Leptothorax Acervorum Research Articles

Ants of Kamchatka: checklist, DNA-barcoding and key (Hymenoptera, Formicidae)

Kamchatka is a remote volcanic peninsula in the sub-arctic Far East of Russia. Its myrmecofauna has been scientifically addressed several times. However, previous species lists are contradictory in part and a modern study seems to be lacking. Based on literature review, I conclude that 12 species and 4 genera (Camponotus, Formica, Leptothorax and Myrmica) of ants may be native to Kamchatka. Of those, 9 were found in the field, 3 having a Holarctic, 3 a trans-Palearctic and 3 an East Palearctic distribution. Most species diversity was found at mid-elevations, in pine shrubs and mixed forests, while deciduous forests and open habitats at lower altitudes were surprisingly species poor. DNA-barcoding was performed for 57 specimens/9 species. Genetic diversity (COI) was low for 8/9 species, with the exception of Leptothorax acervorum, for which all samples were of a different haplotype and 2 haplogroups were identified. For the encountered Holarctic and trans-Palearctic species, closely related haplotypes (<0.7% raw distance) occur in Europe and/or North America. Some Formica ants were morphologically atypical, with workers partially resembling those of F. fusca, while gynes identified as F. lemani. Morphometric analysis and DNA-barcoding suggested that all these specimens belong to a single species, F. lemani. Standard images for all specimens and an illustrated key to the worker caste are provided.

Brain and antennal transcriptomes of host ants reveal potential links between behaviour and the functioning of socially parasitic colonies.

Insect social parasites are characterized by exploiting the hosts' social behaviour. Why exactly hosts direct their caring behaviour towards these parasites and their offspring remains largely unstudied. One hypothesis is that hosts do not perceive their social environment as altered and accept the parasitic colony as their own. We used the ant Leptothorax acervorum, host of the dulotic, obligate social parasite Harpagoxenus sublaevis, to shed light on molecular mechanisms underlying behavioural exploitation by contrasting tissue-specific transcriptomes in young host workers. Host pupae were experimentally (re-)introduced into fragments of their original, another conspecific, heterospecific or parasitic colony. Brain and antennal mRNA was extracted and sequenced from adult ants after they had lived in the experimental colony for at least 50 days after eclosion. The resulting transcriptomes of L. acervorum revealed that ants were indeed affected by their social environment. Host brain transcriptomes were altered by the presence of social parasites, suggesting that the parasitic environment influences brain activity, which may be linked to behavioural changes. Transcriptional activity in the antennae changed most with the presence of unrelated individuals, regardless of whether they were conspecifics or parasites. This suggests early priming of odour perception, which was further supported by sensory perception of odour as an enriched function of differentially expressed genes. Furthermore, gene expression in the antennae, but not in the brain corresponded to ant worker behaviour before sampling. Our study demonstrated that the exploitation of social behaviours by brood parasites correlates with transcriptomic alterations in the central and peripheral nervous systems.

Reproductive Biology of Asarum sieboldii Miq.

The seasonal developmental rhythm, floral and fruit morphology, anthesis, and fructification of Asarum sieboldii were studied in a natural plant community in the southern part of the Russian Far East. The flower structure was investigated in ditails. It was found that the flower does not have a gynostemium. The flowers are protogynous. At the first anthesis stage, the anthers are closed and cross-pollination may be realized by ants (Hymenoptera) or flies (Dolichopodidae, Diptera). At the second stage of anthesis, there is direct contact of anthers with the pistil stigma and self-pollination occurs. The perianth is involved in the formation of fruit. The fruit is a six-locular, fleshy, half-inferior capsule. Asarum sieboldii has a high productivity of fruits and seeds. The fruit set is 89% after self-pollination. Viable seeds per fruit is 29 ± 2, the seed set is 69 ± 5%. The agents of seed dissemination are ants: Leptothorax acervorum and Myrmica ruginodis (Formicidae, Hymenoptera).

Body size but not colony size increases with altitude in the holarctic ant, Leptothorax acervorum

1. Bergmann's rule states that organisms inhabiting colder environments show an increase in body size or mass in comparison to their conspecifics living in warmer climates. Although originally proposed for homoeothermic vertebrates, this rule was later extended to ectotherms. In social insects, only a few studies have tested this rule and the results were ambiguous. Here, ‘body size’ can be considered at two different levels (the size of the individual workers or the size of the colony).2. In this study, data from 53 nests collected along altitudinal gradients in the Alps were used to test the hypotheses that the worker body size and colony size of the ant Leptothorax acervorum increase with increasing altitude and therefore follow Bergmann's rule.3. The results show that the body size of workers but not the colony size increases with altitude. Whether this pattern is driven by starvation resistance or other mechanisms remains to be investigated.

