Assessing the evolutionary history of the class Synurophyceae (Heterokonta) using molecular, morphometric, and paleobiological approaches

Siver, Peter A.,Jo, Bok Yeon,Kim, Jong Im,Shin, Woongghi,Lott, Anne Marie,Wolfe, Alexander P. Botanical Society of America, Inc. (Columbus) * Bu 2015 American journal of botany Vol. No.

<P>• <I>Premise of the study:</I> Heterokont algae of the class Synurophyceae, characterized by distinctive siliceous scales that cover the surface of the cell, are ecologically important in inland waters, yet their evolutionary history remains enigmatic. We explore phylogenetic relationships within this group of algae relative to geologic time, with a focus on evolution of siliceous components.</P><P>• <I>Methods:</I> We combined an expansive five-gene and time-calibrated molecular phylogeny of synurophyte algae with an extensive array of fossil specimens from the middle Eocene to infer evolutionary trends within the group.</P><P>• <I>Key results:</I> The group originated in the Jurassic approximately 157 million years ago (Ma), with the keystone genera <I>Mallomonas</I> and <I>Synura</I> diverging during the Early Cretaceous at 130 Ma. <I>Mallomonas</I> further splits into two major subclades, signaling the evolution of the V-rib believed to aid in the spacing and organization of scales on the cell covering. <I>Synura</I> also diverges into two primary subclades, separating taxa with forward-projecting spines on the scale from those with a keel positioned on the scale proper. Approximately one third of the fossil species are extinct, whereas the remaining taxa are linked to modern congeners.</P><P>• <I>Conclusions:</I> The taxonomy of synurophytes, which relies extensively on the morphology of the siliceous components, is largely congruent with molecular analyses. Scales of extinct synurophytes were significantly larger than those of modern taxa and may have played a role in their demise. In contrast, many fossil species linked to modern lineages were smaller in the middle Eocene, possibly reflecting growth in the greenhouse climatic state that characterized this geologic interval.</P>

STUDIES ON ULTRASTRUCTURE AND THREE‐GENE PHYLOGENY OF THE GENUS <i>MALLOMONAS</i> (SYNUROPHYCEAE)

Jo, Bok Yeon,Shin, Woongghi,Boo, Sung Min,Kim, Han Soon,Siver, Peter A. Blackwell Publishing Ltd 2011 Journal of phycology Vol.47 No.2

<P>The genus <I>Mallomonas</I>, a common and often abundant member of the planktic community in many freshwater habitats worldwide, consists of 180 species divided into 19 sections and 23 series. Classification of species is based largely on ultrastructural characteristics of the siliceous scales and bristles that collectively form a highly organized covering over the cell. However, the relative importance of the different siliceous features of the scales, such as the dome, V rib, and secondary structures, as well as the different types of scales, in understanding the evolution and phylogeny of the genus is little known. In this study, we investigated the scale and bristle ultrastructure, along with sequences of three genes, for 19 isolates (18 species) of <I>Mallomonas</I> (18 isolates were from Korean habitats). The isolates represented nine of the 19 sections. Sequences for both the nuclear SSU and LSU rDNA and plastid LSU of RUBISCO (<I>rbc</I>L) genes for each of the 19 <I>Mallomonas</I> isolates and four outgroups were determined. Bayesian and maximum‐likelihood (ML) analyses of the data revealed that <I>Mallomonas</I> consists of two strongly supported clades. <I>Mallomonas bangladeshica</I> (E. Takah. et T. Hayak.) Siver et A. P. Wolfe was at the base of the first clade that included taxa from the sections <I>Planae</I> and <I>Heterospinae</I>, both of which lack a V rib on the shield of the scales. Our results indicated that the sections <I>Planae</I> and <I>Heterospinae</I> should be combined. The second clade, with <I>Mallomonas insignis</I> Penard and <I>Mallomonas punctifera</I> Korshikov at the base, contained taxa from the sections <I>Mallomonas, Striatae, Akrokomae, Annulatae, Torquatae, Punctiferae</I>, and <I>Insignes</I>, all of which have V ribs or well‐developed marginal ribs on the scales. Sister relationships between <I>Mallomonas</I> and <I>Striatae</I> were strongly supported, but interrelations among the remaining sections were not resolved, probably due to inclusion of too few species. Our results suggest that the current classification of the genus <I>Mallomonas</I> at the section level will require some revision. Additional species will need to be added in future analyses.</P>

<i>Mallomonas bronchartiana</i> Compère Revisited: Two New Species Described from Asia

Gusev, Evgeniy S.,Siver, Peter A.,Shin, Woongghi BioOne (Association des Amis des Cryptogames) 2017 Cryptogamie. Algologie Vol.38 No.1

Multigene phylogeny of <i>Synura</i> (Synurophyceae) and descriptions of four new species based on morphological and DNA evidence

Jo, Bok Yeon,Kim, Jong Im,Š,kaloud, Pavel,Siver, Peter A.,Shin, Woongghi Informa UK (TaylorFrancis) 2016 European journal of phycology Vol.51 No.4

<P>We used phylogenetic analyses based on multiple gene sequences (partial nr SSU and LSU rDNA, partial pt LSU rDNA, psaA and rbcL) from 148 strains (including three outgroups) and scale ultrastructure to examine phylogenetic relationships among species of the colonial genera Synura and Tessellaria. The phylogenetic tree based on the combined dataset was congruent with ultrastructural characteristics of the scales. Synura was divided into three major clades, two including species in section Synura, and one representing section Peterseniae. One clade, consisting of seven strains of S. uvella (section Synura), diverged at the base of the genus. The second clade consisted of the remaining species belonging to the section Synura. The third clade, containing organisms in the section Peterseniae and characterized by scales possessing a keel, was monophyletic with strong support values. Based on our findings, S. uvella needs to be in a separate section from other spine-bearing species, and we therefore propose new sectional ranks; Synura, Peterseniae, Curtispinae (presence of body scales with slender spines, tubular scales and caudal scales). We further propose four new species based on phylogenetic analyses and unique scale characters: S. longitubularis sp. nov., S. sungminbooi sp. nov., S. soroconopea sp. nov. and S. lanceolata sp. nov. Lastly, we propose a new genus name, Neotessella, to replace the invalid use of the name Tessellaria.</P>

Complex phylogeographic patterns in the freshwater alga <i>Synura</i> provide new insights into ubiquity vs. endemism in microbial eukaryotes

BOO, SUNG MIN,KIM, HAN SOON,SHIN, WOONGGHI,BOO, GA HUN,CHO, SUNG MI,JO, BOK YEON,KIM, JEE-HWAN,KIM, JIN HEE,YANG, EUN CHAN,SIVER, PETER A.,WOLFE, ALEXANDER P.,BHATTACHARYA, DEBASHISH,ANDERSEN, ROBERT Blackwell Publishing Ltd 2010 Molecular ecology Vol.19 No.19

<P>Abstract</P><P>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 <I>Synura petersenii sensu lato</I>. Our results suggest that this <I>Synura</I> 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 <I>Synura</I> is considerably older than currently proposed. The availability of tectonically relevant geological time (10<SUP>7</SUP>–10<SUP>8</SUP> 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.</P>