More Like this

1. Biogeography and evolution of social parasitism in Australian Myrmecia bulldog ants revealed by phylogenomics

   Mera-Rodríguez LD, Jourdan H (May 2023, Molecular phylogenetics and evolution)

   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 was assembled through time because the genus is endemic to Australia with the single exception of the species M. apicalis inhabiting the Pacific Island of New Caledonia, and because at least one social parasite species exists in the genus. However, the evolutionary mechanisms underlying the disjunct biogeographic distribution of M. apicalis and the life history transition(s) to social parasitism remain unexplored. To study the biogeographic origin of the isolated, oceanic species M. apicalis and to reveal the origin and evolution of social parasitism in the genus, we reconstructed a comprehensive phylogeny of the ant subfamily Myrmeciinae. We utilized Ultra Conserved Elements (UCEs) as molecular markers to generate a molecular genetic dataset consisting of 2,287 loci per taxon on average for 66 out of the 93 known Myrmecia species as well as for the sister lineage Nothomyrmecia macrops and selected outgroups. Our time-calibrated phylogeny inferred that: (i) stem Myrmeciinae originated during the Paleocene ~ 58 Ma ago; (ii) the current disjunct biogeographic distribution of M. apicalis was driven by long-distance dispersal from Australia to New Caledonia during the Miocene ~ 14 Ma ago; (iii) the single social parasite species, M. inquilina, evolved directly from one of the two known host species, M. nigriceps, in sympatry via the intraspecific route of social parasite evolution; and (iv) 5 of the 9 previously established taxonomic species groups are non-monophyletic. We suggest minor changes to reconcile the molecular phylogenetic results with the taxonomic classification. Our study enhances our understanding of the evolution and biogeography of Australian bulldog ants, contributes to our knowledge about the evolution of social parasitism in ants, and provides a solid phylogenetic foundation for future inquiries into the biology, taxonomy, and classification of Myrmeciinae. 

   more » « less
2. Multi-queen breeding is associated with the origin of inquiline social parasitism in ants

   https://doi.org/10.1038/s41598-022-17595-0  

   Dahan, Romain A.; Rabeling, Christian (December 2022, Scientific Reports)

   Abstract 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 interactions with their hosts, taking advantage of the existing host worker forces to reproduce and exploit host colonies’ resources. Inquiline social parasites are phylogenetically diverse with approximately 100 known species that evolved at least 40 times independently in ants. Importantly, ant inquilines tend to be closely related to their hosts, an observation referred to as ‘Emery’s Rule’. Polygyny, the presence of multiple egg-laying queens, was repeatedly suggested to be associated with the origin of inquiline social parasitism, either by providing the opportunity for reproductive cheating, thereby facilitating the origin of social parasite species, and/or by making polygynous species more vulnerable to social parasitism via the acceptance of additional egg-laying queens in their colonies. Although the association between host polygyny and the evolution of social parasitism has been repeatedly discussed in the literature, it has not been statistically tested in a phylogenetic framework across the ants. Here, we conduct a meta-analysis of ant social structure and social parasitism, testing for an association between polygyny and inquiline social parasitism with a phylogenetic correction for independent evolutionary events. We find an imperfect but significant over-representation of polygynous species among hosts of inquiline social parasites, suggesting that while polygyny is not required for the maintenance of inquiline social parasitism, it (or factors associated with it) may favor the origin of socially parasitic behavior. Our results are consistent with an intra-specific origin model for the evolution of inquiline social parasites by sympatric speciation but cannot exclude the alternative, inter-specific allopatric speciation model. The diversity of social parasite behaviors and host colony structures further supports the notion that inquiline social parasites evolved in parallel across unrelated ant genera in the formicoid clade via independent evolutionary pathways. 

   more » « less
3. Post K-Pg rise in ant and termite prevalence underlies convergent dietary specialization in mammals

   https://doi.org/10.1093/evolut/qpaf121  

   Vida, Thomas; Calamari, Zachary T; Barden, Phillip (July 2025, Evolution)

   Kaliontzopoulou, Antigoni; Morlon, Hélène (Ed.)