Phylogeography of social polymorphism in a boreo-montane ant.

BackgroundThe disjunct distribution of several Palearctic species has been widely shaped by the changes in climatic conditions during the Quaternary. The observed genetic differentiation or reproductive isolation between extant populations may be the outcome of their contemporary geographic separation or reproductive incompatibility due to differences in phenotypic traits which have evolved in isolated refugia. In the boreal ant Leptothorax acervorum, colonies from central and peripheral populations differ in social structure: colonies from Central and Northern Europe may contain several equally reproductive queens (facultative polygyny), while in colonies from peripheral populations in Spain only one the most dominant of several queens lays eggs (functional monogyny). By reconstructing the specie’s evolutionary and demographic history in Southwestern Europe we examine whether variation in social organization is associated with restricted gene flow between the two social forms.ResultsWe show that multi-queen colonies from all so far known inner Iberian populations of L. acervorum are functionally monogynous, whereas multi-queen colonies from all Pyrenean populations are polygynous, like those from other previously studied areas in Europe. Our analyses revealed complex spatial-genetic structure, but no association between spatial-genetic structure and social organization in SW-Europe. The population in the western Pyrenees diverged most strongly from other Iberian populations. Moreover, microsatellite data suggest the occurrence of recent bottlenecks in Pyrenean and inner Iberian populations.ConclusionsOur study shows a lack of reproductive isolation between the two social forms in SW-Europe. This in turn suggests that demographic and spatial patterns in genetic variation as well as the distribution of social phenotypes are better explained by co-variation with climatic, ecological, and historical factors. Moreover, we for the first time show the existence of substantial spatial-genetic structure in L. acervorum, suggesting the existence of multiple refugia in SW-Europe, including two extra-Mediterranean refugia in France. While gene flow among inner Iberian refugia may have been larger during the late glacial, extra-Mediterranean refugia in southern France may have contributed to the post-glacial recolonization of W-Europe.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0711-3) contains supplementary material, which is available to authorized users.

On evil and computational creativity

ABSTRACTThis paper touches upon the philosophical concept of evil in the context of creativity in general, and computational creativity in particular. In this work, dark creativity is introduced and linked to two important pre-requisites of creativity (i.e. freedom and constraints). A hybrid computational system is then presented; it includes one swarm intelligence algorithm, Stochastic Diffusion Search – mimicking the foraging behaviour of one species of ant, Leptothorax acervorum – and one physiological mechanism – imitating the behaviour of human immunodeficiency virus. The aim is to outline an integration strategy deploying the search capabilities of the swarm intelligence algorithm and the destructive power of the digital virus. The swarm intelligence algorithm determines the colour attribute of the dynamic areas of interest within the input image, and the digital virus modifies the state of the input image, creating the projection of “evil” over time (evil is used here as excessive use of underlying freedom). The paper concludes by exploring the significance of sensorimotor couplings and the impact of intentionality and genuine understanding of computational systems in the light of the philosophical concept of weak and strong computational creativity.

Queen-worker ratio affects reproductive skew in a socially polymorphic ant.

The partitioning of reproduction among individuals in communally breeding animals varies greatly among species, from the monopolization of reproduction (high reproductive skew) to similar contribution to the offspring in others (low skew). Reproductive skew models explain how relatedness or ecological constraints affect the magnitude of reproductive skew. They typically assume that individuals are capable of flexibly reacting to social and environmental changes. Most models predict a decrease of skew when benefits of staying in the group are reduced. In the ant Leptothorax acervorum, queens in colonies from marginal habitats form dominance hierarchies and only the top‐ranking queen lays eggs (“functional monogyny”). In contrast, queens in colonies from extended coniferous forests throughout the Palaearctic rarely interact aggressively and all lay eggs (“polygyny”). An experimental increase of queen:worker ratios in colonies from low‐skew populations elicits queen–queen aggression similar to that in functionally monogynous populations. Here, we show that this manipulation also results in increased reproductive inequalities among queens. Queens from natural overwintering colonies differed in the number of developing oocytes in their ovaries. These differences were greatly augmented in queens from colonies with increased queen:worker ratios relative to colonies with a low queen:worker ratio. As assumed by models of reproductive skew, L. acervorum colonies thus appear to be capable of flexibly adjusting reproductive skew to social conditions, yet in the opposite way than predicted by most models.

