MOLECULAR DELINEATION OF SPECIES AND SPECIES RELATIONSHIPS IN THE RED ALGAL AGAROPHYTES <i>GRACILARIOPSIS</i> AND <i>GRACILARIA</i> (GRACILARIALES)<sup>1</sup>

抄録

<jats:title>ABSTRACT</jats:title><jats:p>Delineation of species in the economically important agarophyte genera <jats:italic>Gracilaria</jats:italic> and <jats:italic>Gracilariopsis</jats:italic> has proven extremely difficult using available morphological characteristics. In this study, we examine the usefulness of two transcribed spacers for molecular systematic studies of these genera. The polymerase chain reaction was used to amplify the internal transcribed spacers (ITSs) and the intervening 5.8S ribosomal DNA of the nuclear ribosomal repeat region. In addition, a plastid spacer region and flanking regions of coding genes were amplified from the RUBISCO operon. Both regions were sequenced for individuals and populations of <jats:italic>Gracilariopsis lemaneiformis</jats:italic> (Bory) Dawson, Acleto, et Foldvik to determine the usefulness of these spacers in delimiting populations. These studies reveal that there is as much variation among individuals of a population as there is between individuals of geographically separate populations. In addition, the ITS spacer regions were compared between different species of <jats:italic>Gracilariopsis</jats:italic> and <jats:italic>Gracilaria.</jats:italic> The nuclear ITS spacer region is conserved at a species level in both genera and provides phylogenetically informative characters that can be used to examine species interrelationships among relatively closely related taxa. However, because of the difficulties of aligning this entire region among species from the two genera, the ITS region is not useful for examining intergenera relationships. ITS interspecies sequence comparisons indicate that <jats:italic>Gracilariopsis lemaneiformis</jats:italic> from California is significantly different from <jats:italic>G. lemaneiformis</jats:italic> from China and that a species of <jats:italic>Gracilariopsis</jats:italic> from Peru is more closely related to <jats:italic>G. lemaneiformis</jats:italic> from North Carolina than it is to the other <jats:italic>Gracilariopsis</jats:italic> species examined. In addition, these studies indicate that <jats:italic>Gracilaria chilensis</jats:italic> Bird, McLachlan, et Oliveira from New Zealand and <jats:italic>Gracilaria tenuistipitata</jats:italic> Chang et Xia from southeast Asia are as closely related as are <jats:italic>Gracilaria verrucosa</jats:italic> (Hudson) Papenfuss, <jats:italic>G. pacifica</jats:italic> Abbott, and <jats:italic>Gracilaria robusta</jats:italic> Kylin. Phylogenetic analysis of aligned plastid spacer sequences from <jats:italic>Gracilaria</jats:italic> and <jats:italic>Gracilariopsis</jats:italic> taxa provide similar conclusions about species relationships.</jats:p>

収録刊行物

被引用文献 (10)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