Organisms Diversity & Evolution

, Volume 13, Issue 1, pp 1–13

Divergence time estimation in Cichorieae (Asteraceae) using a fossil-calibrated relaxed molecular clock

Authors

    • Institute of Botany, Department of Integrative Biology and Biodiversity ResearchUniversity of Natural Resources and Life Sciences
    • Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de Sevilla
  • Birgit Gemeinholzer
    • Botanic Garden and Botanical Museum Berlin-DahlemFreie Universität Berlin
    • Justus-Liebig-Universität GießenAG Spezielle Botanik
  • Holger Zetzsche
    • Botanic Garden and Botanical Museum Berlin-DahlemFreie Universität Berlin
  • Stephen Blackmore
    • Royal Botanic Garden Edinburgh
  • Norbert Kilian
    • Botanic Garden and Botanical Museum Berlin-DahlemFreie Universität Berlin
  • Salvador Talavera
    • Departamento de Biología Vegetal y Ecología, Facultad de BiologíaUniversidad de Sevilla
Original Article

DOI: 10.1007/s13127-012-0094-2

Cite this article as:
Tremetsberger, K., Gemeinholzer, B., Zetzsche, H. et al. Org Divers Evol (2013) 13: 1. doi:10.1007/s13127-012-0094-2

Abstract

Knowing the age of lineages is key to understanding their biogeographic history. We aimed to provide the best estimate of the age of Cichorieae and its subtribes based on available fossil evidence and DNA sequences and to interpret their biogeography in the light of Earth history. With more than 1,550 species, the chicory tribe (Cichorieae, Asteraceae) is distributed predominantly in the northern Hemisphere, with centres of distribution in the Mediterranean region, central Asia, and SW North America. Recently, a new phylogenetic hypothesis of Cichorieae based on ITS sequences has been established, shedding new light on phylogenetic relationships within the tribe, which had not been detected so far. Cichorieae possess echinolophate pollen grains, on the surface of which cavities (lacunae) are separated by ridges. These lacunae and ridges show patterns characteristic of certain groups within Cichorieae. Among the fossil record of echinolophate pollen, the Cichorium intybus-type is the most frequent and also the oldest type (22 to 28.4 million years old). By using an uncorrelated relaxed molecular clock approach, the Cichorieae phylogenetic tree was calibrated with this fossil find. According to the analysis, the tribe originated no later than Oligocene. The species-rich core group originated no later than Late Oligocene or Early Miocene and its subtribes diversified no later than Middle/Late Miocene or Early Pliocene—an eventful period of changing geological setting and climate in the Mediterranean region and Eurasia. The first dispersal from Eurasia to North America, which resulted in the radiation of genera and species in North America (subtribe Microseridinae), also occurred no later than Middle or Late Miocene, suggesting the Bering land bridge as the route of dispersal.

Keywords

Bering land bridgeLactuceaeMioceneOligocenePollen evolutionUncorrelated relaxed molecular clock

Copyright information

© Gesellschaft für Biologische Systematik 2012