Workers respond to unequal likelihood of future reproductive opportunities in an ant

In cooperatively breeding or eusocial societies, opportunities may arise for helper individuals to gain direct fitness by reproducing. However, the extent to which helpers respond differentially, in terms of their reproductive behaviour, to the probability that reproductive opportunities will arise is not fully known. In many eusocial Hymenoptera, workers lay eggs only in queenless conditions following the death of the queen or queens. Relative to polygyny (multiple queens per colony), monogyny (single queen per colony) increases the probability that queenless conditions arise. We therefore tested the hypothesis that ant workers respond differentially to queenless conditions as a function of the probability of queenlessness. We compared worker behaviour and reproduction before and after removal of queens from monogynous and polygynous colonies of the ant Leptothorax acervorum . We found that, in queenless conditions, workers from monogynous colonies were significantly more likely to lay eggs, showed a significantly reduced latency to egg laying and laid eggs at a significantly higher rate per capita than workers from polygynous colonies. In addition, before queen removal, workers that laid eggs in queenless conditions across both monogynous and polygynous colonies performed a range of behaviours associated with reproduction at significantly higher rates than nonreproductive, control workers. These ‘future reproductive’ workers also significantly reduced their rates of brood care following queen removal. These findings show that workers under monogyny reproduce more readily in queenless conditions than workers under polygyny, and that would-be reproductive workers alter their behaviour before they experience the opportunity for future reproduction. They therefore suggest that workers adaptively modulate their reproductive behaviour as a function of the likelihood of opportunities for direct reproduction arising, and that workers' behaviour is affected by the ability to gain direct fitness even when reproduction is currently not occurring. • We removed all queens from single- and multiple-queen ant colonies. • We monitored the extent of worker egg laying in queenless conditions. • Workers previously under single queens were significantly more reproductive. • Workers laying eggs when queenless differed behaviourally before queen removal. • Results suggest workers respond adaptively to the likelihood of future reproduction.

Age and ovarian development are related to worker personality and task allocation in the ant Leptothorax acervorum

Abstract In social insects, workers of different morphological castes and age are known to act differently. Yet, it is unclear how body size and ovarian development influence worker personalities (i.e. consistent behavioral variation) and task allocation in similar aged ant workers of monomorphic species. Behavioral variation is thought to be a key element of division of labor, but few studies have linked worker personality to task allocation. We investigated individual behavior in Leptothorax acervorum ant workers at two time points during the first three months of their life and in two different settings. We observed worker behavior in the nest (i.e. task allocation) and in standardized aggression, exploration and brood care experiments (i.e. personality) and found behavioral repeatability in foraging and exploration. Further, workers acted consistently across settings: workers with a more aggressive and exploratory personality type were more active in the nest. Moreover, ovarian development was associated with worker personality and task allocation: older workers with well-developed ovaries foraged less, but were more aggressive and exploratory. In accordance with the typical age-polyethism of social insects, workers became more active and foraged more as they grew older. Consequently, our study suggests that task allocation in Leptothorax acervorum is not only influenced by ovarian development and age, but moreover by the personalities of its workers.

Behavioral plasticity in ant queens: environmental manipulation induces aggression among normally peaceful queens in the socially polymorphic ant Leptothorax acervorum.

The behavioral traits that shape the structure of animal societies vary considerably among species but appear to be less flexible within species or at least within populations. Populations of the ant Leptothorax acervorum differ in how queens interact with other queens. Nestmate queens from extended, homogeneous habitats tolerate each other and contribute quite equally to the offspring of the colony (polygyny: low reproductive skew). In contrast, nestmate queens from patchy habitats establish social hierarchies by biting and antennal boxing, and eventually only the top-ranking queen of the colony lays eggs (functional monogyny: high reproductive skew). Here we investigate whether queen-queen behavior is fixed within populations or whether aggression and high skew can be elicited by manipulation of socio-environmental factors in colonies from low skew populations. An increase of queen/worker ratio and to a lesser extent food limitation elicited queen-queen antagonism in polygynous colonies from Nürnberger Reichswald similar to that underlying social and reproductive hierarchies in high-skew populations from Spain, Japan, and Alaska. In manipulated colonies, queens differed more in ovarian status than in control colonies. This indicates that queens are in principle capable of adapting the magnitude of reproductive skew to environmental changes in behavioral rather than evolutionary time.

