Abstract Detail

Recent advances in phylogeny and systematics of Brassicaceae 

Koch, Marcus [1], Hohmann, Nora [2].

A time-calibrated road map of Brassicaceae evolutionary history.

The Brassicaceae or mustard family (= crucifers) is not only including a number of important crop plants such as the various Brassica species, but also includes numerous important model species in plant and evolutionary biology. Among them is, of course, Arabidopsis thaliana as the most important representative, but also other species and genera such Arabidopsis halleri, Thellungiella, Capsella or Arabis are important and emerging systems to study traits and characters not to be studied in Arabidopsis thaliana. With the rapidly increasing amount of any type of data collected from within the Brassicaceae there is a rapid process to establish the entire family as model for comparative evolutionary research. However, any evolutionary hypothesis is fully depending on a reliable reconstruction of the past, and, therefore, a reliable timeline of major splits of Brassicaceae evolution is highly desirable. Different divergence time estimates were proposed within the past 15 years, but all of them are biased either by unsufficient fossil calibration or limited DNA sequence information. Herein we present a first and comprehensive time-calibrated framework with some important divergence time estimates presented for the Brassicaceae based on whole-chloroplast genome sequence data. Considering the whole clade of “Superrosidae” with fully resembled chloroplast genome data, diversification of Brassicaceae crown group started 32 million years ago at the transition from Eocene to Oligocene, which demarks the onset of major environmental changes with general and rapid decline of temperature and global increase in ice volumes. Additional and major deep evolutionary splits are dated of about 20 million years ago, also indicating a transition, from Oligocene to Miocene, with increasing draught and aridity and also transient glaciation event. Following this time-line the age of the Arabidopsis stem group is 5.97 million years, but the onset of major radiation within the genus Arabidopsis occurred less than 2 million years ago during Pleistocene glaciation and deglaciation cycles. In conclusion, our timeline and according correlation with major environmental shifts is fully in accordance with present day preferences of the majority of Brassicaceae taxa for cool-temperate and dry conditions.

1 - Heidelberg University, COS, Diversity and Plant Systematics, Im Neuenheimer Feld 345, Heidelberg, Germany
2 - Heidelberg University, COS, Diversity and Plant Systematics, Im Neuenheimer Feld , Heidelberg, Germany

Keywords:
Divergence time estimates
Brassicaceae
Superrosids.

Presentation Type: Colloquium Presentations
Session: C2
Location: Salon 8/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:45 PM
Number: C2004
Abstract ID:96
Candidate for Awards:None