Foitzik, Susanne Prof. Dr.
Dr. Susanne Foitzik
Academic and Research Appointments
Professor in Evolutionary Biology (W 3), Johannes Gutenberg University Mainz, 2010-
Professor in Behavioral Ecology (C 3), LMU Munich, 2004-2010
Wissenschaftliche Assistentin, (C1), University of Regensburg, 2000-2004
Postdoctoral Fellow, Colorado State University, Ft. Collins, USA, 1998-2000
Habilitation, Zoology, University of Regensburg 2004
Dr. rer. nat., Biology, Julius Maximilians University Würzburg 1998
Diploma, Biology, Julius Maximilians University Würzburg 1995
Grants and Scholarships
Honors and Awards
Speaker, EES Master Program, financed by the VW foundation, 2007-2010
DAAD Fellow, State University of New York, Albany USA, 1992-93
Academic and Research Appointments
DFG Fachkollegiatin "Biologie of bahavior and mind" 2011-
Member of the Senatsausschuss Evaluierung der Leibniz Gesellschaft 2011-
Member of the Faculty committee, LMU Munich, 2007-2010
Volkswagen-Foundation, Experten-Gespräche and Reviews 2009-
Academic and Professional Service Editorial Board of Insectes Sociaux 2006-
In the evolutionary biology group at the Institute of Zoology at the JoGu Mainz we are interested in the evolution, behavior and ecology of ants. We are using very diverse methods to explore our research questions including field manipulations, behavioral experiments, population and socio-genetics using neutral molecular markers such as microsatellites and DNA sequences, chemical analyses of the cuticular hydrocarbon and gland secretions, immunological and morphometric analyses and theoretical modeling and simulations. I will give an overview over recent, on-going and planned projects in my group.
Foto: Markus Rüger
The evolutionary significance of within- and between-colony variation in behavior, morphology, genetic composition and immuno-competence in ants
DFG Project Fo 298 / 11, PhD Student Andreas Modlmeier
Variation and heritability of traits connected to differential reproduction invariably leads to natural selection and hence to evolution. Yet, for many species the direction and strength of natural selection on specific traits is largely unknown. We will investigate which traits of Temnothorax ants are under selection in the field by estimating selection gradients on traits such as ant behavior (standardized tests of aggression, explorative, social behaviors), worker body size, heterozygosity, genetic diversity and immune-competence via trait-fitness regressions. In social insects, not only mean trait values can vary between independent evolutionary units – the colonies – but also variation in traits. Division of labor has been recognized as a primary cause for the ecological success of insect societies and we will test how behavioral, genetic, immunological and morphological variation among nest mates is associated with colony productivity. If a strong division of labor is adaptive, than ant colonies with stronger variation in behavior will be more productive. Preliminary studies demonstrate that colonies consistently vary in morphology and behavior and that within-colony behavioral variation is associated with a fitness correlate – per-capita-productivity. However, we could also show environmental influences on ant behavior, e.g. aggression of ant colonies increased with local nest density and social parasite contact. We therefore aim to identify how natural selection (acting on genes underlying behavior) and behavioral plasticity (a response to ecological conditions) influence ant behavior.
Internal conflicts, dispersal and the consequences of inbreeding in an ant with alternative reproductive tactics
PhD Student Ilka Kureck, Studienstiftung des deutschen Volkes
Social insects are models for the study of cooperation and conflicts in animal groups. Internal conflicts arise when selfish interests selected on the individual level counteract the interests of other group members. Their intensity and outcome are influenced by dispersal, sociogenetic structure and the fighting abilities of the competitors. The ant Hypoponera opacior exhibits a polyphenism with outbreeding winged sexuals and wingless reproductives that mate within or close to the maternal nest. Conflicts arise especially in-between and among wingless sexuals and between adult and developing colony members. Aim of this proposal is to uncover interrelations among genetic and social colony structure, the level of competition, individual reproductive success and internal conflicts. For example, we will investigate whether wingless mate-guarding males adjust their behavior to the competitive situation and the genetic structure of the nest. Wingless queens are subject to local resource competition and compete over the help of workers. We will study how dominance interactions, queen fertility and relatedness affect worker distribution. Frequent sibmatings of wingless sexuals lead to extremely high levels of inbreeding, and first analyses indicate fitness costs of inbreeding. We will analyze how dispersal and inbreeding affect internal conflicts and colony fitness using genetic and behavioral methods.