Absence of Within‐Colony Kin Discrimination in a Multiple‐Queen Ant, Leptothorax acervorum

AbstractInclusive fitness theory predicts that, other things equal, individuals within social groups should direct altruistic behaviour towards their most highly related group‐mates to maximise indirect fitness benefits. In the social insects, most previous studies have shown that within‐colony kin discrimination (nepotism) is absent or weak. However, the number of studies that have investigated within‐colony kin discrimination at the level of individual behaviour remains relatively small. We tested for within‐colony kin discrimination in the facultatively multiple‐queen (polygynous) ant, Leptothorax acervorum. Specifically, we tested whether workers within polygynous colonies treated queens differently as a function of their relatedness to them. Colonies containing two egg‐laying queens were filmed to measure the rate at which individually marked workers antennated and groomed or fed each queen. Relatedness between individual queens and workers was calculated from their genotypes at four microsatellite loci. The results showed there were no differences in the rates at which workers antennated or groomed/fed their more related queen and their less related queen. Workers interacted preferentially with their potential mother queen with respect to grooming/feeding but not with respect to antennation. However, because of high queen turnover, the frequency of adult workers with their potential mother queen still present within the colony was relatively low. Overall, therefore, we found no evidence for within‐colony kin discrimination in the context of the average worker's treatment of queens in polygynous L. acervorum colonies.

Distribution of Ants (Insecta, Hymenoptera) in Chiaksan Mountain, Prov. Gangweon, Korea

To survey the appearance pattern of ants in Mt. Chiaksan, 1,358 colonies 0f ant species were collected in three courses for two years (2009~2010). As the result, the ant fauna of Mt. Chiaksan were found to be 57 species belonging to 27 genera under 6 subfamilies. Among them, 15 species were newly recorded to inhabit in Mt. Chiaksan: Pachycondyla chinensis, P. pilosior, Hypoponera gleadowi, Proceratium itoi, Myrmica kotokui, M. kurokii, Stenamma ussuriensis, Leptothorax acervorum, Monomorium chinense, Mo. intrudens, Crematogaster vagulla, Camponotus vitiosus, Formica sanguinea, F. yessensis, and Lasius umbratus. Consequently a total of 60 species under 27 genera of Formicidae are recorded from Mt. Chiaksan.

Creativity and Autonomy in Swarm Intelligence Systems

This work introduces two swarm intelligence algorithms—one mimicking the behaviour of one species of ants (Leptothorax acervorum) foraging (a ‘stochastic diffusion search’, SDS) and the other algorithm mimicking the behaviour of birds flocking (a ‘particle swarm optimiser’, PSO)—and outlines a novel integration strategy exploiting the local search properties of the PSO with global SDS behaviour. The resulting hybrid algorithm is used to sketch novel drawings of an input image, exploiting an artistic tension between the local behaviour of the ‘birds flocking’—as they seek to follow the input sketch—and the global behaviour of the ‘ants foraging’—as they seek to encourage the flock to explore novel regions of the canvas. The paper concludes by exploring the putatve ‘creativity’ of this hybrid swarm system in the philosophical light of the ‘rhizome’ and Deleauze’s well-known ‘Orchid and Wasp’ metaphor.

Specific ant-pollination in an alpine orchid and the role of floral scent in attracting pollinating ants

Several studies have recently shown that floral scent can deter ants from flowers. However, when ants serve as reliable pollen vectors, for example in harsh, windy habitats, were flying insects are less active, plants should have evolved floral signals to attract them to the flowers. We tested this hypothesis in the alpine orchid, Chamorchis alpina. C. alpina was found to be predominantly ant pollinated, with some occasional pollination by ichneumonid wasps. In all three investigated populations, only two species of ants, Formica lemani and Leptothorax acervorum visited the flowers and removed pollinaria. These two pollinator ants were found to be among the most common ant species in all habitats, but other, non-pollinating ants were also frequently found, suggesting a factor that mediates specific pollination. Floral morphology was found to be compatible with at least one of the common non-pollinator ants. Floral scent consistently comprised five terpenoid compounds, β-phellandrene, 1,8-cineole, linalool, α-terpineol, and β-caryophyllene. A synthetic blend of these five compounds emitting from rubber septa, was found to be attractive to one pollinator ant-species, F. lemani, in the field. The floral scent of C. alpina, through attracting only specific ants, may thus play a role in filtering floral visitors.

