Patterns of Isozyme Variation in the Antennaria rosea (Asteraceae: Inuleae) Polyploid Agamic Complex

Abstract

Antennaria is a genus of dioecious, perennial herbs, which are distributed over much of North America and Eurasia. The A. rosea polyploid agamic complex occurs throughout western North America and is perhaps the most complicated, with respect to morphology and taxonomy, of all the Antennaria species complexes. The complex is composed of gametophytic apomicts and consequently the populations contain only pistillate clones. Morphological studies have demon- strated that the A. rosea complex is a compilospecies derived through hybridization from perhaps as many as eight, sexually reproducing species of Antennaria, with which it has a partially sympatric distribution. Enzyme electrophoresis was used both to assess the degree of divergence among 33 populations of A. rosea, as well as to determine the amount of divergence between A. rosea and its sexual progenitors. Gene statistics demonstrate that A. rosea contains more gene diversity than its amphimictic relatives. The electrophoretic data provide evidence, independent, yet supportive, of morphology, that A. corymbosa, A. microphylla, and A. umbrinella are among the sexual progenitors of some of the A. rosea segregates. Morphology also implicates A. aromatica, A. densifolia, A. marginata, A. media, A. racemosa, and A. rosulata in the parentage of A. rosea, although the electrophoretic data neither support nor contradict this hypothesis independent of morphology. The A. rosea complex is probably of recent origin because it has diverged only moderately from its sexual progenitors, having only one novel allele that does not occur in the amphimicts.