INVESTIGADORES
MATHIASEN Paula
congresos y reuniones científicas
Título:
Nothofagus species merge and diverge in complex landscapes
Autor/es:
PREMOLI, ANDREA C.; MATHIASEN, PAULA; ACOSTA, M. CRISTINA
Lugar:
Bento Gonçalves, Rio Grande do Sul, Brazil
Reunión:
Simposio; IV Brazilian Symposium on Plant Molecular Genetics; 2013
Resumen:
Forest landscapes of Patagonia have suffered from large-scale
modifications such as a presence of physical barriers that have affected
patterns of gene flow of tree species. This is in addition to changes
in climate and environmental heterogeneity that produced ecologically
divergent selective forces in sympatric taxa. Subgenus Nothofagus is
restricted to temperate areas of South America. It consists of five
tree species, with distinct life histories traits, most of which are
regionally widespread. Species of subgenus Nothofagus are dominant tree
taxa in all forest types. They are morphologically and ecologically
distinct, although pollen undistinguishable. Even though they grow
under contrasting environmental settings they produce hybrids in
sympatry or after disturbance. We used nuclear and chloroplast DNA
(cpDNA) sequences in combination with molecular dating methods to
analyze patterns of among- and within-species divergence throughout
their entire range in the southern Andes. Phylogenetic analyses
yielded widespread nuclear and chloroplast discordance. Whereas
nuclear DNA depicted phylogenetic relationships, chloroplast DNA
yielded a shared geographic structure significantly controlled by
geology. Concordant cpDNA was due to ancient hybridization and
repeated chloroplast capture. Paleobasins and marine transgressions
that occurred during the late Tertiary produced long-lasting vicariant
events while pre-Miocene massifs functioned as land-dispersal
corridors. Hybridization and introgression facilitated long-distance
pollen dispersal followed by a selective regime favoring each
ecologically-distinct Nothofagus. Adaptive divergence in the absence
of complete reproductive barriers in spatial and temporally
heterogeneous environments of Patagonia acted as reassurance for
long-term species persistence.