Genetic diversity of populations of the dioecious Myrsine coriacea (Primulaceae) in the Atlantic Forest

ABSTRACT Although a species’ sexual system may influence the genetic diversity of its populations in their natural environment, there have been few such studies involving indigenous species of the Atlantic Forest. Here we study Myrsine coriacea, a dioecious tree widely used in reforestation programs despite a lack of information about its natural interpopulation genetic variation. To address this knowledge gap, intra- and interpopulation genetic diversity were measured for male and female individuals of ten natural populations using ISSR markers. Greater intrapopulation genetic diversity indicated interpopulation gene flow, regardless of isolation and distance between populations. Multivariate analyses detected significant differences in genetic diversity between populations, but not between males and females, which indicates that genetic diversity did not differ between the two sex morphs. Distance between populations was unrelated to genetic diversity. Myrsine coriacea has not experienced a loss of genetic variability despite the characteristic segregated spatial distribution of its populations. These results suggest that obligatory cross-pollination and dispersal by birds may be important mechanisms for the maintenance of genetic diversity in natural populations of M. coriacea.

摘要 尽管物种的性系统可能会影响其自然种群的遗传多样性，但针对大西洋森林本土物种开展此类研究的案例仍较为匮乏。本研究以Myrsine coriacea为对象：该树种为雌雄异株乔木，尽管目前缺乏其自然种群间遗传变异的相关研究数据，却被广泛应用于造林工程中。为填补这一研究空白，我们采用简单序列重复区间标记（ISSR markers）技术，对10个自然种群的雌雄个体开展了种群内与种群间遗传多样性测定。研究结果显示，无论种群间的隔离程度与地理距离如何，种群内较高的遗传多样性水平均表明种群间存在基因交流。多变量分析结果表明，种群间的遗传多样性存在显著差异，但雌雄个体间并无显著区别，这说明两种性别形态的遗传多样性并无差异。种群间的地理距离与遗传多样性水平并无关联。尽管Myrsine coriacea的种群呈现典型的空间隔离分布特征，但其遗传多样性并未出现流失。上述结果表明，专性异花授粉与鸟类传播可能是维持Myrsine coriacea自然种群遗传多样性的重要机制。