Widespread cytotypic variation, cytogeography and dynamic analysis of Lysimachia mauritiana (Primulaceae) on Takarajima Island in the Ryukyu Archipelago of Japan

摘要

Lysimachia mauritiana displayed a comprehensive karyotypic polymorphism (18 cytotypes) in the Ryukyu Archipelago of Japan. To explore chromosome variation on Takarajima Island, karyomorphological analysis was made in 238 individuals from six localities throughout the island. Total five different chromosome numbers (2 n =16, 17, 18, 19, 20) and 11 cytotypes were recognized in the area. In the localities of the island, multiple cytotypes coexisted and diversified every year among and within population, although populational coexistence of plural cytotypes was maintained. Especially, three cytotypes of 16 (6 m ), 17 (5 m ) and 18 (4 m ) co-occurred in every locality, indicating that they were involved in a formation of cytotypes in Takarajima Island.