Christian Rabeling

• Ph.D.
• Arizona State University

Ants are a globally distributed and highly diverse group of eusocial animals, playing key ecological roles in most of the world’s terrestrial ecosystems. Our understanding of the processes involved in the evolution of this diverse family is contingent upon our knowledge of the phylogeny of the ants. While relationships among most subfamilies have c...

Accurately delimiting species boundaries is essential for understanding biodiversity. Here, we assessed the taxonomy of the leaf‐cutting ants in the Acromyrmex octospinosus (Reich) species complex using an integrative approach incorporating morphological, population genetic, phylogenetic and biogeographical data. We sampled populations across the b...

Social parasitism, where one social species parasitically depends on the other for survival and reproduction, is a highly successful life history strategy, especially in the eusocial Hymenoptera. In ants alone, more than 400 species of socially parasitic species exist and multiple forms of social parasitism evolved independently and convergently. Y...

Fungus-farming ants cultivate multiple lineages of fungi for food, but, because fungal cultivar relationships are largely unresolved, the history of fungus-ant coevolution remains poorly known. We designed probes targeting >2000 gene regions to generate a dated evolutionary tree for 475 fungi and combined it with a similarly generated tree for 276...

Ants are a globally distributed and highly diverse group of eusocial animals, playing key ecological roles in most of the world’s terrestrial ecosystems. Our understanding of the processes involved in the evolution this diverse family is contingent upon our knowledge of the phylogeny of the ants. While relationships among most subfamilies have come...

Four new inquiline social parasites are described in the dolichoderine ant genus Tapinoma from the Nearctic region, and keys are provided for queens and males of the Nearctic Tapinoma species. The new social parasite species represent the first inquiline species in the genus Tapinoma and the first confirmed inquilines known from the ant subfamily D...

Parasitism is ubiquitous across the tree of life, and parasites comprise approximately half of all animal species. Social insect colonies attract many pathogens, endo- and ectoparasites, and are exploited by social parasites, which usurp the social environment of their hosts for survival and reproduction. Exploitation by parasites and pathogens ver...

Studying the historical biogeography and life history transitions from eusocial colony life to social parasitism contributes to our understanding of the evolutionary mechanisms generating biodiversity in eusocial insects. The ants in the genus Myrmecia are a well-suited system for testing evolutionary hypotheses about how their species diversity wa...

Social parasites exploit the brood care behavior of their hosts to raise their own offspring. Social parasites are common among eusocial Hymenoptera and exhibit a wide range of distinct life history traits in ants, bees, and wasps. In ants, obligate inquiline social parasites are workerless (or nearly-so) species that engage in lifelong interaction...

The evolution of eusociality has allowed ants to become one of the most conspicuous and ecologically dominant groups of organisms in the world. A large majority of the current ∼14,000 ant species belong to the formicoids,¹ a clade of nine subfamilies that exhibit the most extreme forms of reproductive division of labor, large colony size,² worker p...

The prevalent mode of reproduction among ants is arrhenotokous parthenogenesis where unfertilized eggs give rise to haploid males and fertilized eggs develop into diploid females. Some ant species are capable of thelytokous parthenogenesis, a type of asexual reproduction where females develop from unfertilized diploid eggs. Thelytoky is well-docume...

Insect societies vary greatly in their social structure, mating biology, and life history. Polygyny, the presence of multiple reproductive queens in a single colony, and polyandry, multiple mating by females, both increase the genetic variability in colonies of eusocial organisms, resulting in potential reproductive conflicts. The co-occurrence of...

Significance Identifying the conditions associated with a life history transition from cooperative colony life to exploitative social parasitism is important for understanding how changes in behavior contribute to speciation. To explore the evolutionary origins of social parasitism, we reconstructed the evolutionary history of Formica ants because...

Atta Fabricius is an ecologically dominant leaf-cutting ant genus, the major herbivore of the Neotropics, and an agricultural pest of great economic importance. Phylogenetic relationships within Atta have until now remained uncertain, and the delimitation and identification of a subset of Atta species are problematic. To address these phylogenetic...

