Molecular evidence for a natural hybrid between Isolepis crassiuscula and Isolepis lenticularis (Cyperaceae) in New Zealand

• Published in: New Zealand journal of botany Vol. 54; no. 4; pp. 433 - 445
• Main Authors: Yano, O, Tanaka, N, Ito, Y
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 01.10.2016; Taylor & Francis Ltd
• Subjects: Aquatic plants; Australasia; chloroplast DNA; Cyperaceae; hybridisation; internal transcribed spacer; Isolepis; New Zealand; PSE, New Zealand; Africa
• ISSN: 0028-825X; 1175-8643
• DOI: 10.1080/0028825X.2016.1205106

Isolepis R.Br. (Cyperaceae) is a genus of aquatic, wetland, or ephemeral sedges that comprises 76 species, mostly in the southern hemisphere, especially Africa and Australasia. Isolepis crassiuscula Hook.f., Isolepis lenticularis R.Br. and Isolepis producta (C.B. Clarke) K.L.Wilson are among the Australasian members of a morphologically well-defined subgenus Fluitantes. Specimens belonging to this subgenus, collected from Mount Tongariro, New Zealand, showed ambiguous yet somewhat intermediate morphology compared with these three species. We sequenced directly, or cloned and sequenced, nuclear DNA (nrITS) and chloroplast DNA (rbcL, rps16 and trnL) regions of these collections and samples of the three aforementioned species of subgenus Fluitantes. Ribotypes and chloroplast haplotypes were compared to resolve if the Tongariro collection was of hybrid origin and, if so, to address which of the three species may have been involved in the hybridisation event. The Tongariro plants had the species-specific ribotypes of I. crassiuscula and I. lenticularis and the chloroplast haplotype of I. lenticularis, strongly suggesting hybrid origin between them. No data support the inclusion of I. producta as a parent. The morphologically uniform population from which the Tongariro plants were collected is likely to be derived from a single hybridisation event, although this hypothesis merits further investigation.