1
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Straková B, Kubička L, Červenka J, Kratochvíl L. Pivotal temperature is not for everyone: Evidence for temperature-dependent sex determination in three gecko species. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:597-605. [PMID: 38497303 DOI: 10.1002/jez.2808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/20/2024] [Accepted: 02/23/2024] [Indexed: 03/19/2024]
Abstract
The prevalence of environmental sex determination (ESD) in squamate reptiles is often overestimated in the literature. This is surprising because we have reliable data demonstrating ESD in only a few species. The documentation of ESD in three species of geckos presented here has significantly increased our knowledge, given that satisfactory evidence for ESD existed in only eight other gecko species. For the first time, we document the occurrence of ESD in the family Sphaerodactylidae. Our finding of unexpected variability in the shapes of reaction norms among geckos highlights that traditional descriptions using parameters such as pivotal temperature, that is, temperature producing a 50:50 sex ratio, are unsatisfactory. For example, the gecko Pachydactylus tigrinus lacks any pivotal temperature and its sex ratios are strongly female-biased across the entire range of viable temperatures. We argue for the effective capture of the relationship between temperature and sex ratio using specific nonlinear models rather than using classical simplistic descriptions and classifications of reaction norms.
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Affiliation(s)
- Barbora Straková
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lukáš Kubička
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Jan Červenka
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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2
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Pensabene E, Augstenová B, Kratochvíl L, Rovatsos M. Differentiated sex chromosomes, karyotype evolution, and spontaneous triploidy in carphodactylid geckos. J Hered 2024; 115:262-276. [PMID: 38366660 DOI: 10.1093/jhered/esae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/13/2024] [Indexed: 02/18/2024] Open
Abstract
Geckos exhibit derived karyotypes without a clear distinction between macrochromosomes and microchromosomes and intriguing diversity in sex determination mechanisms. We conducted cytogenetic analyses in six species from the genera Nephrurus, Phyllurus, and Saltuarius of the gecko family Carphodactylidae. We confirmed the presence of a female heterogametic system with markedly differentiated and heteromorphic sex chromosomes in all examined species, typically with the W chromosome notably larger than the Z chromosome. One species, Nephrurus cinctus, possesses unusual multiple Z1Z1Z2Z2/Z1Z2W sex chromosomes. The morphology of the sex chromosomes, along with repetitive DNA content, suggests that the differentiation or emergence of sex chromosomes occurred independently in the genus Phyllurus. Furthermore, our study unveils a case of spontaneous triploidy in a fully grown individual of Saltuarius cornutus (3n = 57) and explores its implications for reproduction in carphodactylid geckos. We revealed that most carphodactylids retain the putative ancestral gekkotan karyotype of 2n = 38, characterized by predominantly acrocentric chromosomes that gradually decrease in size. If present, biarmed chromosomes emerge through pericentric inversions, maintaining the chromosome (and centromere) numbers. However, Phyllurus platurus is a notable exception, with a karyotype of 2n = 22 chromosomes. Its eight pairs of biarmed chromosomes were probably formed by Robertsonian fusions of acrocentric chromosomes. The family underscores a remarkable instance of evolutionary stability in chromosome numbers, followed by a profound transformation through parallel interchromosomal rearrangements. Our study highlights the need to continue generating cytogenetic data in order to test long-standing ideas about reproductive biology and the evolution of genome and sex determination.
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Affiliation(s)
- Eleonora Pensabene
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Barbora Augstenová
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Lukáš Kratochvíl
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Michail Rovatsos
- Department of Ecology, Faculty of Science, Charles University, Prague, Czech Republic
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3
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Uno Y, Matsubara K. Unleashing diversity through flexibility: The evolutionary journey of sex chromosomes in amphibians and reptiles. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024; 341:230-241. [PMID: 38155517 DOI: 10.1002/jez.2776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 12/01/2023] [Accepted: 12/05/2023] [Indexed: 12/30/2023]
Abstract
Sex determination systems have greatly diversified between amphibians and reptiles, with such as the different sex chromosome compositions within a single species and transition between temperature-dependent sex determination (TSD) and genetic sex determination (GSD). In most sex chromosome studies on amphibians and reptiles, the whole-genome sequence of Xenopous tropicalis and chicken have been used as references to compare the chromosome homology of sex chromosomes among each of these taxonomic groups, respectively. In the present study, we reviewed existing reports on sex chromosomes, including karyotypes, in amphibians and reptiles. Furthermore, we compared the identified genetic linkages of sex chromosomes in amphibians and reptiles with the chicken genome as a reference, which is believed to resemble the ancestral tetrapod karyotype. Our findings revealed that sex chromosomes in amphibians are derived from genetic linkages homologous to various chicken chromosomes, even among several frogs within single families, such as Ranidae and Pipidae. In contrast, sex chromosomes in reptiles exhibit conserved genetic linkages with chicken chromosomes, not only across most species within a single family, but also within closely related families. The diversity of sex chromosomes in amphibians and reptiles may be attributed to the flexibility of their sex determination systems, including the ease of sex reversal in these animals.
