Sleep and vigilance linked to melanism in wild barn owls

Abstract

Understanding the function of variation in sleep requires studies in the natural ecological conditions in which sleep evolved. Sleep has an impact on individual performance and hence may integrate the costs and benefits of investing in processes that are sensitive to sleep, such as immunity or coping with stress. Because dark and pale melanic animals differentially regulate energy homeostasis, immunity and stress hormone levels, the amount and/or organization of sleep may covary with melanin-based colour. We show here that wild, cross-fostered nestling barn owls (Tyto alba) born from mothers displaying more black spots had shorter non-REM (rapid eye movement) sleep bouts, a shorter latency until the occurrence of REM sleep after a bout of wakefulness and more wakefulness bouts. In male nestlings, the same sleep traits also correlated with their own level of spotting. Because heavily spotted male nestlings and the offspring of heavily spotted biological mothers switched sleep-wakefulness states more frequently, we propose the hypothesis that they could be also behaviourally more vigilant. Accordingly, nestlings from mothers displaying many black spots looked more often towards the nest entrance where their parents bring food and towards their sibling against whom they compete. Owlets from heavily spotted mothers might invest more in vigilance, thereby possibly increasing associated costs due to sleep fragmentation. We conclude that different strategies of the regulation of brain activity have evolved and are correlated with melanin-based coloration.

How Can We Study the Evolution of Animal Minds?

“…Mini embedded EcoG (electrocorticogram) recorders, called neuro-loggers, have been developed to track neural activities of free ranging wild animals. This method has been successfully adapted to different species: pigeons ( Vyssotski et al, 2006 , 2009 ), ostrich ( Lesku et al, 2011 ), sloths ( Rattenborg et al, 2008 ), sandpipers ( Lesku et al, 2012 ), or owls ( Scriba et al, 2014 ). The study on sandpipers illustrates that such tool can be used to link brain activity recorded in wild animals, for instance using individual brain rhythm characteristics, to fitness ( Lesku et al, 2012 ).…”

Sources of intraspecific variation in sleep behaviour of wild great tits

“…Studies on sleep and sleep deprivation indicate that sleep may function in cellular repair (Savage & West, 2007), memory consolidation, learning, synaptic plasticity (Stickgold & Walker, 2005), energy conservation (Siegel, 2005) and maintaining physical and cognitive performance (Koslowsky & Babkoff, 1992). However, sleep is in many ways an underexplored phenomenon in the field of behavioural ecology (Lesku et al, 2012;Scriba, Rattenborg, Dreiss, Vyssotski, & Roulin, 2014;Steinmeyer, Mueller, & Kempenaers, 2013). Sleep may be evolutionarily homologous across the animal kingdom (Rattenborg, MartinezGonzalez, & Lesku, 2009).…”

Genetic Color Morphs in the Eastern Mosquitofish Experience Different Social Environments in the Wild and Laboratory

“…This result is consistent with other studies that have shown that genetically determined melanic body color is associated with variation in aggression and other behaviors. This pattern has been found in fruit flies (Takahashi 2013), other fish (Kittilsen et al 2009), reptiles (Mafli et al 2011), birds (Roulin et al 2000;Scriba et al 2014), and mammals (Bubenik & Bubenik 1985;West & Packer 2002;Graipel et al 2014). Such behavioral differences might arise from pleiotropic effects of the alleles that determine melanic color.…”