CYTOPHOTOMETRIC ESTIMATION OF INTERSPECIFIC AND INTRASPECIFIC VARIATION IN NUCLEAR-DNA CONTENT IN 10 TAXA OF THE GELIDIALES (RHODOPHYTA)

Cytofluorometric analysis of DAPI-stained nuclei was used to confirm changes in ploidy level associated with life-history stage and to estimate nuclear genome size in 10 taxa of the red algal order Gelidiales. Results indicate an alternation of haploid gametophyte with diploid sporophyte generations in the taxa where both life-history stages were available. Estimates of 2C genome size in the sporophyte generation range from 0.42 to 0.66 pg for all species investigated. ANOVA of sporophytic 2C DNA amounts shows that there was significant variation among taxa, and indicates that quantity of nuclear DNA may be useful as an exclusionary taxonomic criterion.