Selection and the evolution of resistance in structured host populations
DFG Project Fo 298 / 9, PhD Student Tobias Pamminger, Postdoc Dr. Pleuni Pennings
Raids of slavemaking ants, obligate social parasites that use allospecific workers to raise their young, cause severe fitness losses in their hosts. Consequently, hosts have developed defence strategies to avoid parasitation, but it was long thought that selection could not alter the behaviour of enslaved hosts. If slaves would stop working, slavemakers would only raid more to acquire additional slaves. Slaves were therefore thought to be caught in an evolutionary trap, where no behavioural strategy could increase their fitness and slave rebellion was predicted to be non-existent in ants. In contrast, we recently showed that Temnothorax slaves, instead of taking care of slavemaker (P. americanus) brood, kill many of the pupae. These killings result in smaller raiding parties, which less frequently attack host colonies. The destruction of parasite brood should increase the slaves’ indirect fitness if neighbouring host colonies are closely related. Hence the evolution of slave rebellion critically depends on host population structure. Here, we propose a thorough analysis of the costs and benefits associated with the killing behaviour. Population genetic analyses will determine relatedness between host nests in the slavemakers raiding range and we will study killing propensities in different populations. An analytical model will help to understand the relationship between population structure and the resistance trait “slave rebellion”.
The evolution of resistance and virulence in structured populations
Submitted grant proposal in collaboration with Dirk Metzler, LMU
Geographic patterns of resistance and virulence depend on the fitness consequences of these traits and the population structure. Socially parasitic slavemaking ants use allospecific workers - stolen during raids - to raise their young. Hosts developed defenses to evade parasitism - e.g. a newly found inducible defense - or to mitigate its costs after enslavement like the “slave rebellion” trait: enslaved Temnothorax workers were observed to kill pupae of the slavemaking ant Protomognathus americanus. The ensuing reduced growth of parasite nests leads to fewer and less destructive raids. We analyzed whether brood destruction raises the inclusive fitness of enslaved workers by reducing the raiding risk for related host colonies nearby. Genetic analyses detected weak host structure and host colonies that survived raids, which could directly benefit from rebellion of their slave relatives. A simulation showed that host structure and the costs of defense influence whether the slave rebellion trait can spread. Costs could include the erroneous killing of own brood and killing rates of parasite and host populations co-varied geographically. We now plan to explore how local structure and the costs / benefits of defenses explain the inter- and intra-population variation in trait expression for various defense traits. With theoretical models we will analyze how metapopulation structure affects the chances of defense or virulence allele to persist in a population. We will develop computational methods to estimate parameters of host-parasite interactions in in a metapopulation context.
The evolution of colony size in cavity-dwelling ants: the interplay between colony size and different life-history traits
Postdoc Dr. Inon Scharf, Minerva Foundation, PhD Student Boris Kramer, MPI Demographic research
Evolution leads to typical life-history traits in animals, such as age and size at first reproduction. In social animals, not only body size is under selection, but also group size. Larger colonies of social insects show increased survival, reproduction and competitive abilities. However, many social insect species are characterized by small colonies, so ecological or evolutionary factors must restrict colony growth. The benefits of large colony size are well understood. Less is known about the factors that limits colony size in small societies. We focus here on cavity-dwelling Myrmicine ants and study eight species from ten populations. This group of ants resides in woody material in the leaf litter of temperate forests, and they have small colonies with an average of 30-100 workers. We show that these ants are restricted to small colonies due to different factors. Worker production increases with colony size but levels-off quickly, pointing to an early end of the ergonomic phase. The common size distribution of these populations is right-skewed, with many small colonies and few large ones. This suggests a low colony survival and a high reproduction rate. In accordance with the “Michener’s paradox”, per-capita productivity sharply decreases with colony size. Polydomy, the usage of several nest sites by a single colony, can moderate this effect. In these solitarily foraging ants, polydomy should lower the costs of central-place foraging, by decreasing the travel time. Finally, colony size is linked to the social structure. Larger colonies are usually polygynous, having several reproducing queens. We uncover these general patterns in most ant populations and provide universal ecological explanations for why cavity-dwelling ants typically live in small colonies. The life-history trait colony size seems to depend on the foraging mode of these ants, their patterns of productivity, nest structure and social organization.
