Objective To reveal the seed dispersal pattern and compare the genetic diversity differences among natural regeneration population (progeny population), maternal population and seedling plantation population of Casuarina equisetifolia, and to provide reference data for artificially promoting natural regeneration of C. equisetifolia seedling plantation.

Method Paternity analysis software Cervus 3.0 was used to determine the maternal parents of individuals in regeneration population, and to compare the genetic diversity of the three kinds of C. equisetifolia populations based on genotype data of progeny and candidate maternal parents obtained from 11 polymorphic SSR loci.

Result (1) Totally 137 alleles (N_a) were detected from 367 individual samples of maternal and progeny populations using 11 SSR markers, and the number of alleles per SSR locus varied from 6 to 24, with an average effective alleles (N_e) number of 4.95. The average expected heterozygosity (H_e), observed heterozygosity (H_o) and polymorphism information (PIC) were 0.75, 0.77 and 0.72 respectively. All the loci were categorized as moderate-high polymorphic loci. (2) At 80% confidence interval, the female parents of 148 progeny which accounted for 72.20% of the total progeny number were identified using genotype data obtained from 11 SSR markers. The seed effective dispersal distance of C. equisetifolia ranged from 10 m to130 m, with the mean dispersal distance of 71 m, which belongs to short-distance dispersal. The female parents were mainly concentrated in the northeast and east of the sampling plots, and their contribution to progeny reached up to 75.00%. (3) For the purpose of determining an even sample number, the genotype data of 84 individual samples were extracted respectively from the three populations for genetic diversity comparison. The results showed that the natural regeneration population presented slightly lower genetic diversity than the other two populations, but it still possessed relatively high genetic diversity based on its genetic parameters.

Conclusion The seed dispersal of C. equisetifolia is of a short-distance dispersal, and the natural regeneration population can also maintain a high genetic diversity, which provides reference data for artificially promoting the natural regeneration of the seedling plantation of C. equisetifolia in coastal shelterbelts of Southern China.