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Affiliation(s)
- Yoshinobu Uno
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kazumi Matsubara
- Department of Bioscience and Biotechnology, Graduate School of Bioscience and Biotechnology, Chubu University, Kasugai, Aichi, Japan
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4
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Webster TH, Vannan A, Pinto BJ, Denbrock G, Morales M, Dolby GA, Fiddes IT, DeNardo DF, Wilson MA. Lack of Dosage Balance and Incomplete Dosage Compensation in the ZZ/ZW Gila Monster (Heloderma suspectum) Revealed by De Novo Genome Assembly. Genome Biol Evol 2024; 16:evae018. [PMID: 38319079 PMCID: PMC10950046 DOI: 10.1093/gbe/evae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 02/07/2024] Open
Abstract
Reptiles exhibit a variety of modes of sex determination, including both temperature-dependent and genetic mechanisms. Among those species with genetic sex determination, sex chromosomes of varying heterogamety (XX/XY and ZZ/ZW) have been observed with different degrees of differentiation. Karyotype studies have demonstrated that Gila monsters (Heloderma suspectum) have ZZ/ZW sex determination and this system is likely homologous to the ZZ/ZW system in the Komodo dragon (Varanus komodoensis), but little else is known about their sex chromosomes. Here, we report the assembly and analysis of the Gila monster genome. We generated a de novo draft genome assembly for a male using 10X Genomics technology. We further generated and analyzed short-read whole genome sequencing and whole transcriptome sequencing data for three males and three females. By comparing female and male genomic data, we identified four putative Z chromosome scaffolds. These putative Z chromosome scaffolds are homologous to Z-linked scaffolds identified in the Komodo dragon. Further, by analyzing RNAseq data, we observed evidence of incomplete dosage compensation between the Gila monster Z chromosome and autosomes and a lack of balance in Z-linked expression between the sexes. In particular, we observe lower expression of the Z in females (ZW) than males (ZZ) on a global basis, though we find evidence suggesting local gene-by-gene compensation. This pattern has been observed in most other ZZ/ZW systems studied to date and may represent a general pattern for female heterogamety in vertebrates.
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Affiliation(s)
- Timothy H Webster
- Department of Anthropology, University of Utah, Salt Lake City, UT, USA
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Annika Vannan
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Brendan J Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, USA
| | - Grant Denbrock
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Matheo Morales
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Department of Genetics, Yale University, New Haven, CT, USA
| | - Greer A Dolby
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Dale F DeNardo
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Melissa A Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ, USA
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5
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Pinto BJ, Nielsen SV, Sullivan KA, Behere A, Keating SE, van Schingen-Khan M, Nguyen TQ, Ziegler T, Pramuk J, Wilson MA, Gamble T. It's a trap?! Escape from an ancient, ancestral sex chromosome system and implication of Foxl2 as the putative primary sex-determining gene in a lizard (Anguimorpha; Shinisauridae). Evolution 2024; 78:355-363. [PMID: 37952174 PMCID: PMC10834058 DOI: 10.1093/evolut/qpad205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 10/25/2023] [Accepted: 11/08/2023] [Indexed: 11/14/2023]
Abstract
Although sex determination is ubiquitous in vertebrates, mechanisms of sex determination vary from environmentally to genetically influenced. In vertebrates, genetic sex determination is typically accomplished with sex chromosomes. Groups like mammals maintain conserved sex chromosome systems, while sex chromosomes in most vertebrate clades are not conserved across similar evolutionary timescales. One group inferred to have an evolutionarily stable mode of sex determination is Anguimorpha, a clade of charismatic taxa including monitor lizards, Gila monsters, and crocodile lizards. The common ancestor of extant anguimorphs possessed a ZW system that has been retained across the clade. However, the sex chromosome system in the endangered, monotypic family of crocodile lizards (Shinisauridae) has remained elusive. Here, we analyze genomic data to demonstrate that Shinisaurus has replaced the ancestral anguimorph ZW system on LG7 with a novel ZW system on LG3. The linkage group, LG3, corresponds to chromosome 9 in chicken, and this is the first documented use of this syntenic block as a sex chromosome in amniotes. Additionally, this ~1 Mb region harbors approximately 10 genes, including a duplication of the sex-determining transcription factor, Foxl2, critical for the determination and maintenance of sexual differentiation in vertebrates, and thus a putative primary sex-determining gene for Shinisaurus.