Supergenes, regions of the genome with suppressed recombination between sets of functional mutations, contribute to the evolution of complex phenotypes in diverse systems. Excluding sex chromosomes, most supergenes discovered so far appear to be young, being found in one species or a few closely related species. Here, we investigate how a chromosom...

Inquiline ants are highly specialized and obligate social parasites that infiltrate and exploit colonies of closely related species. They have evolved many times convergently, are often evolutionarily young lineages, and are almost invariably rare. Focusing on the leaf-cutting ant genus Acromyrmex , we compared genomes of three inquiline social par...

The New World ant genus Myrmecocystus Wesmael, 1838 (Formicidae: Formicinae: Lasiini) is endemic to arid and semi-arid habitats of the western United States and Mexico. Several intriguing life history traits have been described for the genus, the best-known of which are replete workers, that store liquified food in their largely expanded crops and...

Studying the behavioral and life history transitions from a cooperative, eusocial life history to exploitative social parasitism allows for deciphering the conditions under which changes in behavior and social organization lead to diversification. The Holarctic ant genus Formica is ideally suited for studying the evolution of social parasitism beca...

The non-leaf-cutting fungus-growing ants deposited in two entomological collections in Colombia were curated and identified to assess their diversity in the country. We examined 680 specimens, identifying 41 species belonging to seven genera, bringing the total of fungus-growing ant species known from Colombia to 85. The following species are new r...

In ants, social parasitism is an umbrella term describing a variety of life-history strategies, where a parasitic species depends entirely on a free-living species, for part of or its entire life-cycle, for either colony founding, survival, and/or reproduction. The highly specialized inquiline social parasites are fully dependent on their hosts for...

The fungus-growing ants and their fungal cultivars constitute a classic example of a mutualism that has led to complex coevolutionary dynamics spanning c. 55-65 Ma. Of the five agricultural systems practised by fungus-growing ants, higher-attine agriculture, of which leaf-cutter agriculture is a derived subset , remains poorly understood despite it...

Ant inquiline social parasites obligately depend on their hosts for survival and reproduction. Because of their shift from a eusocial to a socially parasitic life history, inquiline social parasites are interesting study systems for exploring the dynamics between conflict and cooperation in eusocial insect colonies. In addition, inquiline social pa...

Knowledge of the internal phylogeny and evolutionary history of ants (Formicidae), the world's most species-rich clade of eusocial organisms, has dramatically improved since the advent of molecular phylogenetics. A number of relationships at the subfamily level, however, remain uncertain. Key unresolved issues include placement of the root of the a...

Evolutionary adaptations for maintaining beneficial microbes are hallmarks of mutualistic evolution. Fungus-farming “attine” ant species have complex cuticular modifications and specialized glands that house and nourish antibiotic-producing Actinobacteria symbionts, which in turn protect their hosts’ fungus gardens from pathogens. Here we reconstru...

Xerolitor, a new, monotypic genus of fungus‐growing ants, is described to accommodate the phylogenetically isolated, relict species Mycetosoritis explicatus Kempf. We also diagnose the male and the larva of Xerolitor explicatus (Kempf) comb.n. and report ecological observations for the species, including nest architecture and foraging behaviour. Xe...

Over 40 years ago, the dacetine ant Strumigenys arizonica was discovered in a nest of the fungus-growing ant Trachymyrmex arizonensis at Madera Canyon in the Santa Rita Mountains of the southwestern United States. This discovery suggested that the two species form compound nests, but this hypothesis has not been investigated. Here, we characterize...

Leafcutter ants propagate co-evolving fungi for food. The nearly 50 species of leafcutter ants (Atta, Acromyrmex) range from Argentina to the USA, with the greatest species diversity in southern South America. We elucidate the biogeography of fungi cultivated by leafcutter ants using DNA-sequence and microsatellite-marker analyses of 474 cultivars...

Knowledge of the internal phylogeny and evolutionary history of ants (Formicidae), the world’s most species-rich clade of eusocial organisms, has dramatically improved since the advent of molecular phylogenetics. A number of relationships at the subfamily level, however, remain uncertain. Key unresolved issues include placement of the root of the a...

