The benefits of grouping as a main driver of social evolution in a halictine bee.

Over the past decade, the cause of sociality has been much debated. Inclusive fitness [ in Hamilton's rule ( - > 0)] has been criticized but is still useful in the organization of a framework by elucidating mechanisms through which (benefit × relatedness) becomes larger than (cost). The bee is suitable for investigation of this issue because of the sympatric occurrence of both social and solitary nesting in its populations.

Effects of aphid parasitism on host plant fitness in an aphid-host relationship.

Aphids are serious agricultural insect pests which exploit the phloem sap of host plants and thus transmit pathogens to their hosts. However, the degree to which aphid parsitism affects the fitness of the host plants is not well understood. The aphid, Macrosiphoniella yomogicola, parasitizes the mugwort Artemisia montana in Japan.

Adaptive phenotypic variation among clonal ant workers.

Phenotypic variations are observed in most organisms, but their significance is not always known. The phenotypic variations observed in social insects are exceptions. Genetically based response threshold variances have been identified among workers and are thought to play several important adaptive roles in social life, e.

Nature of collective decision-making by simple yes/no decision units.

The study of collective decision-making spans various fields such as brain and behavioural sciences, economics, management sciences, and artificial intelligence. Despite these interdisciplinary applications, little is known regarding how a group of simple 'yes/no' units, such as neurons in the brain, can select the best option among multiple options. One prerequisite for achieving such correct choices by the brain is correct evaluation of relative option quality, which enables a collective decision maker to efficiently choose the best option.