Origin and evolutionary history of freshwater Rhodophyta: further insights based on phylogenomic evidence

Abstract

Freshwater representatives of Rhodophyta were sampled and the complete chloroplast and mitochondrial genomes were determined. Characteristics of the chloroplast and mitochondrial genomes were analyzed and phylogenetic relationship of marine and freshwater Rhodophyta were reconstructed based on the organelle genomes. The freshwater member Compsopogon caeruleus was determined for the largest chloroplast genome among multicellular Rhodophyta up to now. Expansion and subsequent reduction of both the genome size and GC content were observed in the Rhodophyta except for the freshwater Compsopogon caeruleus. It was inferred that the freshwater members of Rhodophyta occurred through diverse origins based on evidence of genome size, GC-content, phylogenomic analysis and divergence time estimation. The freshwater species Compsopogon caeruleus and Hildenbrandia rivularis originated and evolved independently at the inland water, whereas the Bangia atropurpurea, Batrachospermum arcuatum and Thorea hispida are derived from the marine relatives. The typical freshwater representatives Thoreales and Batrachospermales are probably derived from the marine relative Palmaria palmata at approximately 415–484 MYA. The origin and evolutionary history of freshwater Rhodophyta needs to be testified with more organelle genome sequences and wider global sampling.

Organization of plastid genomes in the freshwater red algal order Batrachospermales (Rhodophyta)

“…These results strongly contradict the statements by Nan et al. () that Batrachospermales and Thoreales are derived from the marine relative Palmaria palmata (Palmariales) ~415–484 mya. We therefore advocate that the inclusion of more taxa in Nemaliophycidae is critical to properly approach the issue in terms of the evolutionary transition from marine to freshwater habitats in the freshwater lineages including Batrachospermales, Thoreales, and Balbianiales.…”

“…Yang et al (2016) showed these two orders as part of a large clade, with Batrachospermales diverging earlier (~330 mya) from a highly diverse group including the Thoreales and several orders including freshwater and marine representatives (e.g., Acrochaetiales, Balbianiales, and Nemaliales). These results strongly contradict the statements by Nan et al (2017) that Batrachospermales and Thoreales are derived from the marine relative Palmaria palmata (Palmariales) 415-484 mya. We therefore advocate that the inclusion of more taxa in Nemaliophycidae is critical to properly approach the issue in terms of the evolutionary transition from marine to freshwater habitats in the freshwater lineages including Batrachospermales, Thoreales, and Balbianiales.…”

“…The classical system with three families (Batrachospermaceae, Lemaneaceae, and Psilosiphonaceae; Cole 1982, Sheath et al 1996) was reduced to only one family (Batrachospermaceae) in a molecular phylogeny analysis based on two molecular markers 26 (Entwisle et al 2009). In contrast to some other Nemaliophycidae orders, data on cp genomes for members of the Batrachospermales are scarce and have been reported only in studies involving other red algal groups: Kumanoa americana (Lee et al 2016) and Sheathia arcuata (Nan et al 2017).…”

Complete mitochondrial genomes of six species of the freshwater red algal order Batrachospermales (Rhodophyta)

“…Although there are some comprehensive studies on mt genomes for some groups of red algae (e.g. Yang et al 2016;Salomaki and Lane 2016), only two mt genomes were described for members of Batrachospermales so far: Sheathia arcuata by Nan et al (2017) and Lympha mucosa by Wolf et al (2017). This contrasts with the eight plastid genomes described for species of the order (Lee et al 2016;Nan et al 2017;Paiano et al 2017).…”

Primer registro de Compsopogon caeruleus (Rhodophyta, Compsopogonales) en Córdoba (Argentina) y consideraciones sobre la presencia del género en Argentina

“…En Argentina son escasos los trabajos dedicados al estudio de este grupo de algas (Lazo, 1978;Gauna y Parodi, 2005;Daga, Soteras, Daniele, Dominguez, 2014), en especial las referidas a agua dulce. Usualmente, son componentes importantes de la ficoflora de ríos o arroyos, ya sea en términos de abundancia o distribución (Nan et al, 2017), tienen hábitos bentónicos y en comparación poseen menor tamaño que los miembros marinos (Sheath y Hambrook, 1990).…”