title: Complex phylogeographic patterns in the freshwater alga Synura provide new insights into ubiquity vs. endemism in microbial eukaryotes.
abstract: The global distribution, abundance, and diversity of microscopic freshwater algae demonstrate an ability to overcome significant barriers such as dry land and oceans by exploiting a range of biotic and abiotic colonization vectors. If these vectors are considered unlimited and colonization occurs in proportion to population size, then globally ubiquitous distributions are predicted to arise. This model contrasts with observations that many freshwater microalgal taxa possess true biogeographies. Here, using a concatenated multigene data set, we study the phylogeography of the freshwater heterokont alga Synura petersenii sensu lato. Our results suggest that this Synura morphotaxon contains both cosmopolitan and regionally endemic cryptic species, co-occurring in some cases, and masked by a common ultrastructural morphology. Phylogenies based on both proteins (seven protein-coding plastid and mitochondrial genes) and DNA (nine genes including ITS and 18S rDNA) reveal pronounced biogeographic delineations within phylotypes of this cryptic species complex while retaining one clade that is globally distributed. Relaxed molecular clock calculations, constrained by fossil records, suggest that the genus Synura is considerably older than currently proposed. The availability of tectonically relevant geological time (10⁷-10⁸ years) has enabled the development of the observed, complex biogeographic patterns. Our comprehensive analysis of freshwater algal biogeography suggests that neither ubiquity nor endemism wholly explains global patterns of microbial eukaryote distribution and that processes of dispersal remain poorly understood.
authors.forename: Sung Min
authors.initials: SM
authors.lastname: Boo
authors.forename: Han Soon
authors.initials: HS
authors.lastname: Kim
authors.forename: Woongghi
authors.initials: W
authors.lastname: Shin
authors.forename: Ga Hun
authors.initials: GH
authors.lastname: Boo
authors.forename: Sung Mi
authors.initials: SM
authors.lastname: Cho
authors.forename: Bok Yeon
authors.initials: BY
authors.lastname: Jo
authors.forename: Jee-Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Eun Chan
authors.initials: EC
authors.lastname: Yang
authors.forename: Peter A
authors.initials: PA
authors.lastname: Siver
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Wolfe
authors.forename: Debashish
authors.initials: D
authors.lastname: Bhattacharya
authors.forename: Robert A
authors.initials: RA
authors.lastname: Andersen
authors.forename: Hwan Su
authors.initials: HS
authors.lastname: Yoon
mesh_terms: D021903:DNA, Ribosomal Spacer / Q000235:genetics; D005580:Fossils; D005618:Fresh Water; D016013:Likelihood Functions; D010802:Phylogeny; D058974:Phylogeography; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D056910:Republic of Korea; D017422:Sequence Analysis, DNA; D058009:Stramenopiles / Q000235:genetics*
chemical_list: D021903:DNA, Ribosomal Spacer; D012337:RNA, Ribosomal, 18S