Senecio L. (Asteraceae) in Australia: Nuclear DNA amounts

Abstract

Nuclear DNA amounts of 28 species of Senecio native to Australia and of four exotic species are reported. DNA amounts per 4C nucleus range from 4.22 pg to 42.90 pg, a 10-fold difference. Some of the variation is due to polyploidy as chromosome numbers range from n = 5 (by dysploid reduction) to n = 50, but DNA amounts per genome also vary from 0.84pg to 4.69 pg, a 6-fold difference. DNA amounts correlate with cell size and, in some instances, the size of structures. There is also a correlation between DNA amount and generation length which corresponds with previous observations. The possible direction of change in DNA amount and the influence of natural selection on this process are discussed.