Effects of interspecific recombination on functional traits in trees revealed by metabolomics and genotyping-by-resequencing

Abstract

Background : Understanding the potential and limits of recombination in adaptive evolution is of great interest to evolutionary biology. New (ultra-) high-throughput technologies in metabolomics and genomics hold great promise for addressing these questions, but their use in interspecific hybrids remains largely unexplored. Aims : Our goal was to test if recombination between the highly divergent genomes of Populus alba and P. tremula has the potential to contribute to the standing variation for functionally important chemical traits. Methods : We studied the metabolomes of interspecific hybrids by ultra-high-pressure liquid chromatography (UHPLC) coupled with quadrupole–time-of-flight (QTOF) mass spectrometry (MS) and initiated the characterisation of hybrid genomes by restriction site associated DNA (RAD) sequencing. Results : UHPLC-QTOF-MS indicated a complex ‘mosaic’ of chemical traits in recombinant hybrids and pointed to a heritable component for many of these. RAD sequencing confirmed the recombinant nature of natural hybrids previously characterised by microsatellites and suggested a complex history of recombination. Conclusions : It is likely that hybridisation has affected these species' genomes over several glacial cycles. Recombination holds great potential to create functionally relevant chemical variation in these trees. Nevertheless, correlations between chemical traits are not entirely broken up in recombinant hybrids, suggesting limits to adaptive evolution by genetic exchange.