylogenetic analyses indicate that Struthio (Africa) is basal and Rhea (South America) clusters with living Australasian ratites. This phylogeny agrees with transferrin and DNA hybridization studies but not with sequence analyses of some protein-coding genes. These results also require reevaluation of the phylogenetic position of the extinct moas of New Zealand. We propose a new hypothesis for the origin of ratites that combines elements of dispersal and vicariance.      

Non-random foraging in certain bird pests of field crops

Two systems of bird-crop interactions were studied to explain the between- and the within-field variation in the foraging pattern of bird pests in agro-ecosystems. Weaverbirds and munias select rice fields with greater vegetation complexity and not based on the resource status. Within a selected area the concentration of feeding birds was greater close to vegetation cover and decreased non-linearly with increase in distance. Certain structural features and earhead characters of rice plants predisposed particular varieties for intense grain predation by birds. In the parakeet-sunflower system the extent of damage among plants within a field was closely linked to the foraging pattern of parakeets. The extent of achene predation by parakeets was influenced by certain structural features of sunflower plants and not the resource load of each plant. Selective feeding on sunflower plants was governed by the predator vigilance pattern; parakeets prefer to feed on plants that offered better field of vision. The results suggest that the observed pattern of foraging by bird pests in agro-ecosystems is non-random and is dependent on factors favouring predator avoidance behaviour and not on resource maximization.     

On chip optofluidic low-pressure monitoring device

We present an on chip optofluidic surface deformable liquid Dove prism (LDP) based low-fluid flow pressure monitoring device. The unique design of the device in combination with liquid and soft solid enabled by the total internal reflection of light makes the sensor highly sensitive and compatible with the integration of a microfluidic and/or Lab-on-a-chip device. A layer-by-layer soft lithographic (LSL) and 3D printing technique are exploited to make the device. We have used Polydimethylsiloxane (PDMS) as the layer material and two variety of liquids (a) immersion oil (IO) and (b) di-iodomethane (DI) as refracting medium to construct the LDP sensor. Optical ray tracing simulation is performed to optimize the sensor. The pressure sensor shows sensitivity as high as ±28.5 mV per 50 Pa pressure with an error ± 2.5 mV and repeatability of ~99.56% at full scale. We have shown the applicability of the sensor by capturing and analyzing respiratory pressure signals of some human subjects at numerous conditions.