Development of shy/bold behaviour in squid: context-specific phenotypes associated with developmental plasticity

Animals often differ from one another in their willingness to take risks in a number of functional contexts related to fitness (e.g. mating, dispersal, and foraging behaviour). Although several studies have reported life history correlates and selective consequences of this variation in shy/bold behaviour, little attention has been paid to developmental processes resulting in shy/bold phenotypes. Here, we present a lifetime developmental study of shy/bold behaviour in dumpling squid, Euprymna tasmanica. Behaviour was measured in two test contexts, a threat and a feeding test, at five times across the entire life span. Across test contexts, shy/bold behaviour was not correlated at any age; while within a test context, individual shy/bold phenotypes were consistent both before and after sexual maturity. During sexual maturity, different phenotypes displayed different amounts of developmental variation; shyer animals were more plastic in feeding tests, while bolder animals were more plastic in threat ones. Our results suggest that for some animals shy/bold behaviour throughout development is uncorrelated across different contexts related to risk, while within a context, there may still be developmental constraints to changing shy/bold behaviour. This constraint within a functional context, however, may be phenotype-specific, with some phenotypes able to change more than others. These results indicate that a greater understanding of developmental pathways is needed to determine whether shy/bold phenotypes per se are the sole focus of selection. Differences in developmental plasticity between shy/bold phenotypes may also confer differential fitness in fluctuating environments.