title: Phylogenetic and cophylogenetic relationships of entomopathogenic nematodes (Heterorhabditis: Rhabditida) and their symbiotic bacteria (Photorhabdus: Enterobacteriaceae).
abstract: Mutualistic association between entomopathogenic Photorhabdus bacteria and Heterorhabditis nematodes represents one of the emerging model systems in symbiosis studies, yet little is known about this partnership from a coevolutionary perspective. Herein, we investigated phylogenetic and cophylogenetic relationships of Heterorhabditis and Photorhabdus strains using molecular markers Internal Transcribed Spacer and gyrase B gene sequences, respectively. The phylogenies presented consistent, well supported, monophyletic groups in the parsimonious and likelihood analyses for both the nematode and bacterial strains and supported the placement of currently recognized taxa, from which a potentially new Heterorhabditis species represented by a Thailand strain MP68 was identified. While the nematode strains with distant geographic distributions showed no detectable phylogenetic divergence within H. bacteriophora or H. georgiana monophyletic groups, their respective symbiotic bacteria speciated into two Photorhabdus species: P. luminescens and P. temperata, indicating the occurrence of duplication. Although such evolutionary process reduces the phylogenetic congruence between Heterorhabditis nematodes and Photorhabdus bacteria, global cophylogenetic tests using ParaFit detected a highly significant correlation between the two phylogenies (ParaFitGlobal = 0.001). Further, the associations between H. zealandica, H. indica and H. megidis strains and their symbiotic bacteria exhibited significant contribution to the overall cophylogenetic structure. Overall, this study reveals evidence of coevolution between Photorhabdus bacteria and Heterorhabditis nematodes and provides a framework for further examination of the evolution of these associations.
authors.affiliation: Department of Entomology, The Ohio State University, OARDC, Wooster, OH 44691, USA.
authors.forename: Patchareewan
authors.initials: P
authors.lastname: Maneesakorn
authors.forename: Ruisheng
authors.initials: R
authors.lastname: An
authors.forename: Hannah
authors.initials: H
authors.lastname: Daneshvar
authors.forename: Kara
authors.initials: K
authors.lastname: Taylor
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Bai
authors.forename: Byron J
authors.initials: BJ
authors.lastname: Adams
authors.forename: Parwinder S
authors.initials: PS
authors.lastname: Grewal
authors.forename: Angsumarn
authors.initials: A
authors.lastname: Chandrapatya
mesh_terms: D000818:Animals; D001483:Base Sequence; D027081:DNA Gyrase / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D049810:Genetic Speciation; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020637:Photorhabdus / Q000235:genetics*; D010802:Phylogeny; D017168:Rhabditida / Q000235:genetics* / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D017931:DNA Primers; D021903:DNA, Ribosomal Spacer; D027081:DNA Gyrase