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Affiliation(s)
- Brendan J Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, United States
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, United States
| | - Stuart V Nielsen
- Department of Biological Sciences, Museum of Life Sciences, Louisiana State University-Shreveport, Shreveport, LA, United States
- Florida Museum of Natural History, University of Florida, Gainesville, FL, United States
| | - Kathryn A Sullivan
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, United States
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
| | - Ashmika Behere
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
| | - Shannon E Keating
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
| | | | - Truong Q Nguyen
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, Hanoi, Vietnam
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Thomas Ziegler
- Cologne Zoo, Cologne, Germany
- Department of Biology, Institute of Zoology, University of Cologne, Cologne, Germany
| | - Jennifer Pramuk
- Former affiliation: Woodland Park Zoo, Seattle, WA, United States
| | - Melissa A Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, United States
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ, United States
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, United States
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
- Bell Museum of Natural History, University of Minnesota, St Paul, MN, United States
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6
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Guo L, Kruglyak L. Genetics and biology of coloration in reptiles: the curious case of the Lemon Frost geckos. Physiol Genomics 2023; 55:479-486. [PMID: 37642275 DOI: 10.1152/physiolgenomics.00015.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 08/17/2023] [Accepted: 08/23/2023] [Indexed: 08/31/2023] Open
Abstract
Although there are more than 10,000 reptile species, and reptiles have historically contributed to our understanding of biology, genetics research into class Reptilia has lagged compared with other animals. Here, we summarize recent progress in genetics of coloration in reptiles, with a focus on the leopard gecko, Eublepharis macularius. We highlight genetic approaches that have been used to examine variation in color and pattern formation in this species as well as to provide insights into mechanisms underlying skin cancer. We propose that their long breeding history in captivity makes leopard geckos one of the most promising emerging reptilian models for genetic studies. More broadly, technological advances in genetics, genomics, and gene editing may herald a golden era for studies of reptile biology.
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Affiliation(s)
- Longhua Guo
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, United States
- Geriatrics Center and Institute of Gerontology, University of Michigan, Ann Arbor, Michigan, United States
| | - Leonid Kruglyak
- Department of Human Genetics, University of California, Los Angeles, California, United States
- Department of Biological Chemistry, University of California, Los Angeles, California, United States
- Howard Hughes Medical Institute, Chevy Chase, Maryland, United States
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7
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Pinto BJ, Nielsen SV, Sullivan KA, Behere A, Keating SE, van Schingen-Khan M, Nguyen TQ, Ziegler T, Pramuk J, Wilson MA, Gamble T. It's a Trap?! Escape from an ancient, ancestral sex chromosome system and implication of Foxl2 as the putative primary sex determining gene in a lizard (Anguimorpha; Shinisauridae). BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.05.547803. [PMID: 37461522 PMCID: PMC10349997 DOI: 10.1101/2023.07.05.547803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/23/2023]
Abstract
Although sex determination is ubiquitous in vertebrates, mechanisms of sex determination vary from environmentally- to genetically-influenced. In vertebrates, genetic sex determination is typically accomplished with sex chromosomes. Groups like mammals maintain conserved sex chromosome systems, while sex chromosomes in most vertebrate clades aren't conserved across similar evolutionary timescales. One group inferred to have an evolutionarily stable mode of sex determination is Anguimorpha, a clade of charismatic taxa including: monitor lizards, Gila monsters, and crocodile lizards. The common ancestor of extant anguimorphs possessed a ZW system that has been retained across the clade. However, the sex chromosome system in the endangered, monotypic family of crocodile lizards (Shinisauridae) has remained elusive. Here, we analyze genomic data to demonstrate that Shinisaurus has replaced the ancestral anguimorph ZW system on LG7 chromosome with a novel ZW system on LG3. The linkage group LG3 corresponds to chromosome 9 in chicken, and this is the first documented use of this syntenic block as a sex chromosome in amniotes. Additionally, this ~1Mb region harbors approximately 10 genes, including a duplication of the sex-determining transcription factor, Foxl2-critical for the determination and maintenance of sexual differentiation in vertebrates, and thus a putative primary sex determining gene for Shinisaurus.
