Morphological and genetic variation in the endangered Victorian endemic grass Agrostis adamsonii Vickery (Poaceae)

Abstract

Until 1987, Agrostis adamsonii Vickery was known only from a single collection made in 1853 and was thought to be extinct. Further populations have been located but conservation of the species is hampered by a lack of taxonomic and genetic information. Variation within and between species was assessed morphometrically and by random amplified polymorphic DNA (RAPD) analysis. RAPD analysis has confirmed that the separation of A. adamsonii from two other similar species on the basis of morphological characters has a genetic basis and enables identification of A. adamsonii in the absence of fertile material. RAPD analysis has also provided information on the genetic diversity within A. adamsonii. Agrostis adamsonii is confirmed as a well-supported species with all six populations studied showing a high degree of similarity to each other but with evidence of genetic differentiation. Genetic diversity is lower compared to the widespread A. avenacea J.F.Gmel., but significantly higher than in the more restricted A. billardierei R.Br., with a Shannon information index of 0.0147 (average over populations) compared to 0.0068 and 0.1389 for A. billardierei and A. avenacea, respectively. A very high level (82.1%) of RAPD diversity occurs among populations of A. adamsonii. Gene flow between populations appears highly restricted and will have implications for the management of extant populations.