Personality and its fitness consequences in the Seychelles warbler (Acrocephalus sechellensis)

In this thesis, I investigate whether differences in behaviour among individuals, termed personality, are genetically determined and/or shaped by state and whether personality influences reproductive success and strategy. Using the Cousin Island population of Seychelles warbler (Acrocephalus sechellensis), I measured five personality traits: exploration of a novel object, exploration of a novel environment, obstinacy, stress
response and escape response. I estimated the repeatability of each trait, the heritability of the repeatable traits and tested for correlations among repeatable traits. I found that exploration of a novel environment and object were repeatable and correlated, and novel environment exploration was heritable, suggesting that it may be under selection in the population. I then used a candidate gene approach to further investigate the genetic variation associated with personality, specifically targeting SERT and DRD4. I found no genetic variation in DRD4, but identified four polymorphisms in SERT that did not correlate with the novel environment or novel object exploration. These results suggest there was no association between these behaviours and variation in the candidate genes tested in this population, and that a genome-wide study might be beneficial to detect the relevant genes underlying personality. I then looked at how personality is potentially generated and maintained in a social living species by investigating whether personality is social state-dependent or reproductive state-dependent. I found that the novel environment and novel object exploration were not correlated with social status and behavioural consistency was unaffected by social status. Novel object exploration was instead associated with the interaction between insect abundance at year of birth and age (a proxy for reproductive state). Lastly, I investigated the fitness consequences of personality, particularly looking at its influence on reproductive behaviour. I found that disassortative pairs for novel environment exploration were more likely to have females engage in extra pair parentage, and that novel environment and novel object exploration were not associated with the number of offspring sired or the ratio of within to extra group young. Overall my results show that there are consistent among individual differences in behaviour in wild cooperative breeders that may be generated by future fitness potential and are associated with reproductive behaviour within the social pair.