Varying success of Spartina spp. invasions in China: Genetic diversity or differentiation?
An, Shuqing*,1, Wang, Zhongsheng 1, Yu, Donghai1, Guan, Yongjian1, Wang, Yunjing1, 1 School of Life Science, Nanjing 210093, Jiangsu, China
ABSTRACT- Biological invasions are threatening biodiversity and causing considerable economic loss to the invaded areas. However, little is known about why some of species become successful invaders. Some studies suggested that high genetic diversity contributed to the success of plant invasions, whereas others showed that reduced genetic variation could make invasive species more successful. Our extensive studies on Spartina showed that S. alterniflora with higher genetic differentiation (Fst) was more successful in invading coastal ecosystems than S. anglicawith low Fst, although the latter had much higher genetic diversity. Thus genetic differentiation may be more important than genetic diversity in determining invasion success. In this paper, amplified fragment length polymorphism (AFLP) markers were used to analyze the genetic variations within and among seven Spartina alterniflora and three S. anglica populations throughout coastal ecosystems in China. Our findings suggested in S. alterniflora, a high level of intraspecific genetic diversity at both population and species levels. Its populations maintained sufficiently high diversity level, suggesting a substantial outcrossing. There exited a relatively high level of genetic differentiation among populations. Adjacent populations shared high level of genetic identity. The level of gene flow was estimated to be 1.9556 individual per generation between its populations. In contrast, in S. anglica, a low level of intraspecific genetic diversity and differentiation among populations were detected. However, adjacent populations of S. anglica shared higher level of genetic identity than S. alterniflora. This was true for the level of gene flow of S. anglica. We conclude that differentiation of ecotypes in different microhabitats, high genetic diversity and considerable plasticity may facilitate widespread expansion of Spartina alterniflora.
Key words: S. anglica, gene flow, Spartina alterniflora, genetic diversity and differentiation
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