Department of Biological Sciences, Aarhus University, Arhus C, Denmark.
BMC Genet. 2010 Jun 18;11:52. doi: 10.1186/1471-2156-11-52.
Elodea canadensis, Egeria densa and Lagarosiphon major are dioecious clonal species which are invasive in New Zealand and other regions. Unlike many other invasive species, the genetic variation in New Zealand is very limited. Clonal reproduction is often considered an evolutionary dead end, even though a certain amount of genetic divergence may arise due to somatic mutations. The successful growth and establishment of invasive clonal species may be explained not by adaptability but by pre-existing ecological traits that prove advantageous in the new environment. We studied the genetic diversity and population structure in the North Island of New Zealand using AFLPs and related the findings to the number of introductions and the evolution that has occurred in the introduced area.
Low levels of genetic diversity were found in all three species and appeared to be due to highly homogeneous founding gene pools. Elodea canadensis was introduced in 1868, and its populations showed more genetic structure than those of the more recently introduced of E. densa (1946) and L. major (1950). Elodea canadensis and L. major, however, had similar phylogeographic patterns, in spite of the difference in time since introduction.
The presence of a certain level of geographically correlated genetic structure in the absence of sexual reproduction, and in spite of random human dispersal of vegetative propagules, can be reasonably attributed to post-dispersal somatic mutations. Direct evidence of such evolutionary events is, however, still insufficient.
水蕴草、伊乐藻和大漂都是雌雄异株的克隆物种，它们在新西兰和其他地区具有入侵性。与许多其他入侵物种不同，新西兰的遗传变异非常有限。克隆繁殖通常被认为是进化的死胡同，尽管由于体细胞突变可能会产生一定程度的遗传分化。入侵克隆物种的成功生长和建立可能不是由于适应性，而是由于在新环境中证明有利的预先存在的生态特征。我们使用 AFLPs 研究了新西兰北岛的遗传多样性和种群结构，并将这些发现与引入的数量和引入区域的进化相关联。
在所有三个物种中都发现了低水平的遗传多样性，这似乎是由于高度同质的创始基因库造成的。水蕴草于 1868 年引入，其种群的遗传结构比 1946 年引入的伊乐藻和 1950 年引入的大漂更为复杂。然而，尽管引入时间不同，水蕴草和大漂具有相似的系统地理学模式。
在没有有性繁殖的情况下，存在一定程度的地理相关遗传结构，并且尽管有营养繁殖体的随机人为传播，这可以合理归因于散布后的体细胞突变。然而，这种进化事件的直接证据仍然不足。
