Postnatal development of lateralized motor preference in the African grey parrot (Psittacus erithacus)

Extra food provisioning does not affect behavioural lateralization in nestling lesser kestrels

Costs and benefits of brain lateralization may depend on environmental conditions. Growing evidence indicates that the development of brain functional asymmetries is adaptively shaped by the environmental conditions experienced during early life. Food availability early in life could act as a proxy of the environmental conditions encountered during adulthood, but its potential modulatory effect on lateralization has received little attention. We increased food supply from egg laying to early nestling rearing in a wild population of lesser kestrels Falco naumanni, a sexually dimorphic raptor, and quantified the lateralization of preening behaviour (head turning direction). As more lateralized individuals may perform better in highly competitive contexts, we expected that extra food provisioning, by reducing the level of intra-brood competition for food, would reduce the strength of lateralization. We found that extra food provisioning improved nestling growth, but it did not significantly affect the strength or direction of nestling lateralization. In addition, maternal body condition did not explain variation in nestling lateralization. Independently of extra food provisioning, the direction of lateralization differed between the sexes, with female nestlings turning more often towards their right. Our findings indicate that early food availability does not modulate behavioural lateralization in a motor task, suggesting limited phenotypic plasticity in this trait.

Melanism is related to behavioural lateralization in nestling barn owls

Behavioural laterality is a commonly observed phenomenon in many species suggesting there might be an advantage of using dominantly one side over the other for certain tasks. Indeed, lateralized individuals were often shown to be more successful in cognitive tasks compared to non-lateralized conspecifics. However, stressed individuals are also often, but not always, more strongly lateralized. Because barn owl (Tyto alba) females displaying larger black spots on the tip of their ventral feathers produce offspring that are more resistant to a variety of environmental stressful factors, we examined whether laterality is associated with melanin-based coloration. We recorded whether nestlings use more often the right or left foot to scratch their body and whether they preen more often one side of the body or the other using their bills. We found that the strength of lateralization of preening and scratching was less pronounced in individuals born from heavily spotted mothers. This result might be explained by plumage-related variation in the ability to resist stressful rearing conditions.

Perspectives on asymmetry: the Erickson Lecture

Topics discussed include asymmetry of the brain; prosopagnosia with asymmetric involvement; the blaspheming brain; effects of the numbers of X chromosomes on brain asymmetry; normal facial asymmetry; kissing asymmetry; left- and right-handedness; left-sided baby cradling; Nodal signaling and left/right asymmetry; primary cilium and left/right asymmetry in zebrafish; right/left asymmetry in snails; species differences in Shh and Fgf8; primary cilium in vertebrate asymmetry; Hedgehog signaling on the cilium; Wnt signaling on the cilium; situs solitus, situs inversus, and situs ambiguus (heterotaxy); ciliopathies; right-sided injuries in trilobites; unilateral ocular use in the octopus; fiddler crabs; scale-eating cichlids; narwhals; left-footed parrots; asymmetric whisker use in rats; and right-sided fatigue fractures in greyhounds.