title: Deep-Time Convergence in Rove Beetle Symbionts of Army Ants.
abstract: Recent adaptive radiations provide striking examples of convergence [1-4], but the predictability of evolution over much deeper timescales is controversial, with a scarcity of ancient clades exhibiting repetitive patterns of phenotypic evolution [5, 6]. Army ants are ecologically dominant arthropod predators of the world's tropics, with large nomadic colonies housing diverse communities of socially parasitic myrmecophiles [7]. Remarkable among these are many species of rove beetle (Staphylinidae) that exhibit ant-mimicking "myrmecoid" body forms and are behaviorally accepted into their aggressive hosts' societies: emigrating with colonies and inhabiting temporary nest bivouacs, grooming and feeding with workers, but also consuming the brood [8-11]. Here, we demonstrate that myrmecoid rove beetles are strongly polyphyletic, with this adaptive morphological and behavioral syndrome having evolved at least 12 times during the evolution of a single staphylinid subfamily, Aleocharinae. Each independent myrmecoid clade is restricted to one zoogeographic region and highly host specific on a single army ant genus. Dating estimates reveal that myrmecoid clades are separated by substantial phylogenetic distances-as much as 105 million years. All such groups arose in parallel during the Cenozoic, when army ants diversified into modern genera [12] and rose to ecological dominance [13, 14]. This work uncovers a rare example of an ancient system of complex morphological and behavioral convergence, with replicate beetle lineages following a predictable phenotypic trajectory during their parasitic adaptation to host colonies.
authors.affiliation: The Kyushu University Museum, Hakozaki 6-10-1, Fukuoka-shi, Fukuoka 812-8581, Japan.
authors.forename: Munetoshi
authors.initials: M
authors.lastname: Maruyama
authors.affiliation: Department of Genetics and Development, Columbia University, 701 West 168(th) Street, New York, NY 10032, USA; Division of Invertebrate Zoology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA. Electronic address: jp2488@columbia.edu.
authors.forename: Joseph
authors.initials: J
authors.lastname: Parker
mesh_terms: D000818:Animals; D001000:Ants / Q000469:parasitology / Q000502:physiology*; D005075:Biological Evolution; D001517:Coleoptera / Q000145:classification / Q000502:physiology*; D010802:Phylogeny; D013559:Symbiosis
keywords: Staphylinidae; army ants; convergent evolution; myrmecophily; social parasitism; symbiosis