Workers determine queen inheritance of reproduction in a functionally monogynous ant population

In cooperatively breeding animals there is potential for conflict among group members over reproductive sharing (skew). The outcome of such conflict depends on which individuals have power. Theoretical treatments of skew generally assume that power rests with those directly reproducing, but in eusocial insects, an important group for testing skew theory, nonreproductive workers are known to be influential in other colony conflicts such as sex ratio. We investigated the role of queens and workers in determining queen inheritance of a newly vacant reproductive position in a functionally monogynous (only one queen reproduces) population of the ant Leptothorax acervorum. Multiple-queen colonies with an already established reproductive queen were split in half producing a fragment containing multiple, previously nonreproductive queens. Loss of the established queen simulates a queen turnover event as occurs in nature. We found that worker behaviour influenced which queen filled the vacant reproductive position, with this queen receiving on average less aggression and more grooming from workers than the other queens. This study shows that after loss of the established queen, workers can modify their behaviour towards individual queens, and, contrary to skew models, skew among queens remains high despite changes in relatedness asymmetry. Our results suggest workers collectively hold considerable power over skew among queens.

No evidence of volatile chemicals regulating reproduction in a multiple queen ant

Efficient cooperation in eusocial insect colonies requires effective communication, and there is abundant evidence of non-volatile chemicals playing a role in regulating reproduction within colonies. In contrast, there have been fewer studies investigating the role of volatile chemicals. This study investigated the potential role of volatile chemicals in regulating queen reproduction either by directly inhibiting queen reproduction or by honestly signalling queen fecundity to workers. We tested this using multiple queen colonies of the ant (Leptothorax acervorum) from a functionally monogynous population where one queen monopolizes all reproduction. Nine colonies, each with an established laying queen, were split to produce two colony fragments-one containing the reproducing queen (group 1) and one containing only previously non-reproducing queens (group 2). Each group was separated by a fine wire mesh preventing physical contact, but allowing volatile chemical contact. In each group 2 fragment, we found that a single formerly non-reproductive queen commenced reproduction and that the rate of egg laying and maximum number of eggs recorded did not significantly differ between groups 1 and 2, results that do not support volatile chemicals as playing a role in regulating queen reproduction. Instead, our findings suggest that physical contact is necessary to maintain functional monogyny.

Queen dominance and worker policing control reproduction in a threatened ant

BackgroundEfficient division of reproductive labor is a crucial characteristic of social insects and underlies their ecological and evolutionary success. Despite of the harmonious appearance of insect societies, nestmates may have different interests concerning the partitioning of reproduction among group members. This may lead to conflict about reproductive rights. As yet, few studies have investigated the allocation of reproduction among queens in multi - queen societies ("reproductive skew"). In the ant Leptothorax acervorum, reproductive skew varies considerably among populations. While reproduction is quite equally shared among nestmate queens in most populations from boreal Eurasia (low skew), colonies from populations at the edge of the species' range are characterized by "functional monogyny," i.e., high skew. The proximate mechanisms underlying high skew, in particular how workers influence which queen lays eggs, are not well understood. We investigated the behavior of queens and workers in functionally monogynous colonies of L. acervorum from two mountain ranges in central Spain.ResultsWe provide evidence for both queen and worker influence on the outcome of conflict over reproduction in colonies of L. acervorum from Spain. The patterns of queen - queen aggression and worker - queen grooming and feeding after hibernation allowed predicting, which queen later began to lay eggs. In contrast, worker aggression towards queens was not clearly associated with a queen's future reproductive success. Queen - queen and worker - queen aggression differed in quality: queens typically engaged in ritualized dominance behavior, such as antennal boxing, while workers also attacked queens by biting and prolonged pulling on their legs and antennae. In several cases, overt worker aggression led to the expulsion of queens from the nest or their death.ConclusionWe conclude that queens of L. acervorum from Spain establish rank orders by ritualized dominance interactions, such as antennal boxing. Workers may reinforce these hierarchies by preferentially feeding and grooming high ranking queens and attacking lower ranking queens. Aggressive worker policing may thus stabilize functional monogyny. Optimal skew models predict that high skew in ants is associated with high dispersal costs. In central Spain, L. acervorum is restricted to small patches at higher elevations, which presumably makes dispersal and colony founding difficult. Because of the ecological requirements of L. acervorum and the predicted large impact of global change on central Spain, the functionally monogynous populations of this ant must be considered as threatened.

