J Syst Evol ›› 1995, Vol. 33 ›› Issue (5): 433-443.

• Research Articles • Previous Articles     Next Articles

Biosystematic Studies on Adenophora potaninii Korsh. Complex (Campanulaceae) III. Genetic Variation and Taxonomic Value of Morphological Characters

Ge Song, Hong De-yuan   

  • Published:1995-09-10

Abstract: Adenophora potaninii Korsh.complex is a morphologically variable group including six species.As shown in many species in the genus Adenophora,the variability of many morphological characters in the complex under investigation is amazingly great,which brings difficulties in the delimitation and indentification of taxa.In the present study,six populations representing five species in the complex were systematically sampled to investigate the pattern of morphological variation within population and to detect the genetic basis of the variation with progeny tests and controlled crosses.The results are as follows: Great morphological variation within population is found (Fig.1),including characters such as leaf shape,teeth number and size of leaf margins,teeth number of calyx lobes,and indumentum on the surface of stems and leaves,which were previously considered as diagnotic.Systematic sampling and statistical analysis show that the differences in the above characters exhibit continuous patterns of variation within population (Fig.1,2),though they are highly correlated (Table 2).From progeny testing and crossing between two contrast types of individuals (oblong,dentate and pubescent leaves vs.narrow,entire and glabrous leaves)it is evident that those characters show continuous variability in segregating progenies (Fig.3,4)and appear to be influenced by large numbers of loci with individually slight effects.Since most wild populations were highly heterozygous for those characters,the individuals in one extreme of variation can produce their variable offsprings including individuals similar to those in the other extreme (Fig. 3). This is also true for the indumentum density on stems and teeth number of calyx lobes. In this complex, A. biformifolia Y. Z. Zhao, A. bockiana Diels and A. polydentata P.F. Tu et G. J. Xu were described exclusively based on leaf shapes, teeth number of leaf margins and calyx lobes, teeth size of leaf margins, and indumentum on the surface of stemsand leaves. It is demonstrated, however, that the variation of those characters is of a quantitative nature and show no discontinuities. As a result, genetic analysis of diagnostic characters along with their sympatric distribution and same habitats, strongly suggest that A.biformifolia as well as A. bockiana and A. polydentata are actually the extreme individuals within A. wawreana and A. potaninii respectively and should not be recognized as taxa at any taxonomic level.

Key words: Adenophora potaninii complex, Genetic variation, Morphological characters, Classification