ALLOZYME DIVERSITY AND GENETIC IDENTITY IN SCHIEDEA AND ALSINIDENDRON(CARYOPHYLLACEAE, ALSINOIDEAE) IN THE HAWAIIAN-ISLANDS

Genetic diversity of allozymes, genetic identity based on allozyme var iability, and phylogenetic relationships were studied with respect to breeding system diversity, population size, and island age in 20 of th e 29 species of Schiedea and Alsinidendron (Caryophyllaceae: Alsinoide ae), a monophyletic lineage endemic to the Hawaiian Islands. Average l evels of genetic variability in Schiedea and Alsinidendron were compar able to or higher than those found in other Hawaiian lineages for whic h equivalent data are available [Bidens, Tetramolopium, and the silver sword alliance (Asteraceae: Madiinae)] and similar to average values f or species of dicots. Allozyme variability was strongly dependent on b reeding system, which varies widely in the Hawaiian Alsinoideae. Speci es with autogamous breeding systems showed very low variability, measu red as the number of alleles per locus, percent polymorphic loci, and mean heterozygosity per locus. Outcrossing hermaphroditic and dimorphi c species (those with gynodioecious, sub-dioecious, and dioecious bree ding systems) showed significantly higher genetic variability. Small p opulation size was associated with lower values for all measures of ge netic variability. Nearly half of the species occurring in small popul ations are also autogamous; thus, both factors may have influenced lev els of genetic variability in these species. Founder effect was appare nt in one species (Schiedea adamantis), which occurs in a single large population, has a gynodioecious breeding system but a very low geneti c variability. Island age appeared to have little effect on genetic va riability. Slightly lower values of genetic variability for species oc curring on Kaua'i and O'ahu result primarily from the occurrence of au togamous Alsinidendron species on those islands. Values for Nei's gene tic identity for different species pairs were 0.201-0.942, a far great er range than in Bidens, the silversword alliance, and Tetramolopium. Using UPGMA clustering, there was only moderate support for relationsh ips detected through cladistic analysis. Nei's unbiased genetic identi ty (I) was greatest among species with outcrossing breeding systems, w hich for the most part clustered together. Nei's genetic identities fo r self-fertilizing species were low, indicating that these species are less similar to one another and to outcrossing species, regardless of their affinities based on cladistic analysis. Parsimony analysis of a llele frequency data supported two clades also found in phylogenetic a nalyses using morphological and molecular data. Clades recognized in p arsimony analysis of allele frequencies were those lineages containing selfing species, indicating that conditions favoring fixation of alle les occurred in ancestral species. In contrast, maintenance of high ge netic diversity in outcrossing species interferes with recognition of phylogenetic relationships using allozyme variability.