Variation of nuclear DNA content in the biflorus species of Lonchocarpus (Leguminosae)

This represents the first study of nuclear DNA content in a large sample (1 35 spp.) From a tropical arboreal genus, in which a large proportion of the species were examined (42 spp., 31.1 %). Somatic chromosome numbers and 4C -DNA values for 51 taxa of Lonchocarpus are reported. All taxa were diploid with 2n = 22, but their DNA content ranged from 1.92 to 2.86 pg 4C nucleus , corresponding to a 48.95 % variation in genome size. Tn the 74 collection s studied, no correlation was observed between DNA content and habitat alti tude. Variation in nuclear DNA content was analysed at the level of genus, subgenus, section and subsection. Variation in genome size was also studied within some species, either among widely separated populations or among di fferent intraspecific taxa. Very little variation in genome size was detect ed between populations, subspecies. and varieties of the same species. The taxonomic implications of variation in nuclear DNA content are discussed. ( C) 2000 Annals of Botany Company.