The evolution of chromosome number during the diversification of the tribe Vernonieae (Asteraceae)

CHALUP LAURA; ANGULO MARIA BETIANA; FLORENTIN, JAVIER; DEMATTEIS MASSIMILIANO

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2022

0024-4074

Changes in chromosome number have played an important role in thediversification and evolution of angiosperms. In the Asteraceae family, the tribeVernonieae is one of the most variable groups from the chromosome point of view.Initially, the chromosome numbers n= 9 and 10 characterized the Old World, whereas n=14, 16, 17, 18 characterized the New World. However, this scenario was altered withreports of new chromosome numbers, but the events responsible for this large variationremain unknown. We analyze the phylogeny of the Vernonieae within a temporalframework, assessing its patterns of diversification and establishing possible relationshipswith chromosome events. Chromosomal evolution was analyzed with ChromEvol, froma phylogenetic tree dated in BEAST. Shifts in diversification rates using Bayesiananalysis of macroevolutionary mixtures were inferred. The Vernonieae originated ~46Myr and the diversification rate increased sharply in ~11 Myr after the Mid MioceneClimatic Optimum had occurred. The ancestral chromosome number for the tribe was n=10, which remained stable for Old World taxa, whereas n= 9 was the ancestralnumber for New World species. The tribe underwent 30 32 chromosome rearrangementsthroughout its evolutionary history, with dysploidy and polyploidy being the events thatcould explain the observed diversification pattern.