The importance of metabolic rate and/or spiracle modulation for saving respiratory water is contentious. One major explanation for gas exchange pattern variation in terrestrial insects is to effect a respiratory water loss (RWL) saving. To test this, we measured the rates of CO2 and H2O release ( and , respectively) in a previously unstudied, mesic cockroach, Aptera fusca, and compared gas exch...

We assessed respiratory and cutaneous water loss in trained tippler pigeons (Columba livia) both at rest and in free flight. In resting pigeons, exhaled air temperature T(ex) increased with ambient air temperature T(a) (T(ex)=16.3+0.705T(a)) between 15 degrees C and 30 degrees C, while tidal volume V(T) (V(T)=4.7+/-1.0 ml, mean +/- S.D. at standard temperature and pressure dry) and breathing fr...

Respiratory water loss (RWL) in insects showing continuous emission of CO(2) is poorly studied because few methodologies can measure it. Comparisons of RWL between insects showing continuous and discontinuous gas exchange cycles (DGC) are therefore difficult. We used two recently developed methodologies (the hyperoxic switch and correlation between water-loss and CO(2) emission rates) to compar...

drought stress is the most important factor that reduces yield in crops including chickpea and causes some changes in seed composition. this study was performed in order to evaluate the effects of drought stress and starter nitrogen fertilizer on four cultivars of chickpea. experiment was performed in a split-factorial using randomized complete block design with three replications. drought stre...

This study was carried out to evaluate the effect of soil application of humic acid on growth and physiological indices of pistachio seedlings ("Badami Zarand" rootstock) under drought stress. This experiment was arranged as a completely randomized design with three replications in greenhouse conditions. The experimental treatments consisted of humic acid (0, 30 and 60 gr in 4 kg-1 s...

The hygric hypothesis postulates that insect discontinuous gas exchange cycles (DGCs) are an adaptation that reduces respiratory water loss (RWL), but evidence is lacking for reduction of water loss by insects expressing DGCs under normal ecological conditions. Larvae of Erynnis propertius (Lepidoptera: Hesperiidae) naturally switch between DGCs and continuous gas exchange (CGE), allowing flow-...

The discontinuous gas exchange cycle (DGC) of insects and other tracheate arthropods temporally decouples oxygen uptake and carbon dioxide emission and generates powerful concentration gradients for both gas species between the outside world and the tracheal system. Although the DGC is considered an adaptation to reduce respiratory water loss (RWL) - the "hygric hypothesis" - it is absent from ...

We measured respiratory water loss (RWL) and cutaneous water loss (CWL) of 12 species of passerine birds, all from a temperate environment, and related their CWL to classes of lipids within the stratum corneum (SC). We purposed to gain insight into the generality of patterns of CWL in birds that have been generated mostly from studies on species from deserts, and we addressed the hypothesis tha...

The significance of discontinuous gas-exchange cycles (DGC) in reducing respiratory water loss (RWL) in insects is contentious. Results from single-species studies are equivocal in their support of the classic 'hygric hypothesis' for the evolution of DGC, whereas comparative analyses generally support a link between DGC and water balance. In this study, we investigated DGC prevalence and charac...