GENETIC DIVERSITY OF PHILIPPINE RUBUS-MOLUCCANUS L. (ROSACEAE) POPULATIONS EXAMINED WITH VNTR DNA PROBES

Two synthetic DNA probes composed of tandemly repeated 'core' sequence s (GACA and GATA) were us ed to examine ge ne tic diversity at multipl e variable-number-tandem-repeat (VNTR) loci within and among four spat ially isolated Philippine populations of Rubles moluccanus L. (Rosacea e), an uncultivated bramble widely distributed throughout southeast As ia-Malesia. Central goals were to determine whether apomictic propagat ion was detectable in R. moluccanus and to examine whether populations isolated on separate islands, or on mountain tops on a single island, were genetically differentiated. Sampling 22 individuals per populati on, the findings include: (1) no two individuals shared identical VNTR band profiles and thus apomictic propagation was not detected; (2) th e mean number of bands scored per individual was 24.3 (SD = 3.91) and the proportion of polymorphic loci within populations ranged from 0.69 to 1.00 (mean = 0.86 +/- SD = 0.085); (3) the average proportion of b ands shared between individuals within populations ranged from 0.39 to 0.67 (0.50 +/- 0.067), while average interpopulation similarity range d from 0.21 to 0.50 (0.32 +/- 0.092); and (4) estimated heterozygosity within populations ranged from 0.42 to 0.79 (0.62 +/- 0.083), while i nterpopulation heterozygosity ran from 0.62 to 0.81 (0.74 +/- 0.062). Permutation tests were used to estimate the statistical significance o f differences in similarity between populations. A Luzon population is olated by 1200 km was always significantly different in similarity tes ts when compared with each of the other three populations, all located on Mindanao (and separated by at least 100 km but less than 250 km). Of the latter three, only one population differed significantly from t he other two in the degree of VNTR markers shared, possibly reflecting biogeographic partitioning suggested for the island. Across all popul ations, average estimated Fst was 0.154, although mean inter-island Fs t (0.224) was significantly higher than mean intra-island Pst (0.085). These results suggest that, while intra-island gene flow is relativel y high, significant differentiation of tropical species may occur even over short distances on individual islands. Preservation of only a li mited number of populations may result in a significant loss of geneti c diversity in such species.