New chromosomal data and karyological relationships in geranium: Basic number alterations, dysploidy, polyploidy, and karyotype asymmetry

Abstract

Chromosomal data and karyological relationships provides valuable contributions to understanding speciation and karyotypic phylogeny. Because of the large number of species, wide distribution, morphological differences and chromosomal variations, Geranium is an important genus for determining the relationship between chromosomal alterations and karyotypic phylogeny. In the present study, the chromosomal data of 38 taxa are provided, nine of which are given for the first time (G. eginense, G. gracile, G. ibericum subsp. jubatum, G. lasiopus, G. libani, G. libanoticum, G. petri-davisii, G. ponticum, G. psilostemon), five present new chromosome numbers (G. asphodeloides, G. ibericum subsp. ibericum, G. molle subsp. molle, G. pretense, G. rotundifolium), and 24 agree with previous reports. Eleven different diploid numbers (2n = 18, 20, 22, 26, 28, 30, 32, 46, 48, 64, and 84) are detected. In basic numbers, infraspecific variations are encountered. The comprehensive variations of basic numbers and the relatively low rate of polyploid species showed in the present study promote the evolutionary significance of karyotype alterations by dysploidy mechanism. Regarding karyological relationships, G. sanguineum forms a monophyletic group by quite different karyological features, which are different basic number, diploid number, and karyotype sample and high ploidy level. Other clad consists of two subclades with a medium strong monophyletic group. In regression analyses, there are significant positive correlations between THL and 2n/ploidy levels. Asymmetry indices (CVCL and M-CA) show weak positive correlations mainly caused by polyploidy. The most asymmetrical karyotypes are G. molle subsp. bruitium in intrachromosomal asymmetry and G. asphodeloides in interchromosomal asymmetry.