Evolutionary genetics of personality in the Trinidadian guppy I: Maternal and additive genetic effects across ontogeny (article)

Abstract

Among-individual variation in behaviour is a widespread phenomenon, with several frameworks developed to explain its existence. Maternal effects, which can have significant influence over evolutionary processes, are an under-studied source of behavioural variation. Maternal effects are not necessarily static however, since their importance can change over offspring ontogeny, typically declining with age relative to additive genetic effects. Here, using a quantitative genetics approach, we test the prediction that maternal effects will influence age33 specific risk-taking behaviour in Trinidadian guppies, Poecilia reticulata. Individuals were subject to a single open field trial as juveniles and up to 4 repeat trials as adults, with 5 traits indicative of risk-taking behaviour measured in each trial. We then partitioned phenotypic 36 variance into additive genetic (VA) and maternal identity (VM) components, in addition to 37 testing brood size and maternal weight as specific sources of maternal effects. We found that 38 VM had significant influence over juvenile traits, with very low VA estimates. Whereas, in 39 adults, all traits were significantly heritable, with little support for VM. We also found a strong 40 influence of maternal traits on juvenile behaviours as predicted, with significant, albeit smaller, effects found in adults. Maternal weight was heritable and itself subject to maternal effects. Thus, maternal weight is a likely source of maternal genetic effects that are expected to alter response to selection on personality in this system. More generally our study highlights that while maternal effects can be an important source of personality variation, this varies over ontogeny of offspring.