International Union for the Study of Social Insects International CongressInternational Congress 13 - 18 July 2014 | Cairns Convention Centre | Queensland, Australia ABSTRACTS www.iussi2014.com Oral Presentations OR001 Natural selection on the regulation of foraging in harvester ants Deborah M. Gordon A long-term study of a population of colonies of the desert seed-eating ant Pogonomyrmex barbatus has made it possible to investigate how natural selection is shaping collective behavior. It appears that colonies that regulate foraging so as to conserve water in current drought conditions are more likely to have offspring colonies. Behavioral studies show that colonies regulate foraging activity according to food availability and current humidity. The collective behavior that regulates foraging activity is based on positive feedback from interactions of outgoing and returning foragers. Demographic data and observations of foraging activity show no evidence of any behavioral or ecological differences between the two lineages of this dependent-lineage population. There is variation among all colonies in the regulation of foraging activity, and we are investigating how this variation arises from differences among colonies in how individual ants respond to interaction. Using microsatellite variation at 5 loci, we matched parent and offspring colonies, as colonies founded by daughter queens of a known parent queen, for 270 colonies of known age. We were able to estimate a life table for this population of colonies and to estimate the female component of colony lifetime reproductive success. Only about 25% of colonies have offspring colonies, and surprisingly, we found no evidence of reproductive senescence in the 20-30 lifespan of a colony. There is evidence of heritability from parent to offspring colonies in the regulation of foraging, and we are investigating this further. Since variation among colonies in the regulation of foraging behavior is associated with variation in colony lifetime reproductive success, it appears that natural selection is shaping collective behavior so as to favor less foraging activity in poor conditions. OR002 Individual personalities within a honeybee colony Alexander Walton, Amy Toth Individual differences, often referred to as personalities or behavioral syndromes, are an important new area of investigation in the biological and social sciences and are being investigated in many animals and humans. Differences in personalities are something we hold dear as humans because they not only make us who we are, but lead to role specialization, and thus contribute to the maintenance of a functioning society. It is likely that personality differences can serve a similar role in an insect society. I have hypothesized that some individuals in the hive have an ‘affiliative’ personality: that throughout their lifetime they perform tasks that require interacting with their nestmates. I have also hypothesized that there are ‘non-affiliative’ bees that perform non- interactive tasks throughout their life. Detailed observations on individual bees can be achieved with an observation hive, a glass-walled bee hive that allows for monitoring of activity within the colony without disturbing the insects. We built observation hives and recorded the behaviors of individually marked, same-age bees throughout their 5 week lifetime for four different hives. Tasks were placed into the categories of affiliative or non-affiliative based on the criteria of whether the task does or does not require interaction with another individual. Analyses are ongoing but results thus far suggest there are inter-individual differences in several social behaviors. Investigation of individual differences in personalities within the social insect colony could provide insight into the role of specialization during social evolution. Further research can illuminate how personalities may contribute to the fitness and success of the colony 2 OR003 Adult-larva epistasis affects development and fitness in a clonal ant Serafino Teseo, Nicolas Châline, Pierre Jaisson, Daniel J.C. Kronauer In social species, the phenotype and fitness an individual depend not only on its genotype, but also on the genotype of its social partners. However, how these indirect genetic effects affect genotype fitness in competitive situations is poorly understood, for example because of the lack of control over the genetic composition of social groups. In our study, we investigate how indirect genetic effects affect phenotypic plasticity and fitness of two clones (A and B) of the parthenogenetic ant Cerapachys biroi, both in monoclonal and chimeric colonies. We show that, while clone B has lower fitness in isolation, it consistently outcompetes clone A in chimeras. The reason is that, in chimeras, clone B produces more individuals specializing in reproduction rather than cooperative tasks, behaving like a facultative social parasite. A cross-fostering experiment shows that the proportion of larvae that develop in high-reproductive individuals depends on intergenomic epistasis between larvae and nursing adults, explaining the flexible allocation strategy of clone B. In C. biroi, larval fate depends thus not only on the genotype of the larvae, but also on the genotype of the nursing adults, which exert a control over larval development. This mechanism has possibly evolved to maintain an optimal colony-level allocation in reproductive vs. ergonomic tasks within monoclonal natural colonies, but its clone-specific calibration leads to differential fitness levels for different clones mixed within the same colony. Our study shows that intergenomic epistasis could be a possible proximate mechanism for social parasitism in ants, and reveals striking analogies between social insects and social microbes. OR004 Social synchronization of activity rhythms and the temporal organization of honeybees Taro Fuchikawa, Moshe Nagari, Ada Eban-Rothschild, Guy Bloch Temporal organization of activity may improve the coordination and efficiency of insect societies. Young honeybee workers typically perform in-hive activities such as brood care and therefore spend most of the time inside the dark and theromoregulated hive. Nevertheless, when removed from the hive they show circadian rhythms in locomotor activity and brain clock gene expression that are synchronized to the ambient day-night cycles. We examined the relative importance of social and light synchronization in free-foraging colonies by exposing young nest bees to conflicting social and photic environmental cycles. We established hives with conflicting information for photic (illumination regime) and social (forager activity) environmental cycles. To determine the phase relationships between the bee rhythms and these two conflicting environmental cycles we transferred bees from the hive to individual cages in constant lab conditions and monitored their locomotor activity. We found that: (1) the rhythms of foragers were synchronized to the hive entrance opening and closing cycle, (2) the rhythms of nurse-age bees that were housed in a cage adjacent to the observation hive were synchronized to the illumination regime, (3) the rhythms of nurses were similar to that of foragers in that the offset of activity was comparable to the time of hive entrance closing. In a complementary set of experiments we caged young bees in single- and double-mesh enclosures inside the hive. These experiments showed potent social synchronization even in bees deprived of direct contact with the brood or other bees. Together our results suggest that nest honeybees adjust their activity rhythms to environmental cycles through volatile, vibration, or microenvironmental cues related to forager activity. These findings are consistent with the hypothesis that the evolution of sociality in honeybees was associated with modifications in the circadian clock and its environmental regulation by social cues. 3 OR005 What is the relationship between altitude and ant colony size? Yi-Huei Chen, Elva Robinson Bergmann's rule describes an increase of body size from tropical to polar latitude; the rule also applies from low to high altitude. In terms of physiology and genetics, the colony is the unit of selection for ants; colony size (worker number in a colony) can be considered the body size of a colony. Combining these two ideas, this project uses two wood ant species, Formica lugubris and F. paralugubris, to investigate changes in colony size with altitude. We firstly developed an accurate and non-destructive method to estimate wood ant nest size (worker number) and also found that mound volume was feasible in representing nest size. We tested the hypothesis that nest size increases with increasing altitude in Swiss Jura Mountains during the summer 2012. Mound volume was used to estimate nest size and colony size. We found that canopy cover was probably a more important factor than altitude related to nest size variation. For a more comprehensive study with a wider altitudinal range, we investigated the relationship between altitude, canopy cover and polydomy of these two wood ant species along an altitudinal gradient (1200-2000 m) in the Swiss Alps in 2013. Overall, our results showed that colony size was larger both with rising altitude and with rising canopy cover. Temperature is the most likely underlying cause of these effects, due to the generally colder thermal environments both in shady areas and in higher altitude. Taken together, our findings demonstrate a positive trend