CLONAL DIVERSITY IN HIGH ARCTIC OSTRACODES

It remains unclear why the majority of parthenogenetic lineages persis t for only brief periods of evolutionary time. However, by characteriz ing their patterns of genetic variation, it is possible to gain insigh ts regarding their evolutionary origin and potential. We examined clon al diversity patterns in high arctic populations of freshwater ostraco des with the goal of clarifying the factors promoting genotypic divers ity. Allozyme electrophoresis showed that the three dominant ostracode species in high arctic ponds reproduce via apomictic parthenogenesis that two of these species (Prionocypris glacialis, Candona rectangulat a) were both highly clonally diverse, and had allozyme phenotypes sugg estive of polyploidy. Scanning microdensitometry confirmed that many c lones of P. glacialis at Igloolik were polyploid. In contrast to most other polyploids, clones of P. glacialis seem to be autopolyploids. Al though clonal variation in P. glacialis may reflect multiple transitio ns to parthenogenesis in an undetected sexual population, it seems lik ely that genomic recombination associated with polyploidy has also pla yed a role in generating local diversity following the transition to p arthenogenesis.