**Acknowledgements**

This research has been partially funded by the Spanish grants MINECO CGL2017- 84901-C2 and MICINN PID 2020-114273GB-C21. I warmly thank the scientific editor Karoly Nemeth and the IntexOpen reviewers for their comments, which have contributed to improve the manuscript. English text has been reviewed and revised by Grant George Buffett (www.terranova.barcelona).
