Interspecific and intergeneric hybridization among South-American Discaria and Ochetophila (Rhamnaceae)

MEDAN D., M. ARBETMAN, E. CHAIA & A.C. PREMOLI

Bariloche

Congreso; VI Southern Connection Congress; 2010

In gondwanic Discaria Hook., phenotypically intermediate individuals exist between D. chacaye and D. articulata, and between D. chacaye and the related Ochetophila trinervis. We tested the hypothesis of hybridization in open forests of northern Patagonia, Argentina. We used neutral markers (nuclear by four polymorphic isozyme loci and maternally inherited trnL/trnF cpDNA intergenic spacer) and morphological features (leaf and reproductive traits) on all presumed parental species and 2 putative hybrids. We also studied flowering phenology, pollinators, and we performed cross-pollination experiments. Isozyme cluster analyses revealed that putative hybrids were closer to D. chacaye. Parental D. chacaye and D. articulata and its hybrid shared the same cpDNA haplotype, while morphologically the hybrid was similar to D. articulata. The hybrid between D. chacaye and O. trinervis had the haplotype of the latter, but was morphologically closer to D. chacaye. Flowering phenology was sequential, O. trinervis flowering latest. D. chacaye had 20 pollinators in common with D. articulata and 10 with O. trinervis. Seeds were obtained when crossing D. articulata pollen with D. chacaye ovules, and D. chacaye pollen with O. trinervis ovules, but only the first ones germinated. Our results confirm intra- and intergeneric hybridization in Rhamnaceae.