ACKNOWLEDGEMENTS

We gratefully acknowledge help from all members of the Derome and Val laboratory. Thank you to the IBIS Plateforme d’Analyse Génomiquefor the sequencing and to ICMBIO/Instituto Chico Mendes de Conservação da Biodiversidade for in situ support for fish collection and for issuing the permit to transport biological samples (permit number 29837/18). This research was part of the ADAPTA project at INPA and was supported by the INCT ADAPTA (CNPq/FAPEAM) and INPA/MCTI grants to ALV (ORCID: 0000‐0002‐3823‐3868), the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery grant (grant #6333) and the Canada-Brazil Awards Joint Research Project to ND (ORCID: 0000‐0002‐2509‐6104), and the NSERC BESC M Alexander-Graham-Bell, the FRQNT Master Scholarship grant, the MITACS GlobaLink grant, the Ressources Aquatiques Québec (RAQ) internship grant and the André Darveau grant to NL (ORCID: 0000-0003-1198-9435). Additionally, we would like to thank Martin Laporte, Tommy Pontbriand and Jérémie Boucher-Fontaine for their help reviewing the manuscript.