دانلود رایگان مقاله رانش واگرایی ژنتیکی قابل توجه زیستگاه پراکنده در گیاه بومی چینی

Abstract

Urophysa henryi (Oliv.) Ulbr., endemic to China with small populations, is known as a medicinal plant. In this study, ISSR markers were used to assess the genetic diversity and population structure throughout its entire distribution areas. Twelve primers revealed high genetic diversity at the species level (PPB ¼ 95.6%; H ¼ 0.3441; I ¼ 0.5111), as well as high level of genetic differentiation (FST ¼ 0.659, p < 0.001; GST ¼ 0.677) and restricted gene flow (Nm ¼ 0.239) among populations. According to the UPGMA and PCoA analysis, the 9 populations were clustered into three main groups, which were roughly in accordance with their geographical regions. In addition, a significant correlation between the genetic difference and geographic distances among populations was detected from the IBD analysis (r ¼ 0.516, p ¼ 0.003). These results indicated that the habitat heterogeneity and physical barriers play important roles in the modern distribution pattern and population divergence of U. henryi. However, human activities have posed serious threat to its living environment and continued survival. It is necessary to adopt some measures to restrict anthropogenic disturbances and preserve the existing populations.

4.3. Considerations for the conservation of U. henryi

Maintenance of genetic diversity and habitat integrity is important for long-term survival of a species or population (Frankel and Soule, 1981
). For U. henryi, genetic diversity within population was very low, along with the number of population is limited and individuals in each population are very small, which may be vulnerable to genetic drift or completeness loss and finally lead to species more susceptible to habitat deterioration. Additionally, small fragmented populations are sensitive to inbreeding, which may reduce heterozygosity and fitness-related genetic variation (Reed and Frankham, 2003). Worse, as a traditional Chinese medicinal plant, the habitats of U. henryi have been severely damaged by the human activities. In the past decades, many dams and tourism scenic spots have been built in areas where the wild populations of U. henryi are located in, which have caused serious damage to its natural habitats and inevitably increased the risk of extinction. Therefore, some relevant protective measures should be carried out. On the one hand, the maintenance of the existing populations and the avoidance of human disturbance are priority requisites. On the other hand, more energy should be focused on artificial cultivation (such as seed germination, plant tissue culture) to keep different genotypes and to increase molecular variance and fitness of individuals in the future.