Systematics of the tribe Stipeae (Gramineae) using molecular data

JACOBS, S.W.L.; BAYER, RANDALL; EVERETT, JOY; ARRIAGA, M.O.; BARKWORTH, M.E.; SABIN-BANDEREAU, ALEXANDRU; TORRES,M.A.; VAZQUEZ, FRANCISCO; BAGNALL, NEIL

Aliso

Rancho Santa Ana Botanic Graden

Lugar: Claremont, California, USA; Año: 2007 vol. 23 p. 349 - 361

0065-6275

Internal transcribed spacer (ITS) sequences have been determined for a wide range of stipoids grasses (Poaceae-Pooideae-Stipeae) Nardus was confirmed as the most appropiated outgroup. Anisopogon is consistently included among the stipoid genera. Lithachne and Oryza forma a clade and are clearly not close to Stipeae, and there is not support for including Brachyelytrum within Stipeae. Ampelodesmos and Diarrhena do appear among the core taxa insome analyses, but the possitions are unstabler and the evidence for retaining them is limited. So far there is inadequate support for rejecting them from Stipeae, so they should be included in any comprehensive study of the tribe. The ITS phylogeny supports a narrow interpretation of Jarava, one that includes only species with clear adaptation to anemophilous diaspore dispersal. There is no support for Achnatherum s.l. being a monophyletic group, nor are there any clear and consistent groups within it. Nassella, Hesperostipa and PIptochaetium, tremain well supposrted. The data suppost some internal grouping witih Nasella, but the sample size is small. It may be worthwhile investigating subgeneric relationships within Nassella. Anemanthele always appears asociated with, and sometimes within Austrostipa, but its position is inconsistent. We recommended continuing to recognize it at generic level because of its distinctive morphological characters. Stipa s.s. shows some cohesion, but the results also suggests that some species currently included in the genus do not belong in it, suggestions that are supported by other studies. There has been no advance in understanding Piptatherum. The data support some of the subgeneric groupings witin Austrostipa, but sugests that others should be conbined. Austrostipa subgen. Falcatae is well supposrted, in part by a shered deletion. Additional species of Stipa s.s. and Piptahterum are being sequenced to broaden the sampling of these two genera.