Editorial New insights from the figefig wasp model interaction system Keyword: Ficus The genesis of this special volume on fig biology was the VIII In- ternational Fig Symposium held in June 2012, in Ribeirão Preto, Brazil. The series of international fig symposia started with two mini-symposia, with the first in Paris in 1983, and the next in Mont- pellier in 1984. The subsequent fig symposium in Miami, in 1988, was the first to be followed by a special volume in an indexed jour- nal. Four founding fathers of fig biology and fig taxonomy were pre- sent at the first meeting: Kees Berg (1934e2012), Jacob Galil (1914e 1993), Koos Wiebes (1931e 1999) and Georges Valdeyron (1914e 2013). In the footsteps of these giants, studies on fig biology have blossomed throughout the world, leading to a diversified global vision of the maybe 800 species of Ficus. It is now possible to compare independently evolved interactions in different biogeo- graphical realms in order to detect repeated evolution of similar traits and hence to formulate general rules about such interactions. Fascinating insights have been provided by this system into evolu- tionary and ecological questions centred around mutualisms. Ficus (Moraceae) are characterized by their enclosed, urn- shaped inflorescence (the fig or syconium) and their highly special- ized pollinators (Hymenoptera, Chalcidoidea, Agaonidae). When receptive to pollen, the figs release an odor that attracts their spe- cific female pollinators. The wasps penetrate the fig through the fig opening or ostiole, pollinate female flowers, and lay eggs inside some of them, introducing their ovipositor through the styles. These pollinating females die shortly thereafter. Flowers that only receive pollen develop into seeds and those that receive an egg develop into galls. Both seeds and pollinator larvae develop once the short pollen-receptive phase is over. Once wasp offspring devel- opment is completed, mature males eclose from their galls and mate with mature females before their movement into the fig cav- ity. Male flowers are mature by this time which allows pollinator fe- males to acquire pollen either passively or actively. In the active process, females collect pollen from the anthers and store it in spe- cial thoracic pockets; such females will actively deposit pollen on styles during oviposition. In the passive process, females acquire pollen by brushing against anthers and pollen is passively depos- ited during oviposition. Male wasps cut an exit hole through the fig wall, allowing female wasps to escape the fig and to leave in search of a pollen-receptive fig. Male wasps are wingless and usu- ally only mate in their natal fig. Finally the fig ripens and seed dispersal is ensured by frugivorous animals such as birds, bats or other mammals, or by insects such as ants. This is the typical devel- opment of a monoecious fig in which male and female flowers occur in the same syconium. In dioecious figs, fig wasps develop within male trees that bear only short-styled staminate flowers, while seeds develop within female trees that bear only long- styled pistillate flowers. Dioecious figs are absent in the New World, providing another fascinating ecological and evolutionary puzzle. Heterogeneous style length is at the center of the fig e pollinating wasp interaction. In the early 1980s, fig biologists real- ized that ovipositor length of pollinators could not explain why seeds are mainly produced in long-styled flowers and wasps in short-styled flowers in monoecious figs: individual selection on the wasps should have selected for longer ovipositors allowing them to oviposit in all female flowers. Since then a number of com- plementary explanations have been proposed for why eggs are preferentially laid in the ovules of short-styled flowers that are located close to the fig cavity, far away from the outside of the fig (e.g. Herre et al., 2008). However, it is only now that we may have a simple histological explanation for the riddle of how pistil- late flowers growing side by side in monoecious figs can present contrasting style lengths. New histological data show that in monoecious figs the development of pistillate flowers is asynchro- nous (Basso-Alves et al., in this volume). Asynchronous develop- ment of pistillate flowers associated with dense flower packing could result in variable flower pedicel lengths and, as a conse- quence, in variable style lengths since the styles of all flowers reach the same height forming a surface within the fig cavity. Male flower morphogenesis is surprisingly heterogeneous among fig species. For instance in some fig species, staminate flowers start out with bisexual floral primordia, but in most species the female organs abort to result in staminate flowers (Basso-Alves et al., in this volume). Beyond pollinators, figs host communities of parasitic fig wasps. These wasps include gall inducers, kleptoparasites and parasitoids, developing within the fig and generally emerging from figs at the same time as the pollinators. Some of them are much larger than the pollinators, some are pollinator-sized. Only few such commu- nities are described with data on the actual diet of the different wasp species, and little is known about the cost of these parasites to the fig-pollinating wasp mutualism. In this volume, Segar et al. and Conchou et al. describe the wasp communities associated with two Ficus species. In Ficus guianensis, the presence of large par- asites results in a considerable decrease in the number of pollina- tors and seeds developing within the figs while in Ficus rubiginosa, many pollinator wasps die within figs without manag- ing to emerge from them when large parasites are present. In both situations, the development of large parasites induces dispro- portionate reduction in plant fitness. Most interestingly, Tzeng et al. (in this volume) demonstrate that in the dioecious Ficus erecta, male figs, within which pollinating wasps breed, have thicker walls Contents lists available at ScienceDirect Acta Oecologica journal homepage: www.elsevier.com/locate/actoec Acta Oecologica 57 (2014) 3e4 1146-609X/$ e see front matter Ó 2014 Elsevier Masson SAS. All rights reserved. http://dx.doi.org/10.1016/j.actao.2014.01.002