David Zeh, associate professor of biology, was invited and delivered a plenary lecture at the 17th International Congress of Arachnology in Sao Pedro, Sao Paulo, Brazil, in early August.

The title of Zeh's plenary lecture was "The harlequin beetle riding pseudoscorpion: a hitchhiker's guide to evolutionary biology." The congress was attended by more than 320 arachnologists from 34 countries and all five continents. The scientific program was comprised of four and a half days of presentations, totaling five conferences, seven symposia and 115 oral presentations. A total of 259 posters were displayed.

An abstract of Zeh's lecture is presented below:

The neotropical pseudoscorpion, Cordylochernes scorpioides, has proven to be a model system for addressing fundamental questions in behavioral ecology and evolution. Distributed throughout the rain forests of Central and South America, C. scorpioides, inhabits decaying trees in the families Moraceae and Apocynaceae and disperses between these ephemeral and patchily-distributed habitats by hitchhiking under the wings of the giant harlequin beetle, Acrocinus longimanus. The beetle not only provides "jumbo jet" transport service for the pseudoscorpion but also serves as a strategic site for intercepting and inseminating females en route to colonizing newly-dead trees. Male C. scorpioides engage in intense, size-based competition to monopolize beetle abdomens as mobile mating territories. This pseudoscorpion is highly amenable to large-scale, behavioral, rearing and genetic studies of individuals derived directly from natural populations. As a polyandrous, viviparous invertebrate with indirect sperm transfer, C. scorpioides possesses a unique suite of reproductive and behavioral traits that makes it ideally suited for investigation of sexual selection, speciation and genomic conflict. These characteristics include: 1) rapid generation time and large brood size; 2) indirect sperm transfer via a spermatophore deposited on the substrate, and 3) live birth (viviparity) involving development of embryos in an external, translucent brood sac. External spermatophore deposition and diagnostic female behavior facilitate unambiguous assessment of female sexual receptivity and sperm transfer success, factors critical in studies of sperm competition, mechanisms of speciation and the adaptive significance of polyandry. In addition, C. scorpioides' "external-womb" form of viviparity greatly facilitates visual assessment of postzygotic reproductive incompatibility and the consequences of cellular endosymbiont (Wolbachia) infection.