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Affiliation(s)
- Brendan J. Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
| | - Stuart V. Nielsen
- Department of Biological Sciences, Museum of Life Sciences, Louisiana State University-Shreveport, Shreveport, LA USA
- Florida Museum of Natural History, University of Florida, Gainesville, FL USA
| | - Kathryn A. Sullivan
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
| | - Ashmika Behere
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
| | - Shannon E. Keating
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
| | - Mona van Schingen-Khan
- Federal Agency for Nature Conservation, CITES Scientific Authority, Konstantinstraße 110, 53179 Bonn, Germany
| | - Truong Quang Nguyen
- Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Hanoi 10072, Vietnam
- Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi 10072, Vietnam
| | - Thomas Ziegler
- Cologne Zoo, Riehler Straße 173, 50735 Cologne, Germany
- Department of Biology, Institute of Zoology, University of Cologne, Zülpicher Straße 47b, 50674 Cologne, Germany
| | | | - Melissa A. Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ USA
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ USA
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
- Bell Museum of Natural History, University of Minnesota, St Paul, MN USA
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8
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Pinto BJ, Gamble T, Smith CH, Keating SE, Havird JC, Chiari Y. The revised reference genome of the leopard gecko (Eublepharis macularius) provides insight into the considerations of genome phasing and assembly. J Hered 2023; 114:513-520. [PMID: 36869788 PMCID: PMC10445513 DOI: 10.1093/jhered/esad016] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 02/28/2023] [Indexed: 03/05/2023] Open
Abstract
Genomic resources across squamate reptiles (lizards and snakes) have lagged behind other vertebrate systems and high-quality reference genomes remain scarce. Of the 23 chromosome-scale reference genomes across the order, only 12 of the ~60 squamate families are represented. Within geckos (infraorder Gekkota), a species-rich clade of lizards, chromosome-level genomes are exceptionally sparse representing only two of the seven extant families. Using the latest advances in genome sequencing and assembly methods, we generated one of the highest-quality squamate genomes to date for the leopard gecko, Eublepharis macularius (Eublepharidae). We compared this assembly to the previous, short-read only, E. macularius reference genome published in 2016 and examined potential factors within the assembly influencing contiguity of genome assemblies using PacBio HiFi data. Briefly, the read N50 of the PacBio HiFi reads generated for this study was equal to the contig N50 of the previous E. macularius reference genome at 20.4 kilobases. The HiFi reads were assembled into a total of 132 contigs, which was further scaffolded using HiC data into 75 total sequences representing all 19 chromosomes. We identified 9 of the 19 chromosomal scaffolds were assembled as a near-single contig, whereas the other 10 chromosomes were each scaffolded together from multiple contigs. We qualitatively identified that the percent repeat content within a chromosome broadly affects its assembly contiguity prior to scaffolding. This genome assembly signifies a new age for squamate genomics where high-quality reference genomes rivaling some of the best vertebrate genome assemblies can be generated for a fraction of previous cost estimates. This new E. macularius reference assembly is available on NCBI at JAOPLA010000000.
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Affiliation(s)
- Brendan J Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, USA
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, USA
- Department of Biological Sciences, Marquette University, Milwaukee WI, USA
- Bell Museum of Natural History, University of Minnesota, St Paul, MN, USA
| | - Chase H Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Shannon E Keating
- Department of Biological Sciences, Marquette University, Milwaukee WI, USA
| | - Justin C Havird
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Ylenia Chiari
- Department of Biology, George Mason University, Fairfax, VA, USA
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9
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Pinto BJ, Gamble T, Smith CH, Wilson MA. A lizard is never late: Squamate genomics as a recent catalyst for understanding sex chromosome and microchromosome evolution. J Hered 2023; 114:445-458. [PMID: 37018459 PMCID: PMC10445521 DOI: 10.1093/jhered/esad023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 04/03/2023] [Indexed: 04/07/2023] Open
Abstract
In 2011, the first high-quality genome assembly of a squamate reptile (lizard or snake) was published for the green anole. Dozens of genome assemblies were subsequently published over the next decade, yet these assemblies were largely inadequate for answering fundamental questions regarding genome evolution in squamates due to their lack of contiguity or annotation. As the "genomics age" was beginning to hit its stride in many organismal study systems, progress in squamates was largely stagnant following the publication of the green anole genome. In fact, zero high-quality (chromosome-level) squamate genomes were published between the years 2012 and 2017. However, since 2018, an exponential increase in high-quality genome assemblies has materialized with 24 additional high-quality genomes published for species across the squamate tree of life. As the field of squamate genomics is rapidly evolving, we provide a systematic review from an evolutionary genomics perspective. We collated a near-complete list of publicly available squamate genome assemblies from more than half-a-dozen international and third-party repositories and systematically evaluated them with regard to their overall quality, phylogenetic breadth, and usefulness for continuing to provide accurate and efficient insights into genome evolution across squamate reptiles. This review both highlights and catalogs the currently available genomic resources in squamates and their ability to address broader questions in vertebrates, specifically sex chromosome and microchromosome evolution, while addressing why squamates may have received less historical focus and has caused their progress in genomics to lag behind peer taxa.
