Sex determination in varanids, Gila monsters, beaded lizards, and other anguimorphan lizards is still poorly understood. Sex chromosomes were reported only in a few species based solely on cytogenetics, which precluded assessment of their homology. We uncovered Z-chromosome-specific genes in varanids from their transcriptomes. Comparison of differences in gene copy numbers between sexes across anguimorphan lizards and outgroups revealed that homologous differentiated ZZ/ZW sex chromosomes are present in Gila monsters, beaded lizards, alligator lizards, and a wide phylogenetic spectrum of varanids. However, these sex chromosomes are not homologous to those known in other amniotes. We conclude that differentiated sex chromosomes were already present in the common ancestor of Anguimorpha living in the early Cretaceous or even in the Jurassic Period, 115-180 Ma, placing anguimorphan sex chromosomes among the oldest known in vertebrates. The analysis of transcriptomes of Komodo dragon (Varanus komodoensis) showed that the expression levels of genes linked to anguimorphan sex chromosomes are not balanced between sexes. Besides expanding our knowledge on vertebrate sex chromosome evolution, our study has important practical relevance for breeding and ecological studies. We introduce the first, widely applicable technique of molecular sexing in varanids, Gila monsters, and beaded lizards, where reliable determination of sex based on external morphology is dubious even in adults.

Department of Ecology Faculty of Science Charles University Prague Czech Republic

Prague Zoological Garden Prague Czech Republic

Citace poskytuje Crossref.org

Sex Chromosome Turnovers and Stability in Snakes

Cytogenetic Analysis of Satellitome of Madagascar Leaf-Tailed Geckos

Heteromorphic ZZ/ZW sex chromosomes sharing gene content with mammalian XX/XY are conserved in Madagascan chameleons of the genus Furcifer

Madagascar Leaf-Tail Geckos (Uroplatus spp.) Share Independently Evolved Differentiated ZZ/ZW Sex Chromosomes

ZZ/ZW Sex Chromosomes in the Madagascar Girdled Lizard, Zonosaurus madagascariensis (Squamata: Gerrhosauridae)

Do male and female heterogamety really differ in expression regulation? Lack of global dosage balance in pygopodid geckos

Sex chromosome evolution among amniotes: is the origin of sex chromosomes non-random?

A brief review of vertebrate sex evolution with a pledge for integrative research: towards 'sexomics'

Are Geckos Special in Sex Determination? Independently Evolved Differentiated ZZ/ZW Sex Chromosomes in Carphodactylid Geckos

Cytogenetic Evidence for Sex Chromosomes and Karyotype Evolution in Anguimorphan Lizards

With or Without W? Molecular and Cytogenetic Markers are Not Sufficient for Identification of Environmentally-Induced Sex Reversal in the Bearded Dragon

Poorly differentiated XX/XY sex chromosomes are widely shared across skink radiation

Independent Evolution of Sex Chromosomes in Eublepharid Geckos, A Lineage with Environmental and Genotypic Sex Determination

Evolutionary Variability of W-Linked Repetitive Content in Lacertid Lizards

Sex is determined by XX/XY sex chromosomes in Australasian side-necked turtles (Testudines: Chelidae)

ZZ/ZW Sex Determination with Multiple Neo-Sex Chromosomes is Common in Madagascan Chameleons of the Genus Furcifer (Reptilia: Chamaeleonidae)

Genome of the Komodo dragon reveals adaptations in the cardiovascular and chemosensory systems of monitor lizards