Developmental plasticity and social specialization in cooperative societies

Cooperative breeding systems showcase the diversity of social trajectories within and among species, ranging from the extremes of eusocial insects where individuals become irreversibly specialized as fecund queens or sterile workers, to vertebrate systems where individuals maintain the flexibility to breed throughout life. Between these extremes lies a continuum with individuals exhibiting varying degrees of specialization in their behaviour. Most research on cooperative breeders, particularly on vertebrate systems, has focused on why helping has evolved, rather than addressing this diversity. Here, we present a framework to explain variation in the timing, extent and flexibility of phenotypic divergence across vertebrate and invertebrate cooperative systems. We base our framework on recent theory about how individuals integrate information about the environment from different sources (genes, parents and direct experiences) when establishing their developmental trajectory. We discuss how the timing and degree of divergence and specialization are influenced by the availability and reliability of information about later fitness options and by the extent to which individuals have control over their development. Throughout, we use this developmental perspective to draw broad comparisons across vertebrate and invertebrate systems, which are often considered separately.