臺灣產天門冬科綿棗兒之核型研究

The karyotype of Barnardia japonica (Asparagaceae) in Taiwan

綿棗兒（Barnardia japonica（Thunberg）Schultes & J. H. Schultes）廣泛分布於東亞，其生長於各類型棲地，並以核型高度變異著稱。本研究分析此物種於北台灣各族群的核型。結果顯示，臺灣的綿棗兒具有三種不同的核型──AA型（2n＝2x＝16）、BB型（2n＝2x＝18）及AABB型（2n＝4x＝34），其中BB型為首次在臺記錄之核型。本研究未於任何族群中發現B染色體。根據核型的分布，二倍體族群與多倍體族群間存在一明顯的地理界線，顯示不同核型間存在棲地上的區隔。AABB型為最廣佈的核型，此核型分布於海濱區域。相較之下，二倍體族群僅發現於較內陸的丘陵。這些發現顯示多倍體化可能造成族群間的棲位分化。

Barnardia japonica (Thunberg) Schultes & J. H. Schultes grows in a wide range of habitats across East Asia and is known to have highly variable karyotypes. In this study, the karyotype of different populations from northern Taiwan was analyzed. Among the three karyotypes identified--abbreviated as AA (2n = 2x = 16), BB (2n = 2x = 18), and AABB (2n = 4x = 34)--BB was recorded for the first time in Taiwan. B chromosomes F and f were not found in all materials collected. The results suggested the presence of a clear geographic boundary between diploid and polyploid populations, and revealed that different karyotypic populations occupied different habitats. AABB was the most widespread karyotype as all populations of this type were observed in the island's coastal regions. In contrast, types AA and BB were present only on inland hills. These findings indicate the existence of niche differentiation by polyploidy.