Geographic distribution and habitat differentiation in diploid and triploid Lilium lancifolium of South Korea

Habitats and geographic distribution were investigated for diploid and triploid L. lancifolium grown in islands and mainland areas covering a whole country of South Korea. Of 367 populations investigated, 185 (50.4%) and 182 (49.6%), respectively, were diploid and triploid populations. Diploid was intensively distributed only along western to southeastern coastal areas and islands, whereas triploid spread dominantly in inland areas of the Korean Peninsula. Diploid was specific to such seaside habitats as coastal cliffs or beaches but never to inland habitats. Triploid tended to prefer often-disturbed inland habitats such as roadsides, arable lands, hilly fields and riversides, though 23% of triploid individuals were growing in the coastal cliffs. The facts indicate that adaptability for disturbed habitats are crucial for the distribution range of each cytotype. Nonetheless, triploids were rarely found in coastal habitats within the diploid distribution range. Autotriploid formation from diploid ancestors under natural conditions may be suppressed by rareness of higher unreduced gamete productivity within the diploid species and/or by minority cytotype exclusion.