Parental predator exposure affects offspring boldness and laterality in the stickleback

Parental influences on offspring phenotype occurring through pathways
other than via inherited DNA sequences are known as parental effects.
Parental effects profoundly influence offspring behaviour, including
behaviour laterality and personality, two traits that are widespread and
of fundamental importance in the animal kingdom with clear fitness
consequences. However, the impact of parental effects on the interaction
between behavioural laterality and personality within the same species has
not been previously explored. If such a link exists, it would deepen our
understanding of personality traits, extending them to brain laterality
and its underlying neurobiology. In addition, if both traits are causally
linked, it may constrain evolution as changing one of these traits would
affect the other.  The aim of this study was to examine whether
offspring personality traits and behavioural laterality are related and
can simultaneously be influenced by parental effects, suggesting a common
underlying mechanism. Here we exposed parents of an egg laying species,
the stickleback (Gasterosteus aculeatus), to predator cue or not and
examined the impact of this exposure on the two behavioural traits of
their offspring. Shortly after laying, clutches were split: half were
reared without predator cues for 12 weeks before behavioural testing, and
the other half were used for cortisol analysis. We found that
both parents and offspring from predator-exposed parents were bolder, with
the offspring more likely to show lateralized behaviour, and were smaller
than offspring from parents that were not exposed to predation. The egg
cortisol levels were too low to be detected by LC/MS-MS. To our knowledge,
these results are the first to indicate that parental effects under
varying predation conditions can influence laterality, personality, and
growth of offspring within the same individuals, though further evaluation
and experiments are needed to determine the role of maternal cortisol.