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Affiliation(s)
- Brendan J Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, United States
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, United States
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI, United States
- Department of Biological Sciences, Marquette University, Milwaukee, WI, United States
- Bell Museum of Natural History, University of Minnesota, St Paul, MN, United States
| | - Chase H Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, United States
| | - Melissa A Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ, United States
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, United States
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ, United States
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10
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Gable SM, Mendez JM, Bushroe NA, Wilson A, Byars MI, Tollis M. The State of Squamate Genomics: Past, Present, and Future of Genome Research in the Most Speciose Terrestrial Vertebrate Order. Genes (Basel) 2023; 14:1387. [PMID: 37510292 PMCID: PMC10379679 DOI: 10.3390/genes14071387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
Squamates include more than 11,000 extant species of lizards, snakes, and amphisbaenians, and display a dazzling diversity of phenotypes across their over 200-million-year evolutionary history on Earth. Here, we introduce and define squamates (Order Squamata) and review the history and promise of genomic investigations into the patterns and processes governing squamate evolution, given recent technological advances in DNA sequencing, genome assembly, and evolutionary analysis. We survey the most recently available whole genome assemblies for squamates, including the taxonomic distribution of available squamate genomes, and assess their quality metrics and usefulness for research. We then focus on disagreements in squamate phylogenetic inference, how methods of high-throughput phylogenomics affect these inferences, and demonstrate the promise of whole genomes to settle or sustain persistent phylogenetic arguments for squamates. We review the role transposable elements play in vertebrate evolution, methods of transposable element annotation and analysis, and further demonstrate that through the understanding of the diversity, abundance, and activity of transposable elements in squamate genomes, squamates can be an ideal model for the evolution of genome size and structure in vertebrates. We discuss how squamate genomes can contribute to other areas of biological research such as venom systems, studies of phenotypic evolution, and sex determination. Because they represent more than 30% of the living species of amniote, squamates deserve a genome consortium on par with recent efforts for other amniotes (i.e., mammals and birds) that aim to sequence most of the extant families in a clade.
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Affiliation(s)
- Simone M Gable
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Jasmine M Mendez
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Nicholas A Bushroe
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Adam Wilson
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Michael I Byars
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Marc Tollis
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ 86011, USA
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11
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Webster TH, Vannan A, Pinto BJ, Denbrock G, Morales M, Dolby GA, Fiddes IT, DeNardo DF, Wilson MA. Incomplete dosage balance and dosage compensation in the ZZ/ZW Gila monster ( Heloderma suspectum) revealed by de novo genome assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.26.538436. [PMID: 37163099 PMCID: PMC10168389 DOI: 10.1101/2023.04.26.538436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Reptiles exhibit a variety of modes of sex determination, including both temperature-dependent and genetic mechanisms. Among those species with genetic sex determination, sex chromosomes of varying heterogamety (XX/XY and ZZ/ZW) have been observed with different degrees of differentiation. Karyotype studies have demonstrated that Gila monsters (Heloderma suspectum) have ZZ/ZW sex determination and this system is likely homologous to the ZZ/ZW system in the Komodo dragon (Varanus komodoensis), but little else is known about their sex chromosomes. Here, we report the assembly and analysis of the Gila monster genome. We generated a de novo draft genome assembly for a male using 10X Genomics technology. We further generated and analyzed short-read whole genome sequencing and whole transcriptome sequencing data for three males and three females. By comparing female and male genomic data, we identified four putative Z-chromosome scaffolds. These putative Z-chromosome scaffolds are homologous to Z-linked scaffolds identified in the Komodo dragon. Further, by analyzing RNAseq data, we observed evidence of incomplete dosage compensation between the Gila monster Z chromosome and autosomes and a lack of balance in Z-linked expression between the sexes. In particular, we observe lower expression of the Z in females (ZW) than males (ZZ) on a global basis, though we find evidence suggesting local gene-by-gene compensation. This pattern has been observed in most other ZZ/ZW systems studied to date and may represent a general pattern for female heterogamety in vertebrates.
