title: Historical biogeography of the North American glacier ice worm, Mesenchytraeus solifugus (Annelida: Oligochaeta: Enchytraeidae).
abstract: North American ice worms are the largest glacially-obligate metazoans, inhabiting coastal, temperate glaciers between southcentral Alaska and Oregon. We have collected ice worm specimens from 10 new populations, completing a broad survey throughout their geographic range. Phylogenetic analyses of 87 individuals using fragments of nuclear 18S rRNA, and mitochondrial 12S rRNA and cyctochrome c oxidase subunit 1 (CO1) identified 18 CO1 haplotypes with divergence values up to ~10%. Phylogeographic interpretations suggest a St. Elias Range, Alaskan ancestry from an aquatic mesenchytraeid oligochaete during the early-Pliocene. A gradual, northward expansion by active dispersal from the central St. Elias clade characterizes a northern clade that is confined to Alaska (with one exception on Vancouver Island, British Columbia), while a distinct southern clade representing worms from British Columbia, Washington and Oregon was likely founded by a passive dispersal event originating from a northern ancestor. The geographic boundary between central and southern clades coincides with an ice worm distribution gap located in southern Alaska, which appears to have restricted active gene flow throughout the species' evolutionary history.
authors.affiliation: Department of Environmental Science, 4101 University Drive, Alaska Pacific University, Anchorage, AK 99508, USA.
authors.forename: C
authors.initials: C
authors.lastname: Roman Dial
authors.forename: Roman J
authors.initials: RJ
authors.lastname: Dial
authors.forename: Ralph
authors.initials: R
authors.lastname: Saunders
authors.forename: Shirley A
authors.initials: SA
authors.lastname: Lang
authors.forename: Ben
authors.initials: B
authors.lastname: Lee
authors.forename: Peter
authors.initials: P
authors.lastname: Wimberger
authors.forename: Megan S
authors.initials: MS
authors.lastname: Dinapoli
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Egiazarov
authors.forename: Shannon L
authors.initials: SL
authors.lastname: Gipple
authors.forename: Melanie R
authors.initials: MR
authors.lastname: Maghirang
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Swartley-McArdle
authors.forename: Stephanie R
authors.initials: SR
authors.lastname: Yudkovitz
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Shain
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D002170:Canada; D003576:Electron Transport Complex IV / Q000235:genetics; D051456:Gene Flow; D049810:Genetic Speciation; D016013:Likelihood Functions; D008957:Models, Genetic; D009835:Oligochaeta / Q000235:genetics*; D010802:Phylogeny; D058974:Phylogeography; D012335:RNA, Ribosomal / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D014481:United States
chemical_list: D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; C075526:RNA, ribosomal, 12S; D003576:Electron Transport Complex IV