Apomixis:

Evolutionary theory proposes that interactions between host and pest species cause rapid evolution which favors sexual reproduction. These theories can be tested in some populations of B. holboellii, which are genetically polymorphic for sexual vs. apomictic (asexual) reproduction. Apomixis is found in interspecific hybrids, which may be diploid, aneuploid or polyploid. To better understand the birth and death process of asexual lineages, we have examined microsatellite genotypes within and among populations in the Northern Rocky Mountains. About 20% of these populations contain both sexual and asexual diploids. At these sites we seek to understand the ecological and evolutionary forces which influence this breeding system polymorphism.

Chromosome painting of an aneuploid hybrid between B. holboellii and B. stricta, showing chromosomes from B. holboellii in red, and chromosomes from B. stricta in green. From Schranz et al., New Phytol . 2006