Fungus-farming “attine” ant agriculture consists of five distinct agricultural systems characterized by a remarkable symbiont fidelity in which five phylogenetic groups of ants faithfully cultivate five phylogenetic groups of fungi. Across-system garden switching experiments result in colony decline and death, indicating that attine ant-fungus symb...

Citation: Rabeling C, Sosa-Calvo J, O'Connell LA, Coloma LA, Fernández F (2016) Lenomyrmex hoelldobleri: a new ant species discovered in the stomach of the dendrobatid poison frog, Oophaga sylvatica (Funkhouser). ZooKeys 618: 79–95. Abstract The ant genus Lenomyrmex was recently discovered and described from mid to high elevation rainforests in sou...

The attine ant-fungus agricultural symbiosis evolved over tens of millions of years, producing complex societies with industrial-scale farming analogous to that of humans. Here we document reciprocal shifts in the genomes and transcriptomes of seven fungus-farming ant species and their fungal cultivars. We show that ant subsistence farming probably...

Supplementary Figures 1 - 18, Supplementary Tables 1 - 29, Supplementary Methods and Supplementary References

Number of annotated fungal genes in each CAZy family

Gene/transcript accessions, ortholog assignments, and inferred positively selected gene families for the sequenced attine ants and fungal cultivars

Aim: We sought to reconstruct the biogeographical structure and dynamics of a hyperdiverse ant genus, Pheidole, and to test several predictions of the taxon cycle hypothesis. Using large datasets on Pheidole geographical distributions and phylogeny, we (1) inferred patterns of biogeographical modularity (clusters of areas with similar faunal compo...

Social parasites exploit the colony resources of social species to secure their own survival and reproduction. Social parasites are frequently studied as models for conflict and cooperation as well as for speciation. The eusocial Hymenoptera harbor a diverse array of socially parasitic species with idiosyncratic life history strategies, but it is p...

Ants that resemble Camponotus maculatus (Fabricius, 1782) present an opportunity to test the hypothesis that the origin of the Pacific island fauna was primarily New Guinea, the Philippines, and the Indo-Malay archipelago (collectively known as Ma-lesia). We sequenced two mitochondrial and four nuclear markers from 146 specimens from Pacific island...

Ants are among the world’s most destructive invaders, and Pacific Islands are particularly susceptible to invasion by non-native ant species. A species from the taxonomically problematic Pheidole flavens-complex is reported here for the first time from the southwestern Pacific. Specimens of the species reported here were collected November 2011 fro...

Obligate social parasites, or inquilines, exploit the colonies of free-living social species and evolved at least 80 times in ants alone. Most species of the highly specialized inquiline social parasites are rare, only known from one or very few, geographically isolated populations, and the sexual offspring of most inquiline species mates inside th...

Inquiline social parasitic ant species exploit colonies of other ant species mainly by producing sexual offspring that are raised by the host. Ant social parasites and their hosts are often close relatives (Emery’s rule), and two main hypotheses compete to explain the parasites’ evolutionary origins: (1) the interspecific hypothesis proposes an all...

Attine ants cultivate fungi as their most important food source and in turn the fungus is nourished, protected against harmful microorganisms, and dispersed by the ants. This symbiosis evolved approximately 50-60 million years ago in the late Paleocene or early Eocene, and since its origin attine ants have acquired a variety of fungal mutualists in...

We isolated and characterized a total of 22 microsatellite loci for the leafcutter ant, Acromyrmex lundii. The loci were screened for 24 individuals from southern Brazil and Uruguay. The number of alleles per locus ranged from 5 to 20, the observed heterozygosity ranged from 0.417 to 0.917, and the probability of identity values ranged from 0.011 t...

Obligate social parasites, or inquilines, exploit the colonies of free-living social species and evolved at least 80 times in ants alone. Most species of the highly specialized inquiline social parasites are rare, only known from one or very few, geographically isolated populations, and the sexual offspring of most inquiline species mates inside th...