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Affiliation(s)
- Timothy H. Webster
- Department of Anthropology, University of Utah, Salt Lake City, UT
- School of Life Sciences, Arizona State University, Tempe, AZ
| | - Annika Vannan
- School of Life Sciences, Arizona State University, Tempe, AZ
| | - Brendan J. Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
| | - Grant Denbrock
- School of Life Sciences, Arizona State University, Tempe, AZ
| | - Matheo Morales
- School of Life Sciences, Arizona State University, Tempe, AZ
- Department of Genetics, Yale University, New Haven, CT
| | - Greer A. Dolby
- School of Life Sciences, Arizona State University, Tempe, AZ
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ
| | | | - Dale F. DeNardo
- School of Life Sciences, Arizona State University, Tempe, AZ
| | - Melissa A. Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ
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12
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Pinto BJ, Gamble T, Smith CH, Wilson MA. A lizard is never late: squamate genomics as a recent catalyst for understanding sex chromosome and microchromosome evolution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.524006. [PMID: 37034614 PMCID: PMC10081179 DOI: 10.1101/2023.01.20.524006] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
In 2011, the first high-quality genome assembly of a squamate reptile (lizard or snake) was published for the green anole. Dozens of genome assemblies were subsequently published over the next decade, yet these assemblies were largely inadequate for answering fundamental questions regarding genome evolution in squamates due to their lack of contiguity or annotation. As the "genomics age" was beginning to hit its stride in many organismal study systems, progress in squamates was largely stagnant following the publication of the green anole genome. In fact, zero high-quality (chromosome-level) squamate genomes were published between the years 2012-2017. However, since 2018, an exponential increase in high-quality genome assemblies has materialized with 24 additional high-quality genomes published for species across the squamate tree of life. As the field of squamate genomics is rapidly evolving, we provide a systematic review from an evolutionary genomics perspective. We collated a near-complete list of publicly available squamate genome assemblies from more than half-a-dozen international and third-party repositories and systematically evaluated them with regard to their overall quality, phylogenetic breadth, and usefulness for continuing to provide accurate and efficient insights into genome evolution across squamate reptiles. This review both highlights and catalogs the currently available genomic resources in squamates and their ability to address broader questions in vertebrates, specifically sex chromosome and microchromosome evolution, while addressing why squamates may have received less historical focus and has caused their progress in genomics to lag behind peer taxa.
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Affiliation(s)
- Brendan J Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
- Bell Museum of Natural History, University of Minnesota, St Paul, MN USA
| | - Chase H Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Melissa A Wilson
- School of Life Sciences, Arizona State University, Tempe, AZ USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ USA
- Center for Mechanisms of Evolution, Biodesign Institute, Tempe, AZ USA
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Dodge TO, Farquharson KA, Ford C, Cavanagh L, Schubert K, Schumer M, Belov K, Hogg CJ. Genomes of two Extinct-in-the-Wild reptiles from Christmas Island reveal distinct evolutionary histories and conservation insights. Mol Ecol Resour 2023. [PMID: 36872490 DOI: 10.1111/1755-0998.13780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 02/16/2023] [Accepted: 03/02/2023] [Indexed: 03/07/2023]
Abstract
Genomics can play important roles in biodiversity conservation, especially for Extinct-in-the-Wild species where genetic factors greatly influence risk of total extinction and probability of successful reintroductions. The Christmas Island blue-tailed skink (Cryptoblepharus egeriae) and Lister's gecko (Lepidodactylus listeri) are two endemic reptile species that went extinct in the wild shortly after the introduction of a predatory snake. After a decade of management, captive populations have expanded from 66 skinks and 43 geckos to several thousand individuals; however, little is known about patterns of genetic variation in these species. Here, we use PacBio HiFi long-read and Hi-C sequencing to generate highly contiguous reference genomes for both reptiles, including the XY chromosome pair in the skink. We then analyse patterns of genetic diversity to infer ancient demography and more recent histories of inbreeding. We observe high genome-wide heterozygosity in the skink (0.007 heterozygous sites per base-pair) and gecko (0.005), consistent with large historical population sizes. However, nearly 10% of the blue-tailed skink reference genome falls within long (>1 Mb) runs of homozygosity (ROH), resulting in homozygosity at all major histocompatibility complex (MHC) loci. In contrast, we detect a single ROH in Lister's gecko. We infer from the ROH lengths that related skinks may have established the captive populations. Despite a shared recent extinction in the wild, our results suggest important differences in these species' histories and implications for management. We show how reference genomes can contribute evolutionary and conservation insights, and we provide resources for future population-level and comparative genomic studies in reptiles.
