Heritability and genetic correlation between the sexes in a songbird sexual ornament

Abstract

The genetic correlation between the sexes in the expression of secondary sex traits in wild vertebrate populations has attracted very few previous empirical efforts of field researchers. In southern European populations of pied flycatchers, a sexually selected male ornament is also expressed by a proportion of females. Additive genetic variances in ornament size and expression, transmission mechanisms (autosomal vs Z-linkage) and maternal effects are examined by looking at patterns of familial resemblance across three generations. Size of the secondary sex trait has a genetic basis common to both sexes, with estimated heritability being 0.5 under an autosomal model of inheritance. Significant additive genetic variance in males was also confirmed through a crossfostering experiment. Heritability analyses were only partially consistent with previous molecular genetics evidence, as only two out of the three predictions supported Z-linkage and lack of significant mother-daughter resemblance could be due to small sample sizes caused by limited female trait expression. Therefore, the evidence was mixed as to the contribution of the Z chromosome and autosomal genes to trait size. The threshold heritability of trait expression in females was lower, around 0.3, supporting autosomal-based trait expression in females. Environmental (birth date) and parental effects on ornament size mediated by the mother's condition after accounting for maternal and paternal genetic influences are also highlighted. The genetic correlation between the sexes did not differ from one, indicating that selection on the character on either sex entails a correlated response in the opposite sex.

Carry‐over effects of conditions at the wintering grounds on breeding plumage signals in a migratory bird: roles of phenotypic plasticity and selection

“…The forehead patch size was highly repeatable, indicating high heritability or permanent environmental effects on this trait during the early development. This is in agreement with a previous study that found high heritability for forehead patch size in male pied flycatchers of the Iberian population (Potti & Canal, ). Moreover, the fact that we did not find any correlation between environmental conditions during the prebreeding moult and the size of the forehead patch supports the idea that the forehead patch size is more genetically than environmentally determined.…”

Hind Wing Shape Evolves Faster than Front Wing Shape in Calopteryx Damselflies

“…Kiauta 1969). Cases where traits that are under sexual selection in one sex also appear in the opposite sex may result from intralocus sexual conflict (Bonduriansky and Rowe 2005;Poissant et al 2009;Potti and Canal 2011). It should be emphasised, however, that there is a clear wing shape dimorphism between males and females (see also Johansson et al 2009).…”

Lifetime fitness and age‐related female ornament signalling: evidence for survival and fecundity selection in the pied flycatcher

“…In Iberian populations of pied flycatchers ( Ficedula hypoleuca Pallas, 1764), some females express a forehead patch of pale (white or creamy) feathers similar to that all males display, although often smaller (by a half, on average; Potti & Canal, ). Both genetic (Potti, ; Potti & Canal, ) and functional (Potti & Merino, ; Morales et al ., ) hypotheses have been invoked to explain female expression as well as size of the ‘male’ ornament in these populations.…”

“…In Iberian populations of pied flycatchers ( Ficedula hypoleuca Pallas, 1764), some females express a forehead patch of pale (white or creamy) feathers similar to that all males display, although often smaller (by a half, on average; Potti & Canal, ). Both genetic (Potti, ; Potti & Canal, ) and functional (Potti & Merino, ; Morales et al ., ) hypotheses have been invoked to explain female expression as well as size of the ‘male’ ornament in these populations. A preference of males for females displaying large forehead patches has been suggested on the basis of the reported assortative mating with respect to trait size (Potti & Merino, ; Potti & Canal, ) and the signalling of their age and parasite (trypanosome)‐free condition by ornamented females (Potti & Merino, ) although the possibility that assortative mating may be due to reasons other than mate choice cannot be discarded (Burley, ; Roulin, ; Kraaijeveld et al ., ).…”