The diversity of social complexity in termites

Sociality underpins major evolutionary transitions and significantly
influences the structure and function of complex ecosystems. Social
insects, seen as the pinnacle of sociality, have traits like obligate
sterility that are considered ‘master traits’, used as single phenotypic
measures of this complexity. However, evidence is mounting that completely
aligning both phenotypic and evolutionary social complexity, and having
obligate sterility central to both, is erroneous. We hypothesise that
obligate and functional sterility are insufficient in explaining the
diversity of phenotypic social complexity in social insects. To test this,
we explore the relative importance of these sterility traits in an
understudied but diverse taxon: the termites. We compile the largest
termite social complexity dataset to date, using specimen and literature
data. We find that although functional and obligate sterility explain a
significant proportion of variance, neither trait are adequate singular
proxies for the phenotypic social complexity of termites. Further, we show
both traits have only a weak association with the other social complexity
traits within termites. These findings have ramifications for our general
comprehension of the frameworks of phenotypic and evolutionary social
complexity and their relationship with sterility.