   Abstract Ants and termites are ubiquitous members of most modern terrestrial ecosystems. These insects act as agents of selection among plants and animals, driving ecological and evolutionary shifts in disparate groups across the tree of life. Obligate consumers of ants or termites, called myrmecophages, exhibit morphological adaptations such as lengthened tongues and reduced teeth that are associated with a bulk feeding strategy. Though a typifying feature of some mammal lineages, the macroevolutionary history of obligate myrmecophagy and its relationship to social insect evolution is unknown. We report large-scale patterns of myrmecophagous evolution through a synthesis of the social insect fossil record, ant and termite evolutionary history, and mammal natural history data spanning 4,099 species. Specialized ant and termite feeding has arisen at least 12 times in mammals and through multiple pathways; transitions to myrmecophagy stem from insectivorous and carnivorous ancestors. We recover one reversal out of social insect feeding, perhaps owing to food source stability or difficulty in regaining generalist features. Despite the contemporary ubiquity of social insects, their history suggests a recent capacity for specialist consumers. While both lineages originated in the Cretaceous, rising fossil prevalence of ants and termites and their acquisition of large colony sizes predominantly occurred in the Cenozoic. 

   more » « less
4. Broad host use and frequent polyandry in the facultative dulotic species Formica aserva (Hymenoptera: Formicidae)

   https://doi.org/10.1093/aesa/saae020  

   Scarparo, Giulia; West, Mari; Brelsford, Alan; Purcell, Jessica (August 2024, Annals of the Entomological Society of America)

   Knolhoff, Lisa (Ed.)

   Abstract The study of social parasitism faces numerous challenges arising from the intricate and intranidal host–parasite interactions and the rarity of parasites compared to their free-living counterparts. As a result, our understanding of the ecology and evolution of most social parasites remains limited. Using whole-genome and reduced-representation sequence data, we conducted a study to fill knowledge gaps on host use, colony social structure, and population genetics of the facultative dulotic ant Formica aserva Forel. Our study reveals the remarkable ability of F. aserva to exploit at least 20 different host species across its wide geographic distribution. In some cases, one social parasite colony exploits multiple hosts simultaneously, suggesting a high degree of generalization even at a local spatial scale. Approximately 80% of the colonies were monogyne (with a single queen), with many exhibiting higher rates of polyandry compared to most Formica ants. Although we identified a supergene on chromosome 3, its association with colony structure remains uncertain due to the rarity of polygyny in our sample. Population genetic analyses reveal substantial geographic population structure, with the greatest divergence between California populations and those from the rest of the range. Mitochondrial population structure differs from structure inferred from the nuclear genome on a broad geographic scale, suggesting a possible role of adaptive introgression or genetic drift. This study provides valuable insights into the ecology and evolution of F. aserva, underscoring the need for further research to decipher the complexities of host interactions and the genetic mechanisms that regulate social structure. 

   more » « less
5. Unexpected absence of a multiple-queen supergene haplotype from supercolonial populations of Formica ants

   https://doi.org/10.1093/jeb/voaf023  

   Lagunas-Robles, German; Alam, Zul; Brelsford, Alan (April 2025, Journal of Evolutionary Biology)

   Rogers, Rebekah; Larson, Erica (Ed.)

   Abstract Ants exhibit many complex social organization strategies. One particularly elaborate strategy is supercoloniality, in which a colony consists of many interconnected nests (= polydomy) with many queens (= polygyny). In many species of Formica ants, an ancient queen number supergene determines whether a colony is monogyne (= headed by single queen) or polygyne. The presence of the rearranged P haplotype typically leads colonies to be polygyne. However, the presence and function of this supergene polymorphism have not been examined in supercolonial populations. Here, we use genomic data from species in the Formica rufa group to determine whether the P haplotype leads to supercoloniality. In a Formica paralugubris population, we find that nests are polygyne despite the absence of the P haplotype in workers. We find spatial genetic ancestry patterns in nests consistent with supercolonial organization. Additionally, we find that the P haplotype is also absent in workers from supercolonial Formica aquilonia and Formica aquilonia × polyctena hybrid populations but is present in some Formica polyctena workers. We conclude that the P haplotype is not necessary for supercoloniality in the Formica rufa group, despite its long-standing association with non-supercolonial polygyny across the Formica genus. 

   more » « less