Phylogenetic analyses of <i>Zostera</i> species based on <i>rbcL</i> and <i>matK</i> nucleotide sequences: Implications for the origin and diversification of seagrasses in Japanese waters

Abstract

Seagrasses are composed of four families belonging to angiosperms and they are thought to become adaptive to aquatic life independently. Zosteraceae is one such family and because of the relatively high species diversity around Japan and Korea coast areas, the family might have arisen therefrom. To elucidate the origin and evolution of Zosteraceae which consists of three genera, Phyllospadix, Zostera , and Heterozostera, 2.8 kb nucleotide sequences of rbcL and matK genes in the chloroplast genome were examined for various species, including cosmopolitan Z. marina and endemic Z. caulescens . The phylogenetic analysis reveals the following three features. First, based on the synonymous nucleotide substitution rate of the rice chloroplast genome, we estimated the divergence times between Zosteraceae and its closest relative, Potamogetonaceae, and between different genera, Zostera and Phyllospadix, as approximately 100 million years (myr) and 36 myr, respectively, suggesting that Zosteraceae emerged somewhere in the period from 36 myr ago to 100 myr ago. Second, two subgenera of Zostera , Zostera and Zosterella , exhibit their reciprocal monophyly and appear to have differentiated from each other approximately 33 myr ago. However, the third genus Heterozostera branched off only 5 myr ago from the stem lineage leading to Zosterella and this seems too recent in comparison with the ancient divergence of the two subgenera. Third, we estimated the most recent common ancestor of subgenus Zostera as 6 myr. In Z. marina four haplotypes were found in the sample and have diversified in the past 1.5 myr. One haplotype is shared by both sides of the Japan Archipelago and its closely related haplotypes occur also in eastern Pacific Ocean. Based on these phylogeographic analyses, we propose a provisional age related classification of Zosteraceae to argue the origin and evolution.

An updated checklist of the vascular flora native to Italy

“…genera with the most represented number of cryptogenic and taxonomically doubtful taxa: c (≥2 taxa); t (≥5 taxa). Kato et al (2003). Nanozostera noltei (hornem.)…”

Seagrass Radiation after Messinian Salinity Crisis Reflected by Strong Genetic Structuring and Out-of-Africa Scenario (Ruppiaceae)

“…rbcL [27], mat K [28] or concatenated e.g. rbc L with trn L [29], rbc L with mat K [30] and combined cpDNA-nuclear DNA approach e.g. ITS 1, mat K, rbc L, psb A- trn H [31] but most have low resolving power for shallow phylogenies.…”

Development of a DNA Barcoding System for Seagrasses: Successful but Not Simple

“…They evolved independently at least three times between 75 and 17 million years ago [2]–[4]; hence, seagrasses form a paraphyletic group including four core families (Cymodoceaceae, Hydrocharitaceae, Posidoniaceae, and Zosteraceae). These marine plants cover large geographic ranges worldwide [5], surviving most diverse environmental conditions.…”