Tropical plant species have been the focus of considerable attention in regard to their potential economic and social importance in the face of rapidly diminishing biodiversity in the tropics. Pacific Island species represent an even more fragile resource because different island populations are widely scattered and overall population sizes are small. We examined the distribution of genetic variation in Campnosperma brevipetiolata (Anacardiaceae), an upland rainforest tree species that is of potential use for both lumber and reforestation efforts in the Federated States of Micronesia (FSM). Seeds were collected from multiple populations on four island groups in the Caroline Islands (Kosrae, Pohnpei, and Yap in the FSM; and the Republic of Palau) and subjected to an electrophoretic analysis involving four polymorphic genetic loci. We hypothesized that variation on these islands would decrease with increasing distance from the presumed Indo‐Malayan source of these island floras. Indeed, we found a trend of decreasing variation from west to east indicated by the mean number of alleles per locus (A = 1.50‐1.33), effective number of alleles per locus (Ae = 1.14‐1.12) and mean genetic diversity (He = 0.123‐0.107). We also found little genetic differentiation among the islands (Fpt = 0.174) and among subpopulations within islands (Fsp = 0.047), indicating that either there are high levels of gene flow among the islands by seed dispersal or that these populations have not been established long enough for divergence to have occurred. The lack of divergence among islands observed for Campnosperma brevipetiolata suggests that germplasm sampled from any one island population would be a suitable starting point for plant breeding or reforestation efforts.
The present study was conducted to assess the distribution of genetic variation within and among populations of Chamaecyparis thyoides in both marginal and centrally located populations. Allozyme frequency analyses of ten loci from foliage of four New Jersey populations and two North Carolina populations of C. thyoides showed polymorphic loci = 50%, mean number of alleles per locus = 2.8, effective number of alleles per locus = 1.17, and expected heterozygosity = 0.14. Diversity was highest in two populations from southern New Jersey. The isolated population at High Point, New Jersey had only two polymorphic loci and expected heterozygosity of 0.03. There was no correlation between genetic and geographic distances among populations, implying that cedar must have possessed some means of long-distance dispersal at the end of the last glacial period, rather than advancing northward step by step.
Tropical plant species have been the focus of considerable attention in regard to their potential economic and social importance in the face of rapidly diminishing biodiversity in the tropics. Pacific Island species represent an even more fragile resource because different island populations are widely scattered and overall population sizes are small. We examined the distribution of genetic variation in Campnosperma brevipetiolata (Anacardiaceae), an upland rainforest tree species that is of potential use for both lumber and reforestation efforts in the Federated States of Micronesia (FSM). Seeds were collected from multiple populations on four island groups in the Caroline Islands (Kosrae, Pohnpei, and Yap in the FSM; and the Republic of Palau) and subjected to an electrophoretic analysis involving four polymorphic genetic loci. We hypothesized that variation on these islands would decrease with increasing distance from the presumed Indo‐Malayan source of these island floras. Indeed, we found a trend of decreasing variation from west to east indicated by the mean number of alleles per locus (A = 1.50‐1.33), effective number of alleles per locus (Ae = 1.14‐1.12) and mean genetic diversity (He = 0.123‐0.107). We also found little genetic differentiation among the islands (Fpt = 0.174) and among subpopulations within islands (Fsp = 0.047), indicating that either there are high levels of gene flow among the islands by seed dispersal or that these populations have not been established long enough for divergence to have occurred. The lack of divergence among islands observed for Campnosperma brevipetiolata suggests that germplasm sampled from any one island population would be a suitable starting point for plant breeding or reforestation efforts.
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