IMBIV   05474
INSTITUTO MULTIDISCIPLINARIO DE BIOLOGIA VEGETAL
Unidad Ejecutora - UE
artículos
Título:
Using chromosomal data in the phylogenetic and molecular dating framework: Karyotype evolution and diversification in Nierembergia (Solanaceae) influenced by historical changes in sea level
Autor/es:
MOSCONE E. A.; COCUCCI A. A.; ACOSTA M. C.
Revista:
PLANT BIOLOGY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2016 vol. 18 p. 514 - 526
ISSN:
1435-8603
Resumen:
Karyotype data within a phylogenetic framework and molecular dating wereused to examine chromosome evolution in Nierembergiaand to infer how geological or climatic processes have influenced in thediversification of this solanaceous genus native to South America and Mexico. Despitethe numerous studies comparing karyotype features across species, including theuse of molecular phylogenies, to date relatively few studies have used formalcomparative methods to elucidate chromosomal evolution, especially to reconstructthe whole ancestral karyotypes. Here, we mapped on the Nierembergia phylogeny one complete set of chromosomal dataobtained by conventional staining, AgNOR-, C- and fluorescent chromosomebanding, and fluorescent in situhybridization. In addition, we used a Bayesian molecular relaxed clock toestimate divergence times between species. Nierembergiashowed two major divergent clades: a mountainous species group with symmetricalkaryotypes, large chromosomes, only one nucleolar organizing region (NOR), andwithout centromeric heterochromatin, and a lowland species group withasymmetrical karyotypes, small chromosomes, two chromosomes pairs with NORs andcentromeric heterochromatin bands. Molecular dating on the DNA phylogenyrevealed that both groups diverged during Late Miocene, when Atlantic marineingressions called the ?Paranense Sea? probably forced the ancestors of thesespecies to find refuge in unflooded areas for about 2 M years. This splitagrees with an increased asymmetry and heterochromatin amount, and decrease inkaryotype length and chromosome size. Thus, when the two Nierembergia ancestral lineages were isolated, major divergencesoccurred in chromosomal evolution, and then each linage underwent speciationseparately, with relatively minor changes in chromosomal characteristics.