Relationship between nuclear DNA content and speciation inAlysicarpus

摘要

4C nuclear DNA contents were determined in 11 collections ofAlysicarpusNeck, representing 9 species and 3 varieties. The 4C nuclear DNA contents varied from 9.225 to 13.194 picograms. A clustering of DNA values were observed in the species and varieties belonging to different sub-genera.A. belgumen-siswhich has a higher chromosome number of 2#xbb; = 22 showed the maximum DNA content as compared to the rest of the species and varieties which have chromosome number 2n= 16. Per-chromosome DNA amounts showed thatA. belgaumensishas more affinity to members of Microcalycinae. Observations on the DNA contents indicated that the sub-genusDesmodiastrummay have originated from a common ancestor as Microcalycinae and Macrocalycinae or from some species of Microcalycinae by aneuploidy without increase in per-chromosome DNA content. The development of Macrocalycinae seems to be associated with increase in perchromosome DNA content. This is in agreement with PRAIN'S classification of the genus as consisting of 3 sub-genera and members ofDesmodiastrumas belonging to the genusAlysicarpusrather thanDesmodium.