title: The Evolutionary Dynamics of Genes and Genomes:  Copy Number Variation of the Chalcone Synthase Gene in the Context of Brassicaceae Evolution
creator: Ding, Liza Paola
subject: 570
subject: 570 Life sciences
subject: 580
subject: 580 Botanical sciences
description: The Brassicaceae (Mustards, Cruciferae) are a cosmopolitan family comprising 370 genera and around 3660 species assigned to lately 50 tribes. The tribal system was originally based on solely homoplasious morphological character traits and reaches back to the early 19th century. De Candolle introduced the first tribal classification of the family nearly 200 years ago (1821) containing 21 partly still utilised classifications nowadays. Although labelling seems to be up to date, generic delimitations have been under permanent significant substitution and replacement. The tribes are arranged in three major monophyletic lineages and some additional small groups. The relationships within and between these lineages have not been resolved very clearly yet, as the Brassicaceae are characterised by frequently occurring hybridisation and polyploidisation events. This could be either the result of early and rapid radiation events or perhaps be the product of reticulate evolution, lediang to conflicting gene trees (KOCH & AL-SHEHBAZ 2009).  This lack of resolution could in parts be resolved via the application of the nuclear encoded chalcone synthase gene (chs) on 39 of the Cruciferous tribes. Several small-scale tribal-specific duplication events, including age estimations, could be detected giving insight into the evolutionary history of this molecular single- or low-copy gene. Most definitely a tendency towards diploidisation is proven by purifying selection as well as accelerated synonymous substitution rates among this family resulting sooner or later in the reduction of preliminary multiplied chs loci. Supposedly, chs is single-copy in most diploid mustard taxa.  The determination of orthologous and paralogous gene copies exposed to be of essential cause as it could be proven that yet functional but fluctuating DNA sequences demonstrate a huge impact on divergence time estimates as well as on any other extrapolation applying nucleotide or amino acid data. However, all crown age estimations calculated with diverse approaches resulted in reasonable output, dating the most recent common ancestor (tmrca) of the family to the Late Miocene or Oligocene.  Adjustments of the DNA sequences resulted in a well-resolved thoroughgoing gene tree phylogeny facilitating established taxonomic as well as phylogenetic achievements and do, moreover, hint to further ambiguities which have to be clarified by the commitment of additional marker systems.
date: 2016
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/17893/1/Dissertation_Ding_Liza_Paola.pdf
identifier: DOI:10.11588/heidok.00017893
identifier: urn:nbn:de:bsz:16-heidok-178932
identifier:   Ding, Liza Paola  (2016) The Evolutionary Dynamics of Genes and Genomes: Copy Number Variation of the Chalcone Synthase Gene in the Context of Brassicaceae Evolution.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/17893/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng