Genetic variation and structure in six Rhododendron species (Ericaceae) with contrasting local distribution patterns in Hong Kong, China

Genetic variability of six rhododendrons with contrasting local distributio n patterns in Hong Kong was assessed by starch gel electrophoresis. Rhonode ndron championiae, R. hongkongense and R. simiarum are locally rare with di sjunct distributions, R. moulmainense is restricted and R. farrerae and R. simsii are common. For each species, 13-18 allozyme loci representing 12-16 enzyme systems were scored. The six species showed similar levels of genet ic variations (H-T ranged from 0.209 to 0.386 and A(T) ranged from 2.4 to 4 .1) which are high compared to plants with similar life history traits. Gen etic structure, in contrast, varied greatly between species, with F-ST rang ing from 0.056 to 0.393. The three rarest species had high genetic differen tiation (F-ST and F-PT) and distinct geographical patterns, while the other three had low differentiation and little or no geographical structure. The se differences are attributed to both present distributions and historical changes following deforestation within the last 1000 years. The conservatio n implications of these results are discussed.