Reptile Evolution and Genetics - Special Issue Dedicated to the Memory of Prof. Teresa Capriglione

A special issue of Animals (ISSN 2076-2615). This special issue belongs to the section "Herpetology".

Deadline for manuscript submissions: closed (15 December 2022) | Viewed by 34938

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Via Brecce Bianche, IT-60131 Ancona, Italy
Interests: evolutionary biology; vertebrate genome; cytogenetics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue of Animals on “Reptile Evolution and Genetics” is dedicated to the memory of Prof. Teresa Capriglione (1959-2020), the outstanding Italian researcher in the field of vertebrate evolutionary cytogenetics and genomics who unfortunately passed away in July 2020.

Teresa Capriglione was a pioneering researcher in the study of the genome composition and evolution of non-mammalian vertebrates.

Her main field of research was the study of the presence and evolution of highly repetitive DNAs and transposons in reptiles and fishes, for which she was considered one of the most prominent experts in the world. In this regard, the results she obtained in her studies on the role of the highly repetitive DNA in sex determination and the differentiation of sex chromosomes were very important. In addition, her study on gene expression during the development of reptiles and amphibians also produced relevant findings.

Teresa Cariglione published more than 100 excellent papers in outstanding scientific journals.

The death of Teresa Capriglione was a great loss for the international community and for all researchers in the field of genomics and evolutionary biology. However, her memory will be alive forever in the hearts of her many colleagues and friends.

One basal event of biological evolution is the dialectics between the variability at the genetic, genomic and chromosomic levels and natural selection.

In this regard, reptiles are a very interesting model both for the key position they occupy in the phylogeny of terrestrial vertebrates and because they have experienced several relevant evolutionary events such as the transition from environmental and genetic sex determination, oviparous and viviparous development modes, parthenogenetic reproduction and various mechanisms of thermoregulation.

This Special Issue of Animals presents an up-to-date picture of studies on the role that genetic, genomic and chromosomic mechanisms play in reptile evolution and in special aspects such as sex determination, thermoregulation, oviparous and viviparous development and parthenogenesis.

Prof. Dr. Ettore Olmo
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Animals is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • genetics
  • genome
  • chromosomes
  • evolution
  • sex determination
  • development
  • parthenogenesis

Published Papers (13 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Editorial

Jump to: Research, Review

6 pages, 202 KiB  
Editorial
Reptile Evolution and Genetics: An Overview
by Ettore Olmo
Animals 2023, 13(12), 1924; https://doi.org/10.3390/ani13121924 - 08 Jun 2023
Viewed by 1000
Abstract
The study of evolution has been indissolubly linked to the study of heredity since its inception [1]. [...] Full article

Research

Jump to: Editorial, Review

17 pages, 4202 KiB  
Article
Global Terrapin Character-Based DNA Barcodes: Assessment of the Mitochondrial COI Gene and Conservation Status Revealed a Putative Cryptic Species
by Mohd Hairul Mohd Salleh, Yuzine Esa and Rozihan Mohamed
Animals 2023, 13(11), 1720; https://doi.org/10.3390/ani13111720 - 23 May 2023
Cited by 1 | Viewed by 1126
Abstract
Technological and analytical advances to study evolutionary biology, ecology, and conservation of the Southern River Terrapin (Batagur affinis ssp.) are realised through molecular approaches, including DNA barcoding. We evaluated the use of COI DNA barcodes in Malaysia’s Southern River Terrapin population to [...] Read more.
Technological and analytical advances to study evolutionary biology, ecology, and conservation of the Southern River Terrapin (Batagur affinis ssp.) are realised through molecular approaches, including DNA barcoding. We evaluated the use of COI DNA barcodes in Malaysia’s Southern River Terrapin population to better understand the species’ genetic divergence and other genetic characteristics. We evaluated 26 sequences, including four from field specimens of Southern River Terrapins obtained in Bota Kanan, Perak, Malaysia, and Kuala Berang, Terengganu, Malaysia, as well as 22 sequences from global terrapins previously included in the Barcode of Life Database (BOLD) Systems and GenBank. The species are divided into three families: eight Geoemydidae species (18%), three Emydidae species (6%), and one Pelomedusidae species (2%). The IUCN Red List assigned the 12 species of terrapins sampled for this study to the classifications of critically endangered (CR) for 25% of the samples and endangered (EN) for 8% of the samples. With new haplotypes from the world’s terrapins, 16 haplotypes were found. The intraspecific distance values between the COI gene sequences were calculated using the K2P model, which indicated a potential cryptic species between the Northern River Terrapin (Batagur baska) and Southern River Terrapin (Batagur affinis affinis). The Bayesian analysis of the phylogenetic tree also showed both species in the same lineage. The BLASTn search resulted in 100% of the same species of B. affinis as B. baska. The Jalview alignment visualised almost identical sequences between both species. The Southern River Terrapin (B. affinis affinis) from the west coast of Peninsular Malaysia was found to share the same haplotype (Hap_1) as the Northern River Terrapin from India. However, B. affinis edwardmolli from the east coast of Peninsular Malaysia formed Hap_16. The COI analysis found new haplotypes and showed that DNA barcodes are an excellent way to measure the diversity of a population. Full article
Show Figures

