Doktorarbeit: Carnivory in Lamiales: Phylogeny, taxonomy, and chloroplast genome evolution

Status abgeschlossen am Nov 1, 2011
Student Schäferhoff, Bastian
Bewertende Einrichtung Evolution und Biodiversität der Pflanzen
Institut für Evolution und Biodiversität
WWU Münster
Hüfferstraße 1
48149 Münster
Germany
URL http://d-nb.info/1047612925

Zusammenfassung

The phylogenetic analyses of the three marker dataset of Lamiales in chapter one revealed a highly resolved tree of the order. Plocospermataceae branch first in the order, followed by a clade including Carlemanniaceae and Oleaceae. Tetrachondraceae and a goup of Calceolariaceae plus Gesneriaceae branch subsequently. The results allow reconstructing the evolution of important morphological characters, such as symmetry and merosity. There is clear evidence for the independent evolution of carnivory in Lentibulariaceae and Byblidaceae. The more derived branches of the tree are less resolved which is suggested to be due to a rapid radiation of Lamiales, which fixed only very few mutations on DNA level.

Linderniaceae are a group separate from Scrophulariaceae, and genus Lindernia has turned out to be highly polyphyletic in its current circumscription (see Chapter two). Genera like Bryodes and Psammetes are found nested in other genera, making those paraphyletic. We suggest a new taxonomic treatment for the family including the new genus Linderniella and new combinations of the genera Bonnaya, Craterostigma, Torenia, and Vandellia. The phylogeny found is in line with morphological characters as seed alveolation or flower morphology.

In chapter three, six major clades in the carnivorous genus Pinguicula were recovered corresponding largely to geographic radiations. We find this in trees from plastid DNA sequences as well as in data from nuclear DNA for the first time. Chromosome counts are analyzed in a phylogenetic context for the first time and further support the phylogenies from molecular data. None of the subgenera and sections of the previous taxonomic classification has shown to be monophyletic.

Sampling 105 species from 27 of the 35 currently accepted sections, chapter four of this study covers the vast majority of the generic diversity. Three major clades in the genus, which had recently been assigned to subgeneric rank, are recovered here. Utricularia is ancestrally terrestrial, and evolved various life forms, and each of them originated more than once. Members of the genus are found all over the world (except arid regions), but only the aquatic section Utricularia has a wide distribution. We find a new clade characterized by the lack of bracteoles that includes species from sections Utricularia, Lecticula, Setiscapella, Avesicaria, Mirabiles, Steyermarkia, Vesiculina, and Nelipus. The existing taxonomic treatment has shown to represent monophyletic grouping in the most cases, and suggestions are made to keep all sections monophyletic.

The trees of genus Genlisea are highly resolved and supported (Fleischmann et al. 2010, see Chapter 5). The two major clades found in the genus correspond to the two subgenera Tayloria and Genlisea, earlier substantiating this subgeneric treatment. The exclusively South American subgenus Tayloria branches first, suggesting the origin of the genus in South America. The African species form a paraphyletic group within subgenus Genlisea, which implies a resettlement of South America from Africa most likely by long distance dispersal.

In the subgenus Genlisea, the two new sections Recurvatae and Africanae were described as first taxonomical results towards a complete revision of the genus.

One entire chloroplast genome of each of the genera of Lentibulariaceae was sequenced using 454 pyrosequencing (see Chapter six). The structure of the genomes and the gene order is that of normal autotrophic angiosperms.The gene content is similar to that of autotrophous angiosperms except the lack of ndh sub-units in Pinguicula and Genlisea, and lack of ycf1 in its typical length in all three genera. The genome size in Pinguicula and Genlisea is thereby shrunk by about 5 to 9%. An analysis of relative substitution rates of the protein coding genes of the chloroplast genomes unraveled an increasing number of accelerated genes from Pinguicula via Utricularia to Genlisea.