Individual and collective decision making and risk evaluation in slavemaking ants
DFG Project Fo 298 / 8, PhD Student Sebastian Pohl
Colonies of social insects are prime examples for cooperative decision making and collective intelligence. In contrast to the organisation of human societies where decisions are often made by one or few specially assigned individuals, decisions in ant societies are based on simple rules of thumb used by each ant. In the slave-making ant Protomognathus americanus, single scouts search for colonies of their Temnothorax hosts, which are subsequently attacked by a group of raiding workers. Scouts and raiders risk to get killed by host workers defending their colony. Considering both the raiding risk and the potential benefit, that is host pupae that could be raided and serve as slaves after eclosure, scouts must decide whether or not a discovered host colony is worth to be attacked. We investigated the occurrence of slave raids, host colony assessment and the final decision-making by P. americanus colonies during choice trials in the laboratory. We confronted slavemaker colonies with two host colonies of different demographic composition to analyse which host colony attributes are considered during the scouts’ decision process. Slavemaker colonies showed increased raiding activities when the slave : slavemaker ratio inside the slavemaker colony was low. Slavemakers did not favour host colonies with more pupae, but preferentially attacked colonies with more workers. These represent riskier raiding targets, but as larger colonies usually contain more brood in the field, the increased benefit may necessitate fewer raids, decreasing the total risk during a raiding season. However, confronted with two host colonies that showed more distinct benefit : risk ratios, their decision shifted. Thus raiding behaviour and decision-making in P. americanus are affected by a combination of external and internal stimuli.
Aggression in Temnothorax ants
Postdoc Dr. Inon Scharf, Minerva Foundation Cavity dwelling
Temnothorax ants live in small colonies of several dozens of workers in performed cavities in woody structures on the floor of temperate forests. Previous studies have shown that suitable nest places are an important limiting factor in these ecosystems. We use two model species, the American Temnothorax longispinosus and the European Temnothorax nylanderi to investigate aspects of the aggressive response of those ants to different potential intruders, differing in the level of danger they pose to the colony. The first project presented a detailed ethological analysis of the aggressive response of T. longispinosus to four species, including a slavemaking ant, Protomognathus americanus, which aims at stealing brood from the host colonies. The aggression was found to be gradual, based on the damage each invader can inflict on the host colony. T. nylanderi is used currently to check for consistency in aggressive behavior across colonies, and to understand the large variation in aggression we observe. Aggression depends of course on the opponent, but may also vary according to colony size, social structure and brood size. In addition, aggression can be correlated with the general activity level of the colony. Characterization of a group of traits which are correlated or of trade-offs among several traits is of great importance for understanding variation in behavior and how natural selection works. It can also help understanding why under some contexts “sub-optimal” behavior can be observed.
Recently started or planned projects: colleagues or students interested to be involved in these projects, please contact me.
Divergent sexual selection and sperm competition in Hypoponera ants
Sexual selection is intense on sexes with strong variation in reproductive success. In most species, these are the males and intrasexual selection resulted in weaponry and fighting abilities, while intersexual selection i.e. female choice has led to the evolution of elaborate ornaments or courtship behaviours. In situations, where females cannot select their mating partners or males have little means to interfere with their rivals, sexual selection can be mainly post-copulatory. During cryptic female choice is females can eject sperm of not preferred males and in species with multiple inseminations sperm competition chemical weapons in seminal fluids or competitive sperm morphology. In the ant Hypoponera opacior divergent sexual selection led to the evolution of two different male morphs. Winged males mate during nuptial flights and have little means to monopolize females. Wingless males copulate in the security of their own nest, guard mating partners, young queens, which are still enclosed in the cocoons, for several hours. In this situation, females cannot select their mating partner, but are frequently inseminated by several males. We will study sperm competition and cryptic female choice in the two sexual morphs of Hypoponera opacior and predict that the within-nest mating wingless sexuals should exhibit more traits selected through postcopulatory sexual selection than winged males which mate during nuptial flights.
Life history trade-offs in ant workers: the relationships between fertility, longevity, immunity and behavioural specialisation
In social insects important life history trade-offs are reversed. For example, fecund queens live much longer than sterile workers. Here, we plan to study life-history trade-offs among monomorphic workers of an ant species. We question, whether among these related, morphological similar worker individuals, reproductive investment and behavioural specialisation are associated with changes in life span and investment in immune defence. We will use a differential gene expression approach to reveal genes associated with behavioural specialization, fecundity and immuno-competence in ant workers and queens.
