P2007-02: Evolution und secundary structure of the nrDNS-region ITS of Tillandsia s. l. (Bromeliaceae): Relationships between sequence-alignments, phylogeny and ecological-adaptive variability
Project leader :
We study the evolutionary behaviour of the tandem-repetitive sequence fraction ITS (internal transcribed spacer) and the influence of the secondary structure on sequence alignments in phylogenetic analyses in Tillandsia using ITS1 and ITS2 as non coding sequences of the nuclear genome in combination with the low copy nuclear gene PRK (Exons and Itrons) and seven marker sequences of the chloroplast genome.
Degrees of variability of the copies within nuclear genomes should allow detect hybridization events and to estimate the speed of sequence homogeneisation. Primer and PCR optimisations shall allow to explain why ITS was hitherto very difficult to sequence in Tillandsia. ITS data compared with PRK and cpDNA will be used to interpret hybridisation and reticulate evolution within the genus.
The conflict of the cpDNA phylogeny with classical taxonomy will be tested against the new molecular data. Sequence comparisons will provide the substitution rates of the used markers and will indicate which sequences are most useful for phylogenetic analyses in Tillandsia.
This mega-genus urgently needs re-definition of its larger subunits as natural entities using new and underestimated morphological and ecological characters. Convergent ecological adaptations will be separated from classification relevant characters.
Only with this re-definition reliable interpretations of the distribution patterns and evolutionary lineages will be possible. The re-classification will reflect true biodiversity and species relationships which is essential also for conservation items as well as for calculating breeding potentials.