Trophic relationships of grassland ants based on stable isotopes

As keystone species in many ecosystems, ants are important predators of insects and other invertebrates, which are fed mainly to the ant larvae. Honeydew is important in the diet of adult worker ants and some ant species collect seeds as food items. Differences in the natural abundance ratios of the stable isotopes of carbon and nitrogen were used to investigate the trophic relationships of eight species of ants in limestone grassland near Limerick, mid-west Ireland. During July 2005, samples of adult workers and larvae were collected from ten nests of each of eight sympatric species ( Myrmica ruginodis , M. scabrinodis , M. sabuleti, M. schencki, Leptothorax acervorum, Lasius flavus , L. niger , and Formica lemani) and analysed using Elemental Analysis–Isotope Ratio Mass Spectrometry (EA–IRMS). Myrmica ruginodis workers had the highest δ 15 N, and M. schencki the lowest δ 15 N. The δ 15 N spacing between these two species was 2.6‰, which represents a difference of almost one trophic level. High δ 15 N values for adult Lasius flavus were unexpected as they suggest a more predatory diet for L. flavus workers than is implied in the literature, or possibly a diet including Collembola which can have higher δ 15 N values than herbivorous arthropods. The results for Formica lemani indicate that its diet is more generalist than field observations and the literature suggest. The larvae of L. acervorum had the lowest values for δ 15 N and δ 13 C (probably reflecting a high lipid content) and the values for the workers were also low, suggesting that the food sources of this species, which are little known, are different from those of the other co-occurring ant species in the study.

Genetic diversity, population structure and sex‐biased dispersal in three co‐evolving species

Genetic diversity and spatial structure of populations are important for antagonistic coevolution. We investigated genetic variation and population structure of three closely related European ant species: the social parasite Harpagoxenus sublaevis and its two host species Leptothorax acervorum and Leptothorax muscorum. We sampled populations in 12 countries and analysed eight microsatellite loci and an mtDNA sequence. We found high levels of genetic variation in all three species, only slightly less variation in the host L. muscorum. Using a newly introduced measure of differentiation (Jost's D(est)), we detected strong population structuring in all species and less male-biased dispersal than previously thought. We found no phylogeographic patterns that could give information on post-glacial colonization routes - northern populations are as variable as more southern populations. We conclude that conditions for Thompson's geographic mosaic of coevolution are ideal in this system: all three species show ample genetic variation and strong population structure.

Population structure and the co‐evolution between social parasites and their hosts

Co-evolutionary trajectories of host-parasite interactions are strongly affected by the antagonists' evolutionary potential, which in turn depends on population sizes as well as levels of recombination, mutation, and gene flow. Under similar selection pressures, the opponent with the higher evolutionary rate is expected to lead the co-evolutionary arms race and to develop local adaptations. Here, we use mitochondrial DNA sequence data and microsatellite markers to assess the amount of genetic variability and levels of gene flow in two host-parasite systems, each consisting of an ant social parasite--the European slavemaker Harpagoxenus sublaevis and the North American slavemaker Protomognathus americanus--and its two main host species. Our population genetic analyses revealed limited gene flow between individual populations of both host and parasite species, allowing for a geographic mosaic of co-evolution. In a between-system comparison, we found less genetic variability and more pronounced structure in Europe, where previous behavioural studies demonstrated strong local adaptation. Within the European host-parasite system, the larger host species Leptothorax acervorum exhibited higher levels of both genetic variability and gene flow, and previous field data showed that it is less affected by the social parasite H. sublaevis than the smaller host Leptothorax muscorum, which has genetically depleted and isolated populations. In North America, the parasite P. americanus showed higher levels of gene flow between sites, but overall less genetic diversity than its hyper-variable main host species, Temnothorax longispinosus. Interestingly, recent ecological and chemical studies demonstrated adaptation of P. americanus to local host populations, indicating the importance of migration in co-evolutionary interactions.