Adaptive and maladaptive consequences of “matching habitat choice:” lessons from a rapidly-evolving butterfly metapopulation

Relationships between biased dispersal and local adaptation are currently debated. Here, I show how prior work on wild butterflies casts a novel light on this topic. “Preference” is defined as the set of likelihoods of accepting particular resources after encountering them. So defined, butterfly oviposition preferences are heritable habitat adaptations distinct from both habitat preference and biased dispersal, but influencing both processes. When a butterfly emigrates after its oviposition preference begins to reduce realized fecundity, the resulting biased dispersal is analogous to that occurring when a fish emigrates after its morphological habitat adaptations reduce its feeding rate. I illustrate preference-biased dispersal with examples from metapopulations of Melitaea cinxia and Euphydryas editha. E. editha were feeding on a well-defended host, Pedicularis, when humans created patches in which Pedicularis was killed and a less-defended host, Collinsia, was rendered phenologically available. Patch-specific natural selection favoured oviposition on Collinsia in logged (“clearing”) patches and on Pedicularis in undisturbed open forest. Quantitative variation in post-alighting oviposition preference was heritable, and evolved to be consistently different between patch types. This difference was driven more by biased dispersal than by spatial variation of natural selection. Insects developing on Collinsia in clearings retained adaptations to Pedicularis in clutch size, geotaxis and oviposition preference, forcing them to choose between emigrating in search of forest habitats with Pedicularis or staying and failing to find their preferred host. Insects that stayed suffered reduction of realized fecundity after delayed oviposition on Collinsia. Those that emigrated suffered even greater fitness penalty from consistently low offspring survival on Pedicularis. Paradoxically, most emigrants reduced both their own fitness and that of the recipient populations by dispersing from a benign natal habitat to which they were maladapted into a more demanding habitat to which they were well-adapted. “Matching habitat choice” reduced fitness when evolutionary lag rendered traditional cues unreliable in a changing environment

Insulator-based dielectrophoresis for fouling suppression in submerged membranes bioreactors: Impact of insulators shape and dimensions

The application of insulator-based dielectrophoresis (iDEP) has the potential to enhance membrane fouling suppression in submerged membrane bioreactors without extra energy consumption. In this study, the effect of the insulators shapes and sizes within the interidigitated electrodes (IDE) configuration was investigated for a better dielectrophoresis (DEP) force with a better membrane fouling suppression. Three circular insulators CS 1, CS 1.5 and CS 2 with diameters of 1 mm, 1.5 mm and 2 mm, respectively, were tested. A 2 mm side square section insulator SS 2 was also examined. The numerical simulation results show that the DEP force extension is greater with a similar diameter as the excited electrodes (2 mm in this study) when using circular insulators. The use of square section insulator (SS 2) increases the overall electric field gradient squared (?|E|2) by 16% compared to the 2 mm circular insulator (CS 2). The square section insulator also extends the dielectrophoresis (DEP) force field more uniformly across the membrane surface while generating sufficient force to move the suspended solids away from the membrane. The experimental investigation verified the theoretical simulation prediction and demonstrated that SS 2 membrane modules provide longer membrane service time by maintaining a normalized permeate flux of 55% more than the circular section membrane modules, with a maximum intensification factor of 14 at a 220 V voltage and 50 Hz with a transmembrane pressure of 0.1 bar.This research is made possible by NPRP award (NPRP7-089-2-044) from Qatar National Research Fund (QNRF)Scopu