A relatively small number of species on earth are highly social: they live in cooperative groups in which only some members reproduce, and others self-sacrificially assist the reproducing individuals by nurturing offspring, foraging, or defense and maintenance of the dwelling or nest. The ants, bees, and termites are familiar examples. In recent years, important discoveries have been made outside of these well-known groups. Now, the list of highly social organisms includes such diverse groups as African mole rats, aphids, thrips, snapping shrimp and even microorganisms. However, we still know very little about the breadth and diversity of group dynamics in most of these novel social species. Abbot's work focuses on social aphids, which produce highly aggressive larval soldiers that protect their mother from attack by predators. The purpose of the proposed study is to further develop our understanding of the dynamics of sociality in the soldier-producing aphids, building on promising results from prior work that revealed unexpected complexities in the societies of these social insects.
Abbot will employ highly variable molecular markers to explore cooperation and conflict in Pemphigus obesinymphae, the only North American social aphid studied in detail. In previous work, Abbot established that the social groups in which these aphids occur are invaded and exploited by intruders from neighboring groups. But prior work left unanswered fundamental questions about the patterns of conflict in aphid societies. This work uses microsatellite markers and field experiments to accurately quantify the pattern of relatedness in P. obesinymphae social groups, the relationship between relatedness and cheating in natural populations, and the consequences of cheating for colony productivity. Abbot's study will constitute the most thorough examination of cheating and conflict in social aphids to date. Results will advance our understanding of complexity in an important group of social organisms, and will offer social biologists new perspectives as they assemble the puzzle of exploitation and altruism across animals and microorganisms.
