Gadau, Jurgen. “Transitions in Social Evolution.” (2009).
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TRANSITIONS FROM SOLITARY to social living and between alternative social phenotypes did not happen just once or in the distant past, as did the transition from prokaryotes to eukaryotes. Such transitions continue to be observed today in facultative eusocial halictine bees that switch between a solitary and social lifestyle and in ant species with colonies headed by a single or multiple queens depending on the population studied. The wide-spread occurrence of such transitions raises the question of whether these transitions are major or minor. Social insects have two important advantages for someone interested in studying the mechanistic basis of evo-lutionary transitions from solitary to social living, or from one social phenotype to another. First, because these transitions can be studied in extant species, detailed mechanistic analyses of the underlying genetic, physiological, or developmental changes responsible for these transitions are possible. Second, because there are many major and minor transitions that happen in phylogenetically independent groups, comparative studies en-able us to understand the selective forces shaping these transitions.