期刊
TAXON
卷 69, 期 1, 页码 124-141出版社
WILEY
DOI: 10.1002/tax.12205
关键词
ancestral state reconstruction; cytogenetics; heterochromatin; phylogeny; rDNA
资金
- Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET, Argentina)
- Agencia Nacional de Promocion Cientifica y Tecnologica (FONCyT)
- SECyT (Universidad Nacional de Cordoba, Argentina)
- FCEFN (Universidad Nacional de Cordoba, Argentina)
Lycium is the only member of tribe Lycieae (Solanoideae, Solanaceae), and it has a cosmopolitan distribution with its greatest diversity in southern South America, southern Africa, and southwestern North America. To date, there has been no attempt to synthesize and evaluate the significance of the available cytogenetical data from a phylogenetic perspective, which is the objective of this study. Firstly, new data on 27 taxa from all its range of distribution (FISH in all of them, banding in 23, Feulgen technique in 14) were provided to fill gaps in the information. The chromosome numbers of L. australe, L. humile, and L. repens were recorded for the first time. Species showed x = 12 with different ploidy levels (mostly diploid or tetraploid), small chromosomes, and symmetrical karyotypes. Lycium fremontii and L. repens were outstanding for having the highest numbers reported for the genus: 10x and 11x, respectively. North American species showed comparatively longer chromosomes. Secondly, cytogenetical traits were mapped on a phylogenetic tree, using character mapping and ancestral states reconstruction, to understand the dynamics of the evolutionary changes. The main cytotaxonomical features were included: chromosome number, presence of polyploidy, total length of the haploid chromosome set, mean chromosome length, karyotype formula, A(1) and A(2) asymmetry indices, percentage of heterochromatin, number of CMA(+)/DAPI(-) NORs bands, and number and position of 5S and 18S-5.8S-26S sites. The mean chromosome length, total haploid chromosome length, number of 18S-5.8S-26S loci, number of CMA(+)/DAPI(-) NORs bands underwent comparatively few transitions compared with the ploidy level and number of 5S loci. The mapping of the characters on the phylogenetic tree showed that the most probable ancestral chromosome number was 2n = 24 with several independent polyploidization events and one pair of each rDNA locus. The most likely ancestral condition for the genus would be: diploid, with small chromosomes, scarce heterochromatin, asynteny of rDNA loci, and one pair of both 18S-5.8S-26S and 5S loci.
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