bioRxiv preprint doi: https://doi.org/10.1101/2020.10.23.335596; this version posted January 28, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Dynamics of sex chromosome evolution in a rapid radiation of cichlid fishes Athimed El Taher1, Fabrizia Ronco1, Michael Matschiner1,2,3, Walter Salzburger1, Astrid Böhne1,4* 1Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, Switzerland 2Department of Palaeontology and Museum, University of Zurich, Zurich, Switzerland. 3Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo, Norway. 4Center for Molecular Biodiversity Research, Zoological Research Museum Alexander Koenig, Bonn, Germany *e-mail:
[email protected] 1 bioRxiv preprint doi: https://doi.org/10.1101/2020.10.23.335596; this version posted January 28, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. Abstract Sex is a fundamental trait that is determined, depending on the species, by different environmental and/or genetic factors, including various types of sex chromosomes. While the functioning and emergence of sex chromosomes have been explored in species scattered across the eukaryotic tree of life, little is known about tempo and mode of sex chromosome evolution in closely related species. Here, we examine the dynamics of sex chromosome evolution in an archetypical example of adaptive radiation, the cichlid fishes of African Lake Tanganyika. Through inspection of male and female genomes from 244 cichlid taxa and the analysis of transcriptomes from 66 taxa, we identify signatures of sex chromosomes in 79 taxa, involving 12 different linkage groups.