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Affiliation(s)
- Tristram O Dodge
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, New South Wales, Australia
- Department of Biology, Stanford University, Stanford, California, USA
- Australian-American Fulbright Commission, Deakin, Australian Capital Territory, Australia
| | - Katherine A Farquharson
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Claire Ford
- Taronga Conservation Society Australia, Mosman, New South Wales, Australia
| | - Lisa Cavanagh
- Taronga Conservation Society Australia, Mosman, New South Wales, Australia
| | | | - Molly Schumer
- Department of Biology, Stanford University, Stanford, California, USA
| | - Katherine Belov
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, New South Wales, Australia
| | - Carolyn J Hogg
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Sydney, Sydney, New South Wales, Australia
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14
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Pinto BJ, Gamble T, Smith CH, Keating SE, Havird JC, Chiari Y. The revised reference genome of the leopard gecko ( Eublepharis macularius ) provides insight into the considerations of genome phasing and assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.20.523807. [PMID: 36712019 PMCID: PMC9882329 DOI: 10.1101/2023.01.20.523807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Genomic resources across squamate reptiles (lizards and snakes) have lagged behind other vertebrate systems and high-quality reference genomes remain scarce. Of the 23 chromosome-scale reference genomes across the order, only 12 of the ~60 squamate families are represented. Within geckos (infraorder Gekkota), a species-rich clade of lizards, chromosome-level genomes are exceptionally sparse representing only two of the seven extant families. Using the latest advances in genome sequencing and assembly methods, we generated one of the highest quality squamate genomes to date for the leopard gecko, Eublepharis macularius (Eublepharidae). We compared this assembly to the previous, short-read only, E. macularius reference genome published in 2016 and examined potential factors within the assembly influencing contiguity of genome assemblies using PacBio HiFi data. Briefly, the read N50 of the PacBio HiFi reads generated for this study was equal to the contig N50 of the previous E. macularius reference genome at 20.4 kilobases. The HiFi reads were assembled into a total of 132 contigs, which was further scaffolded using HiC data into 75 total sequences representing all 19 chromosomes. We identified that 9 of the 19 chromosomes were assembled as single contigs, while the other 10 chromosomes were each scaffolded together from two or more contigs. We qualitatively identified that percent repeat content within a chromosome broadly affects its assembly contiguity prior to scaffolding. This genome assembly signifies a new age for squamate genomics where high-quality reference genomes rivaling some of the best vertebrate genome assemblies can be generated for a fraction previous cost estimates. This new E. macularius reference assembly is available on NCBI at JAOPLA010000000. The genome version and its associated annotations are also available via this Figshare repository https://doi.org/10.6084/m9.figshare.20069273 .
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Affiliation(s)
- Brendan J. Pinto
- School of Life Sciences, Arizona State University, Tempe, AZ USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ USA
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
| | - Tony Gamble
- Department of Zoology, Milwaukee Public Museum, Milwaukee, WI USA
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
- Bell Museum of Natural History, University of Minnesota, St Paul, MN USA
| | - Chase H. Smith
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Shannon E. Keating
- Department of Biological Sciences, Marquette University, Milwaukee WI USA
| | - Justin C. Havird
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
| | - Ylenia Chiari
- Department of Biology, George Mason University, Fairfax, VA, USA
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15
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Leitão HG, Diedericks G, Broeckhoven C, Baeckens S, Svardal H. Chromosome-Level Genome Assembly of the Cape Cliff Lizard (Hemicordylus capensis). Genome Biol Evol 2023; 15:6980485. [PMID: 36624992 PMCID: PMC9907493 DOI: 10.1093/gbe/evad001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/30/2022] [Accepted: 01/06/2023] [Indexed: 01/11/2023] Open
Abstract
Squamates represent a highly diverse and species-rich vertebrate group that is remarkably understudied from a genomic perspective. A scarcity of genomic data is particularly evident for scincomorph lizards, which encompass over 10% of all living squamates, and for which high-quality genomic resources are currently lacking. To address this knowledge gap, we present the first chromosome-level reference genome for this group, generated from a male Cape cliff lizard (Hemicordylus capensis), using highly accurate PacBio HiFi long-read sequencing data, long-range Omni-C chromosomal conformation capture data and transcriptomic data for annotation. The rHemCap1.1 genome assembly spans 2.29 Gb, with a scaffold N50 of 359.65 Mb, and includes 25,300 protein-coding genes, with a BUSCO completeness score of 95.5% (sauropsida_odb10). We have generated the most contiguous and complete chromosome-level squamate reference genome assembly publicly available to date. Furthermore, we used short-read resequencing of 35 males and females and applied a differential coverage approach to infer the sex-determination system of the species, which was previously unknown. Our results suggest this species has XX/XY sex chromosomes, representing the first evidence of sex determination in the family Cordylidae. This reference genome will help to establish this species as an evolutionary model for studying variation in body armor, a key trait in cordylids and other squamate groups. Lastly, this is the first squamate reference genome from a continental African species and, as such, represents a valuable resource not only for further evolutionary research in cordylids but also in closely related groups.
