大叶藻居群微卫星遗传多样性研究

采用4对微卫星引物对大叶藻的7个地理居群进行了遗传多样性与遗传结构分析。扩增148株大叶藻得到57个等位基因, 每个位点平均等位基因数为6, 大叶藻居群的平均期望杂合度(He)为0.687, 平均观测杂合度(Ho)为0.417。青岛湾居群的遗传多样性最高(A=7.750, AR=7.043), 俚岛居群最低(A=4.750, AR=4.543)。从F_st值来看, 7个大叶藻居群间属于中度分化。UPGMA系统发育树显示, 中国4个大叶藻居群聚类到一起, 其遗传分化可能是由于历史大海草场的遗留小片段居群产生, 而中国、韩国、日本和爱尔兰居群间的遗传分化则主要是由于地理隔离造成的。自由交配估计结果支持海草的东亚起源说。青岛湾居群遗传多样性较高, 可优先作为大叶藻移植修复的材料和基因库, 并进行重点保护。

GENETIC DIVERSITY IN POPULATIONS OF ZOSTER MARINA L. INFERRED FROM NUCLEAR SSR MARKERS

Seagrasses are angiosperms that are thought to have become adaptive to aquatic environment independently. The marine, monocotyledonous Zostera marina is a species of Zosteraceae using traditional classifications, which widely distributes from subtropical to subfrigid coastal oceans. seven natural populations of Z. marina (Lidao, Tian'ehu, Qingdao Bay, Dalian, Naepo, Tokyo Bay and Finavarra) were used in this study. To study the mechanism of the genetic diversity and population structure of the seven populations, microsatellite marker (SSR) analysis was done. A total of 57 alleles were identified in 148 individuals across the four microsatellite primers analyzed, with a mean value of 6 alleles per locus. The mean expected heterozygosity (He) and observed heterozygosity (Ho) across all populations were 0.687 and 0.417, respectively, and a higher level of diversity was found in the population from the Qingdao Bay (A=7.750, AR=7.043) than other populations. The minimum F_st value was 0.051 between the populations from the Qingdao Bay and Dalian. The maximum F_st value was 0.261 between the populations from Tian'ehu and Finavarra. The F_st values suggested moderate genetic differentiation within most of the Z. marina populations. From the UPGMA tree, four populations in China (Lidao, Tian'ehu, Qingdao Bay and Dalian) clustered together, and the genetic relationships may be attributed to eelgrass meadow fragmentation. The geographic distance was responsible for the genetic differentiation from large-scale among populations in China (Lidao, Tian'ehu, Qingdao Bay and Dalian), Korea (Naepo), Japan (Tokyo Bay) and Ireland (Finavarra). Results of possible number of clusters supported that this seagrass species originated from East Asia. The population from the Qingdao Bay has higher genetic diversity, suggesting that populations in this region demand prioritized conservation and utilization for breeding programs.