Evolutionary distinctiveness and conservation priority of the endangered Najas ancistrocarpa (Hydrocharitaceae)

Abstract

Phylogeny is vitally important to evaluate evolutionary distinctiveness and conservation priorities of species. Najas ancistrocarpa is one of the rarest and least known East Asian species of the c. 30–40 species of the aquatic plant genus Najas (Hydrocharitaceae). We used a recently discovered collection of this nationally and regionally endangered species in Japan and East Asia to assess whether N. ancistrocarpa is a distinct species or an untypical form of other Najas species and to evaluate its conservation priority in a phylogenetic context. The sample set of our previous study, exploring worldwide phylogeny of the genus was used with N. ancistrocarpa to delimit species boundaries in Najas and obtain conservation priority scores, calculated by multiplying evolutionary distinctiveness and global extinction risks converted from Red List categories. We performed molecular phylogenetic analyses of plastid (ptDNA) and nuclear (ITS) DNA datasets, STACEY species delimitation analysis using the multilocus dataset and a measurement of conservation priority with Tuatara. Najas ancistrocarpa was consistently placed in ptDNA and ITS trees. Species delimitation analysis objectively assessed that N. ancistrocarpa is phylogenetically distinct. Phylogenetic conservation prioritization ranked N. ancistrocarpa the second highest priority species of the genus Najas. Overall, in terms of biodiversity conservation, N. ancistrocarpa represents an important Najas species in Japan and probably the world.

Key words:

• aquatic plants
• Bayesian
• biodiversity conservation
• East Asia
• molecular phylogeny
• species delimitation

Acknowledgements

The authors thank A. Barfod (AAU), R. Vogt (B), P. Stoffelen (BR), G. L. Robledo (Córdoba), C. Nepi (FI), H. Nagamasu (KYO), C. Gallagher, P. Milne (MEL), B. Summerell (NSW), and E. Vitek (W) for arranging loans from their institutions and/or for hospitality during the first author's recent visits; S. Fujii, T. Yamanouchi (MBK), J. Hansen (Stockholm), R. Pooma (BKF), H. Na (Seoul), K. Shuto (Fukushima), S.R. Yadav (Shivaji), J. Murata, H. Murata (Osaka), and Nb. Tanaka (TNS) for assistance in the field; C. Ishii (Tsukuba) for help with DNA sequencing; T. Ohi-Toma (TI) for technical advice. We would also like to thank I. Larridon (K), L. Bidgood, A. Hope, L. Jones and N. de Vere (NBGW) and R. Kaul (NEB) for English language review. This work was supported by Chinese Academy of Sciences (CAS) President's International Fellowship Initiative (PIFI) under Grant No. 2015PB022 to YI and National Museum of Nature and Science, Tokyo under the project ‘Integrated analysis of natural history collections for conservation of highly endangered species’ to NT.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed here: https://doi.org/10.1080/14772000.2017.1358219.

Additional information

Funding

This work was supported by Chinese Academy of Sciences (CAS) [grant number 2015PB022].