We isolated and characterized a total of 22 microsatellite loci for the leafcutter ant, Acromyrmex lundii. The loci were screened for 24 individuals from southern Brazil and Uruguay. The number of alleles per locus ranged from 5 to 20, the observed heterozygosity ranged from 0.417 to 0.917, and the probability of identity values ranged from 0.011 t...

Cyatta abscondita, a new genus and species of fungus-farming ant from Brazil, is described based on morphological study of more than 20 workers, two dealate gynes, one male, and two larvae. Ecological field data are summarized, including natural history, nest architecture, and foraging behavior. Phylogenetic analyses of DNA sequence data from four...

Female parthenogenesis, or thelytoky, is particularly common in solitary Hymenoptera. Only more recently has it become clear that many eusocial species also regularly reproduce thelytokously, and here we provide a comprehensive overview. Especially in ants, thelytoky underlies a variety of idiosyncratic life histories with unique evolutionary and e...

In this natural history note we describe and illustrate the specialized predatory behavior of the ponerine ant Thaumatomyrmex paludis from the Brazilian Amazon. This study of T. paludis implies that specialized predation on polyxenid millipedes is widespread in the genus Thaumatomyrmex. The observation that one T. paludis forager only partly depila...

Sex and recombination are central processes in life generating genetic diversity. Organisms that rely on asexual propagation risk extinction due to the loss of genetic diversity and the inability to adapt to changing environmental conditions. The fungus-growing ant species Mycocepurus smithii was thought to be obligately asexual because only parthe...

Ant inquilines are obligate social parasites, usually lacking a sterile worker caste, which are dependent on their hosts for survival and reproduction. Social parasites are rare among the fungus-gardening ants (Myrmicinae: tribe Attini) and only four species are known until now, all being inquilines from the Higher Attini. We describe Mycocepurus c...

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The general prevalence of sexual reproduction over asexual reproduction among organisms testifies to the evolutionary benefits of recombination, such as accelerated adaptation to changing environments and elimination of deleterious mutations. Documented instances of asexual reproduction in groups otherwise dominated by sexual reproduction challenge...

Ants are the world's most conspicuous and important eusocial insects and their diversity, abundance, and extreme behavioral specializations make them a model system for several disciplines within the biological sciences. Here, we report the discovery of a new ant that appears to represent the sister lineage to all extant ants (Hymenoptera: Formicid...

We reassess the coevolution between actinomycete bacteria and fungus-gardening (attine) ants. Actinomycete bacteria are of special interest because they are metabolic mutualists of diverse organisms (e.g., in nitrogen-fixation or antibiotic production) and because Pseudonocardia actinomycetes are thought to serve disease-suppressing functions in at...

We revise and key Trachymyrmex ants occurring in North America north of Mexico. We recognize nine species, including one new species from southern Arizona: T. arizonensis (Wheeler), T. carinatus Mackay & Mackay, T. desertorum (Wheeler), T. jamaicensis (André), T. nogalensis Byars, T. pomonae Rabeling & Cover sp. nov., T. septentrionalis (McCook), T...

We revise and key Trachymyrmex ants occurring in North America north of Mexico. We recognize nine species, including one new species from southern Arizona: T. arizonensis (Wheeler), T. carinatus Mackay & Mackay, T. desertorum (Wheeler), T. jamaicensis (André), T. nogalensis Byars, T. pomonae Rabeling & Cover sp. nov., T. septentrionalis (McCook), T...

Nest architecture and demography of the non leaf-cutting fungus-growing ant species Mycocepurus goeldii and M. smithii (Attini: Formicidae) were studied in an agroforest habitat near Manaus, Brazil during the excavation of 13 nests. Both species built their nests in two different ways. The first type possessed a "tree-like" architecture, in which a...

Fungus-growing ants (Attini, Formicidae) originated about 45–65million years ago when forging a mutualistic association with basidiomycete fungi (Lepiotaceae). Here we use information on the biology of the non-leafcutting fungus-growing ants and their close relatives in the genus Blepharidatta to evaluate hypotheses for the evolutionary origin of f...