Strength and cost of an induced immune response are associated with a heritable melanin‐based colour trait in female tawny owls

Abstract

Summary 1.Melanin pigments provide the most widespread source of coloration in vertebrates, but the adaptive function of such traits remains poorly known. 2.In a wild population of tawny owls ( Strix aluco ), we investigated the relationships between plumage coloration, which varies continuously from dark to pale reddish, and the strength and cost of an induced immune response. 3. The degree of reddishness in tawny owl feather colour was positively correlated with the concentration of phaeomelanin and eumelanin pigments, and plumage coloration was highly heritable (h 2 = 0·93). No carotenoids were detected in the feathers. 4. In mothers, the degree of melanin-based coloration was associated with antibody production against a vaccine, with dark reddish females maintaining a stronger level of antibody for a longer period of time compared to pale reddish females, but at a cost in terms of greater loss of body mass. 5. A cross-fostering experiment showed that, independent of maternal coloration, foster chicks reared by vaccinated mothers were lighter than those reared by nonvaccinated mothers. Hence, even though dark reddish mothers suffered a stronger immune cost than pale reddish mothers, this asymmetric cost was not translated to offspring growth. 6. Our study suggests that different heritable melanin-based colorations are associated with alternative strategies to resist parasite attacks, with dark reddish individuals investing more resources towards the humoral immune response than lightly reddish conspecifics.

Association between melanism, physiology and behaviour: A role for the melanocortin system

“…For instance, when exposed to food deprivation laboratory animals usually decrease the expression of the POMC gene (Myers et al, 2005;Dallman et al, 1999;Bertile et al, 2003;Schwartz and Porte, 2005; but see Kappeler et al, 2004). We carried out a study to investigate whether environmentally-induced variation in POMC gene expression differs between individuals displaying different degrees of melaninbased coloration (Gasparini et al, 2009). We considered the tawny owl (Strix aluco) because conspecifics vary in the degree of pheomelanin-based coloration, some individuals displaying a dark reddish plumage and others a non-reddish coloration.…”

Effects of corticosterone on innate and humoral immune functions and oxidative stress in barn owl nestlings

“…The analyses were run with an enzyme-linked immunoabsorbent assay [ELISA 'sandwich' (Crowther, 2001;Gasparini et al, 2009). As solid phase we used microtitre plates with 8ϫ12 wells.…”

Sex- and melanic-specific variations in the oxidative status of adult tawny owls in response to manipulated reproductive effort

“…Secondly, tawny owls show continuous variation in melaninbased plumage coloration (from light to dark reddish; for pictures, see Da Silva et al, 2013), the expression of which is strongly genetically controlled and not sensitive, or only weakly so, to environmental conditions (Brommer et al, 2005;Gasparini et al, 2009;Emaresi et al, 2013). Interestingly, differently coloured adult males display alternative trade-off resolution and life histories (Emaresi et al, , 2014.…”