Evolutionary Implications of Meiotic Chromosome Behavior, Reproductive Biology, and Hybridization in 6X and 9X Cytotypes of Andropogon gerardii (Poaceae)

Authors

Guillermo A. Norrmann, Universidad Nacional de Nordeste
Camilo L. Quarín, Universidad Nacional de Nordeste
Kathleen H. Keeler, University of Nebraska - LincolnFollow

Date of this Version

1997

Citation

American Journal of Botany (1997) 84(2).

Comments

Copyright 1997, Botanical Society of America. Used by permission.

Abstract

Andropogon gerardii, big bluestem, has 60 and 90 chromosome cytotypes. Meiosis in the hexaploid was shown to be regular, although some secondary associations of bivalents form. Meiosis in the enneaploid (2n = 9x = 90) is irregular, leading to most gametes having unbalanced chromosome complements. Both cytotypes show considerable self-incompatibility. Cytotypes crossed freely, forming a variety of fertile euploids and aneuploids. Indistinguishable exomorphology, intermixing in natural populations, and compatibility suggest that A. gerardii is best understood as a cytotypically complex single species.