Comparative genomics reveals an outstanding sex chromosome diversity in cichlid fishes driven by genomic novelties and convergent evolution
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1
University of Basel, Zoological Institute, Switzerland
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2
Paleontological Institute and Museum, Faculty of Mathematics and Natural Sciences, University of Zurich, Switzerland
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3
Centre for Ecological and Evolutionary Synthesis, Faculty of Mathematics and Natural Sciences, University of Oslo, Norway
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4
Zoological Research Museum Alexander Koenig (LG), Center for Molecular Biodiversity Research (ZMB), Germany
Sexual reproduction is ancient and almost universal in the eukaryotic kingdom. However, the mechanisms that actually determine male or female sex are highly divers encompassing a variety of extrinsic and intrinsic drivers. Intrinsic factors, commonly referred to as genetic sex determination, comprise systems as simple as a single base pair difference between the sexes to highly differentiated sex chromosomes. Why sex-determining systems change frequently in some taxa, whereas the same sex chromosome pair persists over long evolutionary time in others, remains an open question. With ~3000 species, cichlid fishes are one of the largest vertebrate families and an extraordinary example of adaptive radiations. If different sex-determining mechanisms contribute to the species richness of this fish lineage is largely unknown. The oldest and most diverse African cichlid assemblage is the one of Lake Tanganyika, which consists of 250 endemic species. Using whole genome sequencing, comparative genomics and expression data, we investigate the genetic basis of sex determination and the evolution of sex chromosomes in this radiation. We identified at least 28 sex chromosome transitions in cichlids with a transition rate of 0.19 per million years. To the best of our knowledge this is the highest transition rate so far described. We show that closely related species can have different sex chromosomal systems indicative of recent turnover events. On the other hand, it also seems that particular chromosomes evolved convergently as sex chromosomes in distantly related cichlid lineages. Chromosomal fusions likely played a role in cichlid sex chromosome evolution. Cichlids perfectly exemplify the diversity as well as the constraints of sex chromosome evolution and can reveal the forces driving the evolution of sex-determining systems.
Acknowledgements
Calculations were performed at sciCORE (http://scicore.unibas.ch/) scientific computing center at University of Basel, with support by the SIB - Swiss Institute of Bioinformatics.
Keywords:
Cichlid,
sex chromosome,
adaptive radiation,
speciation,
Lake Tanganyika cichlid fishes,
Comparative genomics,
Transcriptomics
Conference:
XVI European Congress of Ichthyology, Lausanne, Switzerland, 2 Sep - 6 Sep, 2019.
Presentation Type:
Oral
Topic:
EVOLUTIONARY GENOMICS OF FISHES
Citation:
El Taher
A,
Matschiner
M,
Ronco
F,
Salzburger
W and
Böhne
A
(2019). Comparative genomics reveals an outstanding sex chromosome diversity in cichlid fishes driven by genomic novelties and convergent evolution.
Front. Mar. Sci.
Conference Abstract:
XVI European Congress of Ichthyology.
doi: 10.3389/conf.fmars.2019.07.00040
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Received:
17 Jun 2019;
Published Online:
14 Aug 2019.
*
Correspondence:
Dr. Astrid Böhne, University of Basel, Zoological Institute, Basel, CH-4001, Switzerland, a.boehne@leibniz-zfmk.de