Figure 1

11 pages, 1952 KiB  
Article
Conservation of Major Satellite DNAs in Snake Heterochromatin
by Artem Lisachov, Alexander Rumyantsev, Dmitry Prokopov, Malcolm Ferguson-Smith and Vladimir Trifonov
Animals 2023, 13(3), 334; https://doi.org/10.3390/ani13030334 - 17 Jan 2023
Cited by 4 | Viewed by 1631
Abstract
Repetitive DNA sequences constitute a sizeable portion of animal genomes, and tandemly organized satellite DNAs are a major part of them. They are usually located in constitutive heterochromatin clusters in or near the centromeres or telomeres, and less frequently in the interstitial parts [...] Read more.
Repetitive DNA sequences constitute a sizeable portion of animal genomes, and tandemly organized satellite DNAs are a major part of them. They are usually located in constitutive heterochromatin clusters in or near the centromeres or telomeres, and less frequently in the interstitial parts of chromosome arms. They are also frequently accumulated in sex chromosomes. The function of these clusters is to sustain the architecture of the chromosomes and the nucleus, and to regulate chromosome behavior during mitosis and meiosis. The study of satellite DNA diversity is important for understanding sex chromosome evolution, interspecific hybridization, and speciation. In this work, we identified four satellite DNA families in the genomes of two snakes from different families: Daboia russelii (Viperidae) and Pantherophis guttatus (Colubridae) and determine their chromosomal localization. We found that one family is localized in the centromeres of both species, whereas the others form clusters in certain chromosomes or subsets of chromosomes. BLAST with snake genome assemblies showed the conservation of such clusters, as well as a subtle presence of the satellites in the interspersed manner outside the clusters. Overall, our results show high conservation of satellite DNA in snakes and confirm the “library” model of satellite DNA evolution. Full article
Show Figures

Figure 1

14 pages, 905 KiB  
Article
A Cautionary Tale of Sexing by Methylation: Hybrid Bisulfite-Conversion Sequencing of Immunoprecipitated Methylated DNA in Chrysemys picta Turtles with Temperature-Dependent Sex Determination Reveals Contrasting Patterns of Somatic and Gonadal Methylation, but No Unobtrusive Sex Diagnostic
by Beatriz A. Mizoguchi and Nicole Valenzuela
Animals 2023, 13(1), 117; https://doi.org/10.3390/ani13010117 - 28 Dec 2022
Cited by 2 | Viewed by 1489
Abstract
Background: The gonads of Chrysemys picta, a turtle with temperature-dependent sex determination (TSD), exhibit differential DNA methylation between males and females, but whether the same is true in somatic tissues remains unknown. Such differential DNA methylation in the soma would provide [...] Read more.
Background: The gonads of Chrysemys picta, a turtle with temperature-dependent sex determination (TSD), exhibit differential DNA methylation between males and females, but whether the same is true in somatic tissues remains unknown. Such differential DNA methylation in the soma would provide a non-lethal sex diagnostic for TSD turtle hatchings who lack visually detectable sexual dimorphism when young. Methods: Here, we tested multiple approaches to study DNA methylation in tail clips of Chrysemys picta hatchlings, to identify differentially methylated candidate regions/sites that could serve as molecular sex markers To detect global differential methylation in the tails we used methylation-sensitive ELISA, and to test for differential local methylation we developed a novel hybrid method by sequencing immunoprecipitated and bisulfite converted DNA (MeDIP-BS-seq) followed by PCR validation of candidate regions/sites after digestion with a methylation-sensitive restriction enzyme. Results: We detected no global differences in methylation between males and females via ELISA. While we detected inter-individual variation in DNA methylation in the tails, this variation was not sexually dimorphic, in contrast with hatchling gonads. Conclusions: Results highlight that differential DNA methylation is tissue-specific and plays a key role in gonadal formation (primary sexual development) and maintenance post-hatching, but not in the somatic tail tissue. Full article
Show Figures

