Natural hybridisation between a deciduous (Nothofagus antarctica, Nothofagaceae) and an evergreen (N. dombeyi) forest tree species as evidenced by morphological and isoenzymatic traits

MARINA STECCONI; PAULA MARCHELLI; JAVIER PUNTIERI; PABLO PICCA; LEONARDO GALLO

ANNALS OF BOTANY

Academic Press

Lugar: Londres; Año: 2004 vol. 94 p. 775 - 786

0305-7364

·        Trees with a partial leaf-shedding pattern and other morphological features a priori considered intermediate between those of the deciduous Nothofagus antarctica (G. Forster) Oersted and the evergreen N. dombeyi (Mirb.) Oersted (Nothofagaceae) were found in nature. The hybridisation between a deciduous and an evergreen species of Nothofagus had not been cited so far in natural communities. ·        The putative hybrids and the two presumed parental species were compared using fourteen enzyme systems as well as shoot, leaf and reproductive morphology. ·        Six enzyme systems showed good resolution (MDH, IDH, SKDH, 6-PGDH, GOT and PGI) and in four of them (PGI, MDH-B, SKDH and 6-PGDH) the putative hybrids were intermediate between N. antarctica and N. dombeyi. The putative hybrids were intermediate between both species regarding leaf vernation, outline and venation, variation in leaf shape (length/width) with position on the parent shoot and in staminate inflorescences and cupule morphology. For other morphological traits, the putative hybrids were not intermediate between both species although differentiation among the three entities was clear. ·        Isoenzymatic and morphological data sets support the idea of the hybrid nature (probably F1 generation) of the semi-deciduous trees found. Nothofagus antarctica and N. dombeyi would be more closely related than previously assumed. Natural hybridisation between a deciduous and an evergreen species of Nothofagus, constitutes an additional proof to the previously reported evidences that reject the use of leaf-shedding pattern in infrageneric classifications of Nothofagus spp.