Ecological and genetic divergence of two hybridizing sister species of ants
The relative importance of ecological divergence and neutral genetic drift in speciation is still strongly debated in evolutionary biology. Geographically isolated populations can experience similar selection pressures or divergent habitat conditions can cause natural selection to act differently on fitness related traits. When ranges of sister species secondarily overlap, their ecological divergence could cause the occupation of sufficiently different ecological niches. Alternatively, if their ecological requirements have remained similar, strong interspecific competition might allow one species to out-compete the other, so that the ranges of the species do not overlap. In this project we investigate the role of ecological versus neutral genetic variation in speciation of two sister species of ants. We will study zones of secondary contact of these hybridizing sibling species, which arose in allopatry. We will evaluate ecological divergence by analyzing how natural selection acts on sympatric populations of the two species. In addition, we will use population genetics to quantify genetic divergence and introgression at neutral loci. Finally, if we detect neutral loci fixed for different alleles in the two species, we will investigate intra- and interspecific patterns of genetic variation in linked gene sequences. Low genetic variation (selective sweeps) would indicate positive directional selection.
Inducible defenses as part of social immunity
This project investigates whether social parasite contact induces adaptive changes in behaviour and allocation strategies of host ant colonies. Raids of slavemaking ants, obligate social parasites that use allospecific workers to raise their young, cause severe fitness losses in their hosts and as a result host species develop defences to circumvent parasitism. Studies on predator-prey systems showed, that if defenses are costly and predator occurrence is variable and unpredictable, prey defenses are selected to be inducible. Parasite presence causes changes in size, social organization and investment strategies of unparasitized Temnothorax host colonies and we will study whether these differences represent adaptive host responses. Host aggression increases during the summer raiding season and after parasite contact and we will investigate whether these and other behavioural responses can be considered inducible host defenses.
Genetic basis for antagonistic coevolution in social parasite systems
In this project we will study differential gene expression in social parasites and their hosts to identify genes involved in these host-parasite interactions. Invasion by parasites of an insect society should result in adaptive responses through changes in gene expression. This will be the first study to use representational difference analysis of cDNAs to contrast gene expression in host workers, which vary in their temporal-exposure to social parasites. In many host communities, social parasites enslave several host species and we will contrast expression patterns in parasite workers, which enslave different hosts. This will enable the analysis of genes underlying specialization to a single host, which have been indicated by chemical analysis of cuticular hydrocarbon profiles.
Publications in peer-reviewed journals
Foto: Birgit Fischer-Blass
2013 / In Press
Pohl, S., Foitzik, S. Parasite scouting and host defence behaviours are influenced by colony size in the slave-making ant Protomognathus americanus. Insectes Sociaux, in press.
Modlmeier, A.P., Foitzik S., Scharf, I. Starvation endurance of Temnothorax ants depends on group size, body size and access to larvae. Physiological Entomology, in press.
Kureck, I., Nicolai, B., Foitzik, S. Similar performance of diploid and haploid males in an ant species without inbreeding avoidance. Ethology, in press
Pamminger, T., Leingärtner A., Achenbach A., Kleeberg I., Pennings P.S., Foitzik S. 2013. Geographic distribution of the anti-parasite trait “slave rebellion. Evolutionary Ecology, 27: 39-49.
Kureck, I. M., Jongepier E. Nicolai, B., Foitzik, S. 2012 No inbreeding depression but increased sexual investment in highly inbred ant colonies. Molecular Ecology 22:5613-5623.
Scharf, I, Modlmeier, A.P., Beros, S., Foitzik S. 2012 Ant societies buffer individual-level effects of parasite infections. American Naturalist, 180: 671-683.
Modlmeier, A.P., Pamminger, T, Foitzik S., Scharf, S. Cold resistance depends on acclimation and behavioral caste in a temperate ant. Naturwissenschaften, 10: 811-819.
Pamminger, T, Modlmeier, A.P., Suette S., Foitzik S. Raiders from the sky: slavemaker founding queens select for aggressive host colonies. Biology Letters, 8: 748-750.
