Cytotaxonomy and geographic distribution of cytotypes of species of the South American genus Chrysolaena (Vernonieae, Asteraceae).

ANGULO MARÍA BETIANA; VIA DO PICO GISELA M.; DEMATTEIS, M.; PÉREZ YANINA DE JESÚS

JOURNAL OF SYSTEMATICS AND EVOLUTION

SCIENCE PRESS

Lugar: Marrickville NSW; Año: 2019 vol. 57 p. 451 - 467

0529-1526

Understandingspeciation and biodiversity patterns in plants requires knowledge of thegeneral role of climate in allowing polyploids to escape competition andpersist with their diploid progenitors. This is a particularly interestingissue in widespread species that present multiple ploidy levels and occuracross a heterogeneous environment. Chrysolaena (Vernonieae, Asteraceae) is acytogenetically very diverse genus, with significant interspecific andintraspecific ploidy level variation and with continuous distribution acrossSouth America. No previous studies have summarized chromosome count data ofChrysolaena or addressed the cytogeography of the genus. Ploidy level ofChrysolaena species was determined by chromosome counting during mitosis and/ormeiosis; the geographic distribution of cytotypes was examined and the correlationsbetween the distribution of particular cytotypes and current ecologicalconditions were evaluated. A total of 43 new chromosome counts and five ploidylevels (2x, 4x, 6x, 7x, 8x) were reported. The chromosome number of C.cordifolia (2n=7x=70) and a new cytotype for C. propinqua var. canescens(2n=4x=40) are reported for the first time. Three geographic areas with highdiversity of cytotypes and species were detected. The results obtained do notsuggest a clear distribution pattern that depends on climatic factors forChrysolaena populations. However, a geographic pattern was identified in thedistribution of ploidy levels, with diploid species presenting a morerestricted distribution than polyploidy species.