The cultivars of Gracilaria lemaneiformis in Nanao (Guangdong province), Putian (Fujian) and Lianyungang (Jiangsu) all originate from the Qingdao (Shandong) wild population. After years of cultivation via vegetative propagation in marine farms in their new habitats, these cultivars vary in economic properties and morphological characters. In order to demonstrate whether the variations are caused by genetic variation or habitat shift, Gracilaria asiatica as an outgroup, the three cultivars, together with two morphologically different wild populations in Qingdao were characterized by RAPD markers and total soluble proteins. The results consistently showed that: (1) The Nanao cultivar, a selected strain enduring higher temperature, had the most variations. (2) The other two cultivars were closely related to one other. (3) The morphologically differentiated G. lemaneiformis populations in Qingdao were two separate populations. The results indicate that the use of RAPD markers is a powerful tool for exploring genetic relationships among G. lemaneiformis populations. Morphological and phenotypic variations of the cultivars are due to genetic changes rather than environmental changes. Years of artificial selection and asexual propagation have led to a reduction of intra-population genetic diversity in farmed populations and successive transplantation between farms has caused a reduction of inter-population genetic differentiation.
©2007 by Walter de Gruyter Berlin New York