Steinmeyer, C, Pennings, P.S., Foitzik, S. Multicolonial population structure and nestmate recognition in an extremely dense population of the European ant Lasius flavus. Insectes Sociaux, 59: 499-510.
Pamminger, T., Leingärtner A., Achenbach A., Kleeberg I., Pennings P.S., Foitzik S. Geographic distribution of the anti-parasite trait “slave rebellion. Evolutionary Ecology, online first: DOI 10.1007/s10682-012-9584-07.
Konrad, M., Pamminger, T, Foitzik S. 2012. Two pathways ensuring social harmony. Naturwissenschaften, 99:627–636.8.
Modlmeier, A.P., Liebmann, J.A., Foitzik S. 2012. Diverse societies are more productive: a lesson from ants. Proceedings of the Royal Society B 279: 2142-2150.9.
Scharf, I, Modlmeier, A., Fries, S, Tirard C, Foitzik S. 2012. Characterizing the collective personality of ant societies: Aggressive colonies do not abandon their home. Plos One 7: e33314. 10.
Scharf, I, Ovadia, O., Foitzik S. 2012. The advantage of alternative tactics of prey and predators depends on the spatial pattern of prey and social interactions among predators. Population Ecology 54: 187-196.
Foitzik, S., Rüger, M., Kureck, I. Metzler, D. Macro- and microgeographic genetic structure in an ant species with alternative reproductive tactics in sexuals. Journal of Evolutionary Biology 24: 2721-2730.
Pohl, S., Witte, V., Foitzik, S. 2011. Division of labor and slave raid initiation in slave-making ants. Behavioral Ecology and Sociobiology, 65: 2029-2036.
Modlmeier, A. P., Foitzik, S. 2011. Productivity increases with variation in aggression among group members in Temnothorax ants. Behavioral Ecology. 22: 1026-1032 .
Scharf, I., Pamminger, T., Foitzik, S. Differential response of ant colonies to intruders: attack strategies correlate with potential threat. Ethology, 117: 731-739.
Kureck, I. M., Neumann A. and S. Foitzik 2011. Wingless ant males adjust mate-guarding behaviour to the competitive situation in the nest. Animal Behaviour, 82: 339-346.
Scharf, I., Bauer, S., Fischer-Blass, B, Foitzik, S. Impact of a social parasite on ant host populations depends on host species, habitat and year. Biological Journal of the Linnean Society, 103: 559-570.
Pamminger, T., Scharf, I., Pennings, P., Foitzik, S. 2011. Increased host aggression as an induced defence against slavemaking ants. Behavioural Ecology, 22: 255-260.
Scharf, I., Fischer-Blass, B, Foitzik, S. Spatial structure and nest demography reveal the influence of competition, parasitism and habitat quality on slavemaking ants and their hosts. BMC Ecology 2011, 11:9.
Abbot, P., Abe, D., ... Foitzik, S., ... Zink, A. 2011. Inclusive fitness theory and eusociality. Nature 471: E1-E4.
Foitzik, S., Fröba, J. Rüger, M.H., Witte, V. 2011. Competition over workers: Fertility signalling in wingless queens of Hypoponera opacior. Insectes Sociaux, 58: 271-287.
Pennings, P., Achenbach, A., Foitzik, S. 2011. Similar evolutionary potentials in an obligate ant parasite and its two host species. Journal of Evolutionary Biology, 24: 871-886.
Pohl, S., Foitzik, S. 2011 Slave-making ants prefer larger, better defended host colonies. Animal Behaviour, 81: 61-68.
Foitzik, S, Kureck, I., Rüger, M., Metzler, D. 2010. Alternative reproductive tactics and the influence of local competition on sex allocation in the ant Hypoponera opacior. Behavioral Ecology and Sociobiology, 64:1641–1654.
Achenbach, A., Witte, V., Foitzik, S. 2010 Brood exchange experiments and chemical analyses shed light on slave rebellion in ants. Behavioral Ecology, 21: 948 - 956.
Bauer, S., Böhm, M., Witte V., Foitzik, S. 2010. An ant social parasite in-between two chemical disparate host species. Evolutionary Ecology, 24: 317–332.
Foitzik, S, Bauer, S, Laurent, S., Pennings, P.S. 2009. Genetic diversity, populations structure and sex-biased dispersal in three co-evolving species. Journal of Evolutionary Biology, 22: 2470-2480.
