Patrizia Sebastian

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Dipl. biol. Patrizia Sebastian

Systematic Botany
Ludwig-Maximilians-University of Munich
Menzinger Str. 67
80638 Munich
Germany

E-Mail: p.sebastian@biologie.uni-muenchen.de

My PhD thesis

The expansion and radiation of the Sicyos lineage in the neotropics, Hawaii, and Australia, and the evolution of an exceptionally reduced chromosome number in the Asian/Australian Cucumis clade

My doctoral project will have two foci, (i) chromosome evolution in the Asian/Australian Cucumis clade, which includes the cucumber, C. sativus; and (ii) the biogeographic history of a predominantly neotropical clade of cucurbits that has produced small radiations in Hawaii and Australia. Until 2007, Cucumis was thought to be an African clade with only two species in Asia, among them C. sativus. Molecular data, including sequences I have produced, instead revealed 13 Asian and Australian species as closest to C. sativus. Most have never had their chromosomes counted; C. sativus has an unusually low haploid number of n = 7. I am now collecting and bringing into cultivation the Asian and Australian cucumber relatives in order to understand the pathway that lead to n = 7, using molecular and microscopic methods. Similar to Cucumis, with its three Australian species, my other focal clade, the neotropical Sicyos lineage with c. 62 species, also have reached Australia, where they have three species currently placed in Sicyos. Sicyos also has 14 species on the Hawaiian archipelago. Using a molecular topology and molecular clock dating, I plan to infer dispersal directions and radiation times.