A Selfish Genetic Element Influencing Longevity Correlates with Reactive Behavioural Traits in Female House Mice (Mus domesticus)

According to theory in life-history and animal personality, individuals with high fitness expectations should be risk-averse, while individuals with low fitness expectations should be more bold. In female house mice, a selfish genetic element, the t haplotype, is associated with increased longevity under natural conditions, representing an appropriate case study to investigate this recent theory empirically. Following theory, females heterozygous for the t haplotype (+/t) are hypothesised to express more reactive personality traits and be more shy, less explorative and less active compared to the shorter-lived homozygous wildtype females (+/+). As males of different haplotype do not differ in survival, no similar pattern is expected. We tested these predictions by quantifying boldness, exploration, activity, and energetic intake in both +/t and +/+ mice. +/t females, unlike +/+ ones, expressed some reactive-like personality traits: +/t females were less active, less prone to form an exploratory routine and tended to ingest less food. Taken together these results suggest that differences in animal personality may contribute to the survival advantage observed in +/t females but fail to provide full empirical support for recent theory.