In situ and Ex situ Conservation of Commercial Tropical Trees - ITTO

A Study of Genetic Variation Using AFLP Techniquein Populations of Kandelia candel in Ryukyu Islandsand Southern Japan325KO HARADA AND TAKANORI AZECHIDepartment of Forest Resources, Faculty of Agriculture, Ehime University3-5-7 Tarumi, Matsuyama, 790-8566 Japankharada@agr.ehime-u.ac.jpAbstract. To examine the extent of genetic variation within and among populations of Kandeliacandel, AFLP analysis was applied to 7 populations from the Ryukyu Islands and SouthernJapan. A total of 553 bands were detected using 4 selective primer pairs. The proportion ofpolymorphic loci and the average heterozygosity for each population ranged from 29.8 to58.2%, and from 0.067 to 0.152, respectively. Mean average heterozygosity (H) and nucleotidediversity (π) are 0.099 and 0.0098, respectively. The nucleotide diversity shown here is in therange of 52 to 80% of the values shown in that of the moderate temperate forests of Japanesebeech (Fagus crenata) and Japanese oak (Quercus mongolica var. grosseserrata); however, thefixation index (G ST) was shown to be 0.151, larger than the value shown in oak (0.083), andindicating considerable genetic differentiation among populations. The Iriomote-jima populationshowed the largest variation in both H and π. The UPGMA tree was constructed based onnucleotide diversities and showed no association with geographic distance. This result suggeststhat gene flow rate by seed migration is not simply correlated with the geographic distancebetween islands. The Kiire population is possibly a man-made population.IntroductionSpecies are composed of genetically diverse individuals; that is to say, geneticvariation has been accumulated in populations. It has been said that geneticvariation is the source of adaptive evolution in a changing environment and it isthus important for a population to maintain its adaptive and evolutionary potential(Newton et al. 1999). The extent of genetic variation depends on the length oftime the population has been established, the population size, and the mutationrate. Subdivided populations have been processed by both random genetic driftand natural selection to adapt to different environments. They have thenaccumulated genetic variation in different combinations of alleles and havebecome genetically diversified. These processes have been studied by usingelectrophoresis to detect protein polymorphism since the experiments of Lewontinand Hubby (1968) in Drosophila and Harris in humans (1966). Recently,however, a method called PCR has been more commonly used for these studiesto detect genetic variation at the DNA level. Variations at the DNA level, such