Understanding the occurrence of monoecy and dioecy in L. and Ecballium L. ()

Stefanie M. Volz and Susanne S. Renner [email protected] Fakultaet fuer Biologie, Ludwig-Maximilians Universitaet Muenchen, D-80638 Munich

We are using the small West Eurasian Cucurbitaceae genera Bryonia (Zaunrübe) and Ecballium (Spritzgurke) monoecious dioecious to study the occurrence and causes of within-species

B. dioica male , climbing sexual system switches, in this case between monoecy over bushes and dioecy. Bryonia and Ecballium form an isolated and relatively basal clade in the Cucurbitaceae family tree1.

B. dioica male plant, climbing Both genera consist of taxonomically problematic over bushes species/subspecies of which most are dioecious3. Even monoecious species have!dioecious populations in parts of their range. Monoecious accessions from both genera are highlighted in orange in the tree. ! monoecy seems to have arisen from dioecy at least twice independently in Bryonia. The monoecious B. alba is invasive in North America and New Zealand. The morphological distinct B. verrucosa from the Canary Islands is sister to all other species of Bryonia. It is dioecious, as are the majority of closely related Cucurbitaceae.

Maximum likelihood tree calculated under the model Kimura-3-parameters + unequal base frequencies + proportion of invariable sites, the best model for the data according to DT_ModSel2. Bootstrap values are from a 1000 replicates of heuristic searching. Both analyses used SPR- swapping and simple sequence addition.

A male plant of Bryonia dioica 4 A monoecious growing over bushes 5 Ecballium elaterium .

Three chloroplast regions - the psbA-trnH spacer, the trnH-atpA spacer, and the trnL intron and spacer (1838 aligned bases) - were sequenced in 58 accessions of Bryonia, seven of Ecballium, and a related Himalayan clade as an outgroup. Chloroplast DNA haplotypes are color-coded as in the tree.

References 1. Zhang, L-B., M. Simmons, A. Kocyan, and S. S. Renner. Phylogeny of the based on DNA sequences of nine loci from three genomes: implications for morphological and sexual system evolution. Mol. Phyl. Evol. (accepted pending revision). 2. Minin, V., Z. Abdo, P. Joyce, and J. Sullivan. 2003. Performance based selection of likelihood models for phylogeny estimation. Syst. Biol. 52:1–10. 3. Jeffrey, C. 1969. A review of the Bryonia L. (Cucurbitaceae) Kew Bulletin 23:441-461. 4. Photo M. Dorken. 5. Photo G. Hausner.