Bauer, S., Böhm, M., Witte V., Foitzik, S. 2009. Fight or flight? A geographic mosaic in host reaction and potency of a chemical weapon in the social parasite Harpagoxenus sublaevis. Behavioral Ecology and Sociobiology, 64:45–56.
Foitzik, S., Achenbach, A., Brandt, M. 2009. Locally-adapted social parasite affects density, social structure and life history of its ant hosts. Ecology 90: 1195–1206.
Achenbach, A., Foitzik, S. 2009. First evidence for slave rebellion: Enslaved ant workers systematically kill the brood of their social parasite Protomognathus americanus. Evolution 63: 1068–1075.
Witte, V., Foitzik S., Hashim, R., Maschwitz, U., Schulz S. 2009. Fine Tuning of Social Integration in two Myrmecophiles of the Ponerine Army Ant, Leptogenys distinguenda. Journal of Chemical Ecology 35:355–367.
Heinze, J., Foitzik, S. 2009. The evolution of queen numbers in ants: from one to many and back. In Organization of Insect Societies: Edited by Jürgen Gadau and Jennifer Fewell; Harvard University Press, Cambridge, MA, USA, 26-50.
Witte, V., Leingärtner A., Sabaß L., Hashim R., Foitzik S. 2008. Symbiont microcosm in an ant society and the diversity of interspecific interactions. Animal Behaviour, 76: 1477-1486.
Feldhaar, H., Foitzik, S., Heinze, J. 2008. Life-long commitment to the wrong partner: hybridization in ants. Philosophical Transactions of the Royal Society B, 363: 2891-2899.
Rueger, M. H., Fröba, J., Foitzik, S. 2008. Larval cannibalism and worker-induced separation of larvae in Hypoponera ants: a case of conflict over caste determination? Insectes Sociaux, 55: 12-21.
Foitzik, S., Sturm, H., Pusch, K., D’Ettorre, P., Heinze, J. 2007. Variation in nestmate recognition abilities, chemical cues and genetic diversity in Temnothorax ants. Animal Behaviour, 73, 999-1007.
Beibl. J., Buschinger, A., Foitzik, S., Heinze. J. 2007. Phylogeny and phylogeography of the Mediterranean species of the parasitic ant genus Chalepoxenus and its Temnothorax hosts. Insectes Sociaux, 54, 189 – 199.
Brandt, M., Fischer-Blass, B., Heinze, J., Foitzik, S. 2007. Population structure and coevolution in social parasites. Molecular Ecology, 16, 2063–2078.
Pusch, K., Heinze, J., Foitzik, S. 2006. The influence of hybridization on colony structure in the ant species pair Temnothorax nylanderi and T. crassispinus. Insectes Sociaux, 53: 439 – 445.
Brandt, M., Heinze, J., Foitzik, S. 2006. Dufour's gland secretion as a propaganda substance in the slavemaking ant Protomognathus americanus. Insectes Sociaux, 53: 291–299.
Pusch, K., Seifert, B., Foitzik, S., Heinze, J. 2006. Distribution and genetic divergence of two parapatric sibling ant species in Central Europe. Biological Journal of the Linnaean Society 8: 223–234.
Fischer-Blass, B., Heinze, J., Foitzik, S. 2006. Microsatellite analysis reveals strong, but differential impact of a social parasite on its two host species. Molecular Ecology, 15: 638-872.
Beibl J., Stuart, RJ, Heinze, J., Foitzik, S. 2005. Six origins of slavery in formicoxenine ants. Insectes Sociaux, 52: 291–297.
Brandt, M., Heinze, J., Schmitt, T., Foitzik, S. 2005. A chemical level in the coevolutionary arms race between an ant social parasite and its hosts. Journal of Evolutionary Biology, 18: 576–586.
Brandt, M., Foitzik, S., Fischer-Blass, B., Heinze, J. 2005. The coevolutionary dynamics of obligate ant social parasites: Between prudence and antagonism. Biological Reviews, 80: 1–17.
Rüger, MH, Heinze, J., Foitzik, S. 2005. Polymorphic microsatellite loci in the ponerine ant Hypoponera opacior (Hymenoptera, Formicidae). Molecular Ecology Notes 5: 236–238.
Brandt, M., Foitzik, S. 2004. Community context and specialization influence coevolution in a slavemaking ant and its hosts. Ecology, 85: 2997–3009.
