Biogeography and origin of Lilium longiflorum and L-formosanum (Liliaceae)endemic to the Ryukyu Archipelago and Taiwan as determined by allozyme diversity

Allozyme diversity on 13 isozyme loci was investigated for two bulbous spec ies, Lilium longiflorum and L. formosanum, endemic to the subtropical archi pelago of continental origin located in East Asia. Degrees of allozyme vari ability and divergence for L. longiflorum were very high for insular endemi c species, indicating relatively longtime persistence of the present widesp read distribution across many islands in this phenotypically little-changed species. Lilium formosanum exhibited rather lower variability and divergen ce than did L. longiflorum and was genetically close to the southern periph eral populations of L. longiflorum with 0.978 as its highest generic identi ty value. Combined with other biological and insular geohistorical informat ion, our results suggest that L. longiflorum was established around the end of the Pliocene when the current distribution area was still a continuous part of the ancient Asian continent, and L. formosanum was derived fr-om so uthern populations of L. longiflorum around the late Pleistocene when the m ainland of Taiwan was completely separated from the adjacent islands and th e main continent. Depauperization of allozyme variability in some L. longif lorum populations was found on islands with lower altitudes. This reflects bottleneck effects after the complete or almost complete submergence of suc h low islands during the archipelago's development.