Conservatism and adaptability during squirrel radiation : what is mandible shape telling us?

SYNTHESYS Project from the European Community Research Infrastructure (NL-TAF-4084)Both functional adaptation and phylogeny shape the morphology of taxa within clades. Herein we explore these two factors in an integrated way by analyzing shape and size variation in the mandible of extant squirrels using landmark-based geometric morphometrics in combination with a comparative phylogenetic analysis. Dietary specialization and locomotion were found to be reliable predictors of mandible shape, with the prediction by locomotion probably reflecting the underlying diet. In addition a weak but significant allometric effect could be demonstrated. Our results found a strong phylogenetic signal in the family as a whole as well as in the main clades, which is in agreement with the general notion of squirrels being a conservative group. This fact does not preclude functional explanations for mandible shape, but rather indicates that ancient adaptations kept a prominent role, with most genera having diverged little from their ancestral clade morphologies. Nevertheless, certain groups have evolved conspicuous adaptations that allow them to specialize on unique dietary resources. Such adaptations mostly occurred in the Callosciurinae and probably reflect their radiation into the numerous ecological niches of the tropical and subtropical forests of Southeastern Asia. Our dietary reconstruction for the oldest known fossil squirrels (Eocene, 36 million years ago) show a specialization on nuts and seeds, implying that the development from protrogomorphous to sciuromorphous skulls was not necessarily related to a change in diet

Lignin modified PVDF membrane with antifouling properties for oil filtration

Lignin is a sustainable chemical that can be extracted from a wide range of lignocellulosic biowaste. It was blended into polymeric membranes to improve membrane morphology for filtration. Lignin dissolved in NaOH solution can be coated on different substrates to improve the surface hydrophilicity. In this work, the polyvinylidene fluoride (PVDF) membrane was coated with lignin to improve the filtration of oily water. Lignin was dissolved in NaOH solution with varied alkaline concentration (0.25–1.50 wt%) and lignin concentration (0.25–1.00 wt%). The PVDF membrane degraded in the highly alkaline solution, but the increasing lignin content reduced the membrane pore size for the effective rejection of oil emulsion. The PVDF membrane modified with 0.75 wt% of lignin in 0.5 wt% of NaOH solution attained a permeate flux about 70 L⋅m-2⋅h-1, but a slightly lower permeate flux of 55 L⋅m-2⋅h-1 was recorded after immersed in alkaline solution 12 h. The lignin modified membrane rejected up to 99.30% of oil, while the neat PVDF membrane only rejected 83.30% of oil. The lignin modified membrane showed slightly lower but stable flux than the neat PVDF membrane due to the reduction of membrane fouling