Fischer, B. Foitzik, S. 2004 Local co-adaptation leading to a geographic mosaic of coevolution in a social parasite system. Journal of Evolutionary Biology, 17: 1026-1034.
Foitzik, S., Backus, V. L., Trindl, A., Herbers, J. M. 2004. Ecology of Leptothorax ants: impact of food, nest sites and social parasites. Behavioral Ecology and Sociobiology, 55: 484-455.
Foitzik, S., Strätz, M. Heinze, J. 2003. Ecology, life history, and resource allocation in the ant, Leptothorax nylanderi. Journal of Evolutionary Biology, 16: 670-680.
Foitzik, S., Fischer, B., Heinze, J. 2003. Arms-races between social parasites and their hosts: Geographic patterns of manipulation and resistance. Behavioral Ecology, 14: 80-88.
Heinze, J., Foitzik, S., Fischer, B., Wanke, T. Kipyatkov, V. E. 2003. The significance of latitudinal variation in body size in a holarctic ant, Leptothorax acervorum. Ecography, 26: 349-355.
Foitzik, S., Heinze, J., Oberstadt, B., Herbers, J. M. 2002. Mate guarding and alternative reproductive tactics in the ant Hypoponera opacior. Animal Behaviour 63: 597-604.
Herbers, J. M., Foitzik, S. 2002. Ecology of slavemaking ants and their hosts in north-temperate forests. Ecology 83(1): 148-163.
Strätz, M., Foitzik, S., Heinze, J. 2002. First description of Leptothorax crassispinus from Bavaria. Nachrichtenblatt bayerischer Entomologen, 51: 26-29.
Foitzik, S., DeHeer, C. J., Hunjan, D. N., Herbers, J. M. 2001. Coevolution in host-parasite systems: Behavioral strategies of slavemaking ants and their hosts. Proceedings of the Royal Society B, London 268: 1139 – 1146.
Foitzik, S., Herbers, J. M. 2001. Colony structure of a slavemaking ant: I. Intra-colony relatedness, worker reproduction and polydomy. Evolution 55: 307-315.
Foitzik, S., Herbers, J. M. 2001. Colony structure of a slavemaking ant: II. Frequency of slave raids and impact on the host population. Evolution 55: 316-323.
Foitzik, S., Heinze, J. 2001. Microgeographic genetic structure and intraspecific parasitism in the ant Leptothorax nylanderi. Ecological Entomology 26: 449-456.
Herbers, J. M., DeHeer, C. J., Foitzik, S. 2001 Conflict over sex allocation drives conflict over reproductive allocation in perennial social insect colonies. American Naturalist 158: 178-192.
Foitzik, S., Heinze, J. 2000. Intraspecific parasitism and split sex ratios in a monogynous and monandrous ant. Behavioural Ecology and Sociobiology 47: 424-431.
Foitzik, S., Heinze, J. 1999. Non-random size differences between sympatric Leptothorax ants. Entomologia Generalis 24: 65-74.
Heinze, J., Foitzik, S., Oberstadt, B., Rüppell, O., Hölldobler, B. 1999. A female caste specialized for the production of unfertilized eggs in the ant Crematogaster smithi. Naturwissenschaften 86: 93-95.
Foitzik, S., Heinze, J. 1998. Nest site limitation and colony take-over in the ant Leptothorax nylanderi. Behavioral Ecology 9: 367-375.
Heinze, J., Rüppell, O., Foitzik, S., Buschinger, A. 1998. First records of ants (Hymenoptera: Formicidae) with cysticercoids of tapeworms (Cestoda: Dilepididae) from the Southwestern United States. Florida Entomologist 81: 122-125.
Heinze, J., Foitzik, S., Kipyatkov, V.E., Lopatina, E.B. 1998. Latitudinal variation in cold hardiness and body size in the boreal ant Leptothorax acervorum. Entomologia Generalis, 22: 305-312.
Foitzik, S., Haberl, M., Gadau, J., Heinze, J. 1997. Mating frequency of Leptothorax nylanderi ant queens determined by microsatellite analysis. Insectes Sociaux 44: 219-227.
Heinze, J., Foitzik, S., Hippert, A., Hölldobler, B. 1996. Apparent dear-enemy phenomenon and environmental-based recognition cues in the ant Leptothorax nylanderi. Ethology 102: 510-522.