Indirect Genetic Effects for Survival in Domestic Chickens (Gallus gallus) Are Magnified in Crossbred Genotypes and Show a Parent-of-Origin Effect

Abstract

Through social interactions, individuals can affect one another's phenotype. The heritable effect of an individual on the phenotype of a conspecific is known as an indirect genetic effect (IGE). Although IGEs can have a substantial impact on heritable variation and response to selection, little is known about the genetic architecture of traits affected by IGEs. We studied IGEs for survival in domestic chickens (Gallus gallus), using data on two purebred lines and their reciprocal cross. Birds were kept in groups of four. Feather pecking and cannibalism caused mortality, as beaks were kept intact. Survival time was shorter in crossbreds than in purebreds, indicating outbreeding depression and the presence of nonadditive genetic effects. IGEs contributed the majority of heritable variation in crossbreds (87 and 72%) and around half of heritable variation in purebreds (65 and 44%). There was no evidence of dominance variance, neither direct nor indirect. Absence of dominance variance in combination with considerable outbreeding depression suggests that survival is affected by many loci. Direct-indirect genetic correlations were moderately to highly negative in crossbreds (20.37 6 0.17 and 20.83 6 0.10), but low and not significantly different from zero in purebreds (0.20 6 0.21 and 20.28 6 0.18). Consequently, unlike purebreds, crossbreds would fail to respond positively to mass selection. The direct genetic correlation between both crosses was high (0.95 6 0.23), whereas the indirect genetic correlation was moderate (0.41 6 0.26). Thus, for IGEs, it mattered which parental line provided the sire and which provided the dam. This indirect parent-of-origin effect appeared to be paternally transmitted and is probably Z chromosome linked.

The quantitative genetics of indirect genetic effects: a selective review of modelling issues

“…In A. thaliana, in contrast, Mutic and Wolf (2007) found positive pleiotropic direct and indirect effects on size-, development-and fitness-related traits. Results of Peeters et al (2012) in laying hens suggest that non-additive effects may have substantial impact on the direct-indirect genetic correlation. They found moderately to strongly negative direct-indirect genetic correlations in crossbred individuals, whereas the correlation was near zero in the purebred parental lines.…”

“…In cannibalistic laying hens, for example, the IGE of an individual on the survival probability of its group mates relates to its pecking behaviour. Nevertheless, the variance-component model allows quantifying IGEs solely from survival data and knowledge of which individuals interact with each other (that is., cage composition), without any information on pecking behaviour of individuals (Peeters et al, 2012). The trait-based model, by contrast, requires the inclusion of all traits that functionally underlie the IGE on the focal trait.…”

“…The ideal data, therefore, consists of many small groups of equal size, all kept in the same macro environment, such as, for example, a large laying house with hens kept in cages of a few individuals (for example, Peeters et al, 2012). Estimating IGEs becomes difficult when groups are large and few, or present in different environments.…”

“…Evidence is increasing that IGEs can make a meaningful contribution to heritable variation in populations (for example, Mutic and Wolf, 2007;Peeters et al, 2012). IGEs can, therefore, contribute to response to selection, at least in the short term.…”

Productive Performance in Local Chicken After Five Generations of Crossing and Selection for High Live Body Weight

“…Schmidt et al (2006) reported that selection for increased LBW in broiler breeders includes maternal effects which have positive association with the LBW of its progenies after hatch. In addition, Peeters et al (2012) stated that individuals can affect one another's phenotype. The heritable effect of an individual on the phenotype of a conspecific individual is known as an indirect genetic effect (IGE).…”