Format: ORAL

Gonzalo Nieto Feliner

Real Jardín Botánico (RJB), CSIC, Madrid, Spain

The complexity of natural hybridization and its corollarythe difficulty of unraveling hybridization scenarios and understanding their impact on the evolution of plant groupsare mainly due to two causes. Hybridization is an open process that can lead to different outcomes, from no effect in sterile of unfit hybrid offspring to hybrid speciation, or adaptive introgression. The dynamism of hybridized genomes is higher than that of non-hybridized genomes on short time scales after hybridization, and this may also be true on longer time scales (ancient hybridization). This dynamism, which obscures the initial traces of hybridization, is driven by the genetic adjustments required following the merger of two differentiated genomes, a process that involves coping with genic incompatibilities and purging the minority genome. In the medium and long term, however, it can be also fueled by standard evolutionary mechanisms such as adaptation in interaction with the environment. There is one consequence of this whole situation that has been insufficiently discussed: how complexity can deceive the researcher along the process of inquiry, and whether some steps can be anticipated whenever new cases of hybridization are unveiled. This presentation discusses how meandering investigations that aim to shed light on hybridization scenarios might actually be, using three Iberian angiosperm groups that represent contrasting cases. In Armeria, the benefits of bidirectional introgression for two species in a coastal southern Spanish hybrid zone were inferred after several phylogeographic studies. The Iberian endemic Phalacrocarpum illustrates the challenge of reconstructing hybridization occurring at different time scales. Arenaria sect. Plinthine epitomizes complexity resulting from polyploidy combined with hybridization. The incorporation of genomic data and new analytical techniques has led to a gradual improvement in this subject. However, the lack of universal models is a major obstacle to our advance in the elucidation of hybridization scenarios.