Multivariate heredity of melanin-based coloration, body mass and immunity

Abstract

The genetic covariation among different traits may cause the appearance of correlated response to selection on multivariate phenotypes. Genes responsible for the expression of melanin-based color traits are also involved in other important physiological functions such as immunity and metabolism by pleiotropy, suggesting the possibility of multivariate evolution. However, little is known about the relationship between melanin coloration and these functions at the additive genetic level in wild vertebrates. From a multivariate perspective, we simultaneously explored inheritance and selection of melanin coloration, body mass and phytohemagglutinin (PHA)-mediated immune response by using long-term data over an 18-year period collected in a wild population of the common kestrel Falco tinnunculus. Pedigree-based quantitative genetic analyses showed negative genetic covariance between melanin-based coloration and body mass in male adults and positive genetic covariance between body mass and PHA-mediated immune response in fledglings as predicted by pleiotropic effects of melanocortin receptor activity. Multiple selection analyses showed an increased fitness in male adults with intermediate phenotypic values for melanin color and body mass. In male fledglings, there was evidence for a disruptive selection on rump gray color, but a stabilizing selection on PHA-mediated immune response. Our results provide an insight into the evolution of multivariate traits genetically related with melanin-based coloration. The differences in multivariate inheritance and selection between male and female kestrels might have resulted in sexual dimorphism in size and color. When pleiotropic effects are present, coloration can evolve through a complex pathway involving correlated response to selection on multivariate traits.

Old males reduce melanin‐pigmented traits and increase reproductive outcome under worse environmental conditions in common kestrels

“…; Kim et al. ), the role of environmental variance in the expression of melanin‐based traits is striking (Fargallo et al. ; Vergara et al.…”

“…; Kim et al. ). To explore the environmental influence, we used the abundance of common voles Microtus arvalis as a proxy of environmental variation, since the abundance of breeding kestrels in our population is sensitive to the interannual fluctuation of vole density (Fargallo et al.…”

Condition‐dependence, pleiotropy and the handicap principle of sexual selection in melanin‐based colouration

“…Cross‐fostering experiments in the barn owl ( Tyto alba ) (Roulin & Ducrest, ) and the tawny owl ( Strix aluco ) (Piault et al ., ) also showed that melanin‐based colouration is genetically correlated with numerous phenotypically plastic traits. Similar results are currently being accumulated in different taxa (birds: Kim et al ., ; fish: Wedekind et al ., ; Marie‐Orleach et al ., ; insects: Armitage & Siva‐Jothy, ), strengthening the claim that melanin‐based colouration covaries with phenotypically plastic traits such as immunity, body mass and hormone levels, even in cases in which the expression of this type of colour trait is not, or is only weakly, sensitive to body condition but is strongly genetically inherited. In other words, whether individuals are in good condition (healthy, well fed, whether they invest high or low effort in activities such as reproduction), they produce their genetically programmed colour trait.…”

Genetic basis and fitness correlates of dynamic carotenoid‐based ornamental coloration in male and female common kestrels Falco tinnunculus

“…Full details of the pedigree statistics can be found in Kim et al . (). The rate of extra‐pair paternity in our study population as well as in other kestrel populations is below 5% (J.A.…”