Rose Trappes

Behavioural Ecological Individuality and Major Evolutionary Transitions in Individuality

Work on major evolutionary transitions in individuality is focused on the emergence of new evolutionary individuals: entities whose parts sacrifice independent reproduction and unite to form a unit of selection. Yet there are many different concepts of biological individuality: not just evolutionary individuality, but also immunological individuality, ecological individuality, and so on. How do different concepts of individuality relate to major transitions? In this talk I consider this question by focusing on the concept of behavioural ecological individuality. This concept is at work in organismal biology research on individual differences, such as animal personality and individual ecological specialisation. Behavioural ecological individuality refers first and foremost to phenotypic and ecological uniqueness, such that each individual has a unique set of phenotypic traits and ecological relations. The concept is in turn operationalised by studying individual differences, which contribute to uniqueness.

How does behavioural ecological individuality relate to major transitions in individuality? On the one hand, we can consider how new units of behavioural ecological individuality emerge, for instance new agents that exhibit coordinated behaviour irrespective of their reproductive capacity. On the other, we can ask whether behavioural ecological individuality plays a role in transitions in evolutionary individuality. Individual differences in behaviour and ecology, such as individual specialisation on foraging, defence and brood care in ant colonies, may be involved in transitions towards eusociality. Individual differences in the way organisms shape their niches might also affect the ability of individuals to come together to form a new reproductive unit. As well as contributing to discussions of major transitions, considering these connections can also help to integrate the currently somewhat fragmented debate on biological individuality.