Genetic distinctness and phylogenetic relationships among Undaria species (Laminariales, Phaeophyceae) based on mitochondrial cox3 gene sequences

Abstract

Genetic relationships among Undaria species and among populations of each species were studied based on DNA sequences of the mitochondrial cox3 gene. Although three Undaria species, U. peterseniana (Kjellman) Okamura, U. pinnatifida (Harvey) Suringar and U. undarioides (Yendo) Okamura, have been described based mostly on blade morphology, plants with intermediate morphologies have also been found. Multiple plants from several populations in Japan were collected. Morphological characters could identify most of the samples unambiguously. A few samples with intermediate morphologies were also collected. Mitochondrial haplotypes found in each population were different for each identified species, and each species had multiple haplotypes. In the cox3 haplotype network analysis, the numbers of steps between haplotypes within and between species were similar, and haplotypes of each species did not group together. The close genetic relationships among species strongly suggest that these species are conspecific. Alternatively, recent speciation could be possible with maintenance of ancestral polymorphisms within the species (i.e. incomplete lineage sorting). Haplotypes of samples with intermediate morphologies were different for each sample and the same as ones found in the local population, suggesting interspecific hybridizations among species.

TAXONOMIC REVISION OF SARGASSUM (FUCALES, PHAEOPHYCEAE) FROM FRENCH POLYNESIA BASED ON MORPHOLOGICAL AND MOLECULAR ANALYSES1

“…2005, Rohfritsch et al. 2007, Uwai et al. 2007) underlining their potential usefulness for the genus Sargassum .…”

A multi-locus time-calibrated phylogeny of the brown algae (Heterokonta, Ochrophyta, Phaeophyceae): Investigating the evolutionary nature of the “brown algal crown radiation”

“…To date, mitochondrial markers designed for phylogenetic purposes are scarce, and were mainly used at low taxonomic levels. For example, cox1 and cox3 were used to address species-level phylogenetic questions in kelp genera (Lane et al, 2007;Uwai et al, 2007). To our knowledge, only Lane et al (2006) and Bittner et al (2008) included mitochondrial markers in their data sets for phylogenetic studies within the orders Laminariales and Dictyotales.…”

The biogeography of kelps (Laminariales, Phaeophyceae): a global analysis with new insights from recent advances in molecular phylogenetics

“…Pseudolessonia laminarioides Saccharina angustata, bongardiana, cichorioides, coriacea, crassifolia, dentigera, groenlandica, gurjanovae, gyrata, japonica, kurilensis, latissima, longicruris, longipedalis, longissima, ochotensis, religiosa, sculpera, sessilis, yendoana (Lee 1998(Lee , 1999, as it has been demonstrated to be conspeciWc with Undaria pinnatiWda (Uwai et al 2007). I have, however, included Undariella kurilensis (described as a new genus independently from Lee [1998] by Kusakin 1997: see Selivanova et al 2007).…”

“…To my knowledge, there has been no deWnitive molecular taxonomic study on the possible conspeciWcity of these two taxa, although Baartsch et al (2008) cite the published abstract of Cho et al (2006) and are of the opinion that "there is much evidence … that S. longicruris is conspeciWc with S. latissima. There needs to be a consensus on how to deal with "incipient speciation" within genera: that is the existence of morphological forms with relatively slight diVerences within species, which have diVerent ecologies, and can be separated molecularly (Yotsukura et al 1999;Miller et al 2000;Erting et al 2004;Roberson and Coyer 2004;Lane et al 2007;Uwai et al 2007). As Lindstrom (2001) states: "more work is required to understand vicariance in seaweeds, especially in deciphering when a speciation event has occurred".…”