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Free keywords:
animal model; breeding; candidate gene; circadian clock; heritability;
polymorphism; quantitative genetics; timing; wild population
Abstract:
Two commonly used techniques for estimating the effect of genes on traits in
wild populations are the candidate gene approach and quantitative genetic
analyses. However, whether these two approaches measure the same
underlying processes remains unresolved. Here, we use these two methods
to test whether they are alternative or complementary approaches to
understanding genetic variation in the timing of reproduction – a key trait
involved in adaptation to climate change – in wild tit populations. Our
analyses of the candidate gene Clock show weak correlates with timing
variables in blue tits, but no association in great tits, confirming earlier results.
Quantitative genetic analyses revealed very low levels of both direct (female)
and indirect (male) additive genetic variation in timing traits for both species,
in contrast to previous studies on these traits, and much lower than generally
assumed. Hence, neither method suggests strong genetic effects on the timing
of breeding in birds, and further work should seek to assess the generality of
these conclusions. We discuss how differences in the genetic control of traits,
species life-history and confounding environmental variables may determine
how useful integrating these two techniques is to understand the phenotypic
variation in wild populations.