The genus Collinsia. IX. Speciation and chromosome repatterning
Cytologia 252: 233-243
ISSN/ISBN: 0011-4545 Accession: 025802477
Eleven species of Collinsia Nutt. were mated in about 44 different combinations. From these interspecific hybridizations data were obtained on yield of germinating seed, mean number of chiasmata at metaphase, heterozygous paracentric inversions and on the fertility of the hybrids. Many hybrids had one to two interchange complexes at metaphase I, involving four, six, eight or ten chromosomes. The basic chromosome number in the genus is 7, and the genomes of all 11 species appear to be homologous. One species, C. torreyi, however, has 21 bivalents at MI, and is considered to be an allohexaploid having 3 non-homologous genomes.' The fertility of sterility of certain interspecific combinations was correlated with the presence of chromosome abberations. It is suggested that chromosome repatterning has been the major factor in speciation in Collinsia, with polyploidy having a relatively minor role.