Systematic Evaluation of Isoëtes asiatica Makino (Isoëtaceae) based on AFLP, nrITS, and Chloroplast DNA Sequences
- 170 Downloads
On the basis of amplified fragment length polymorphism (AFLP) and nucleotide sequence data from nuclear ribosomal internal transcribed spacer (nrITS) and three chloroplast DNA regions (rbcL, cpITS, and trnS-psbC spacer), we investigated the species delimitation and the evolutionary lineage of Isoëtes asiatica from Hokkaido, Japan. The neighbor-joining (NJ) dendrogram based on AFLP markers revealed the well-defined clusters (bootstrap value = 100%) of I. asiatica. Results from the principal component analysis are largely congruent with those obtained in the NJ dendrogram. The maximum parsimony analysis, based on data from nrITS and three chloroplast DNA sequences, supported a monophyly of three species, I. asiatica, Isoëtes echinospora, and Isoëtes maritima from Hokkaido, Kamchatka, and Alaska regions. The distinct species status of I. asiatica was also well supported in the combined chloroplast DNA phylogeny. Therefore, I. asiatica appear to represent example of gradual speciation due to spatial isolation of ancestral populations followed by genetic divergence. Our results also suggest that I. asiatica is probably not the ancestral diploid of the polyploids occurring in East Asia.
KeywordsAFLP Chloroplast DNA Isoëtes I. asiatica Molecular phylogeny nrITS
The authors thank Dr. Edith Kapinos (KEW Botanical Garden, UK) for I. asiatica DNA sample from Kamchatka and Y. Ito (University of Tokyo) for collecting the plant materials of I. asiatica in Hokkaido, Japan. We also thank two anonymous reviewers for comments on the manuscript. This work was supported by grants from the Ministry of Environment as parts of the Eco-Technopia 21 project (KIEST 052-071-049) and in part by the Korea Research Foundation Grant (KRF-2009-0073766) to C. K.
- Hoot SB, Napier NS, Taylor WC (2006) Phylogeny and biogeography of Isoëtes (Isoëtaceae) based on nuclear and chloroplast DNA sequence data. Syst Bot 31:449–460Google Scholar
- Kott LS, Britton DM (1980) Chromosome numbers for Isoëtes in northeastern North America. Can J Bot 58:980–984Google Scholar
- Kuvaev VB (1993) The altitudinal distribution of vascular plants in the mountains of the Kronotskiy reservation (eastern Kamchatka). Botanicheskii Zhurnal 78:25–48Google Scholar
- Makino T (1904) Observations on the flora of Japan. Bot Mag Tokyo 18:129–131Google Scholar
- Makino T (1914) Observations on the flora of Japan. Bot Mag Tokyo 28:174–186Google Scholar
- Swofford DL (2002) PAUP*: Phylogenetic Analysis Using Parsimony and Other Methods, ver. 4.02b10. Sinauer, SunderlandGoogle Scholar
- Takamiya M, Watanabe M, Ono K (1997) Biosystematic studies on the genus Isoëtes (Isoëtaceae) in Japan. IV. Morphology and anatomy of sporophytes, phytogeography and taxonomy. APG 48:89–122Google Scholar
- White TJ, Birns T, Lee S, Taylor J (1990) Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ, White TJ (eds) PCR protocols: a guide to methods and applications. Academic, San Diego, pp 315–322Google Scholar