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Affiliation(s)
| | - Genevieve Diedericks
- Department of Biology, University of Antwerp, 2610 Antwerp, Belgium,Department of Botany and Zoology, Stellenbosch University, Matieland Stellenbosch, South Africa
| | | | - Simon Baeckens
- Department of Biology, University of Antwerp, 2610 Antwerp, Belgium,Department of Biology, Ghent University, 9000 Ghent, Belgium
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Pensabene E, Yurchenko A, Kratochvíl L, Rovatsos M. Madagascar Leaf-Tail Geckos ( Uroplatus spp.) Share Independently Evolved Differentiated ZZ/ZW Sex Chromosomes. Cells 2023; 12:cells12020260. [PMID: 36672195 PMCID: PMC9856856 DOI: 10.3390/cells12020260] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 01/10/2023] Open
Abstract
Geckos are an excellent group to study the evolution of sex determination, as they possess a remarkable variability ranging from a complete absence of sex chromosomes to highly differentiated sex chromosomes. We explored sex determination in the Madagascar leaf-tail geckos of the genus Uroplatus. The cytogenetic analyses revealed highly heterochromatic W chromosomes in all three examined species (Uroplatus henkeli, U. alluaudi, U. sikorae). The comparative gene coverage analysis between sexes in U. henkeli uncovered an extensive Z-specific region, with a gene content shared with the chicken chromosomes 8, 20, 26 and 28. The genomic region homologous to chicken chromosome 28 has been independently co-opted for the role of sex chromosomes in several vertebrate lineages, including monitors, beaded lizards and monotremes, perhaps because it contains the amh gene, whose homologs were repeatedly recruited as a sex-determining locus. We demonstrate that all tested species of leaf-tail geckos share homologous sex chromosomes despite the differences in shape and size of their W chromosomes, which are not homologous to the sex chromosomes of other closely related genera. The rather old (at least 40 million years), highly differentiated sex chromosomes of Uroplatus geckos can serve as a great system to study the convergence of sex chromosomes evolved from the same genomic region.
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17
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Kostmann A, Kratochvíl L, Rovatsos M. ZZ/ZW Sex Chromosomes in the Madagascar Girdled Lizard, Zonosaurus madagascariensis (Squamata: Gerrhosauridae). Genes (Basel) 2022; 14:genes14010099. [PMID: 36672840 PMCID: PMC9859402 DOI: 10.3390/genes14010099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 12/23/2022] [Accepted: 12/26/2022] [Indexed: 12/31/2022] Open
Abstract
Scincoidea, the reptilian clade that includes girdled lizards, night lizards, plated lizards and skinks, are considered as a lineage with diversity in sex-determining systems. Recently, the hypothesis on the variability in sex determination in skinks and even more the absence of sex chromosomes in some of them has been rivalling. Homologous, evolutionary stable XX/XY sex chromosomes were documented to be widespread across skinks. However, sex determination in the other scincoidean families is highly understudied. ZZ/ZW sex chromosomes have been identified only in night lizards and a single species of plated lizards. It seems that although there are different sex chromosome systems among scincoidean lineages, they share one common trait: they are mostly poorly differentiated and often undetectable by cytogenetic methods. Here, we report one of the exceptions, demonstrating for the first time ZZ/ZW sex chromosomes in the plated lizard Zonosaurus madagascariensis. Its sex chromosomes are morphologically similar, but the W is clearly detectable by comparative genomic hybridization (CGH), suggesting that the Z and W chromosomes highly differ in sequence content. Our findings confirm the presence of female heterogamety in plated lizards and provides novel insights to expand our understanding of sex chromosome evolution in scincoidean lizards.
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