Figure 1

16 pages, 3393 KiB  
Article
Cytogenetic Analysis of the Bimodal Karyotype of the Common European Adder, Vipera berus (Viperidae)
by Victor Spangenberg, Ilya Redekop, Sergey A. Simanovsky and Oxana Kolomiets
Animals 2022, 12(24), 3563; https://doi.org/10.3390/ani12243563 - 16 Dec 2022
Cited by 2 | Viewed by 2190
Abstract
Vipera berus is the species with the largest range of snakes on Earth and one of the largest among reptiles in general. It is also the only snake species found in the Arctic Circle. Vipera berus is the most involved species of the [...] Read more.
Vipera berus is the species with the largest range of snakes on Earth and one of the largest among reptiles in general. It is also the only snake species found in the Arctic Circle. Vipera berus is the most involved species of the genus Vipera in the process of interspecific hybridization in nature. The taxonomy of the genus Vipera is based on molecular markers and morphology and requires clarification using SC-karyotyping. This work is a detailed comparative study of the somatic and meiotic karyotypes of V. berus, with special attention to DNA and protein markers associated with synaptonemal complexes. The karyotype of V. berus is a remarkable example of a bimodal karyotype containing both 16 large macrochromosomes and 20 microchromosomes. We traced the stages of the asynchronous assembly of both types of bivalents. The number of crossing-over sites per pachytene nucleus, the localization of the nucleolar organizer, and the unique heterochromatin block on the autosomal bivalent 6—an important marker—were determined. Our results show that the average number of crossing-over sites per pachytene nucleus is 49.5, and the number of MLH1 sites per bivalent 1 reached 11, which is comparable to several species of agamas. Full article
Show Figures

Figure 1

17 pages, 3174 KiB  
Article
Chromosome Evolution of the Liolaemus monticola (Liolaemidae) Complex: Chromosomal and Molecular Aspects
by Madeleine Lamborot, Carmen Gloria Ossa, Nicolás Aravena-Muñoz, David Véliz and Raúl Araya-Donoso
Animals 2022, 12(23), 3372; https://doi.org/10.3390/ani12233372 - 30 Nov 2022
Cited by 1 | Viewed by 1168
Abstract
Chromosomal rearrangements can directly influence population differentiation and speciation. The Liolaemus monticola complex in Chile is a unique model consisting of several chromosome races arranged in a latitudinal sequence of increasing karyotype complexity from south to north. Here, we compared chromosomal and mitochondrial [...] Read more.
Chromosomal rearrangements can directly influence population differentiation and speciation. The Liolaemus monticola complex in Chile is a unique model consisting of several chromosome races arranged in a latitudinal sequence of increasing karyotype complexity from south to north. Here, we compared chromosomal and mitochondrial cytochrome b data from 15 localities across the northern geographic distribution of L. monticola. We expanded the distribution of the previously described Multiple Fissions race (re-described as MF2), in the Coastal range between the Aconcagua River and the Petorca River, and described a new Multiple Fissions 1 (MF1) race in the Andean range. Both races present centric fissions in pairs 1 and 2, as well as a pericentric inversion in one fission product of pair 2 that changes the NOR position. Additionally, we detected a new chromosomal race north of the Petorca River, the Northern Modified 2 (NM2) race, which is polymorphic for novel centric fissions in pairs 3 and 4. Our results increase the number of chromosomal races in L. monticola to seven, suggesting a complex evolutionary history of chromosomal rearrangements, population isolation by barriers, and hybridization. These results show the relevant role of chromosome mutations in evolution, especially for highly speciose groups such as Liolaemus lizards. Full article
Show Figures

Figure 1

11 pages, 1057 KiB  
Article
Temperature Incubation Influences Gonadal Gene Expression during Leopard Gecko Development
by Maria Michela Pallotta, Chiara Fogliano and Rosa Carotenuto
Animals 2022, 12(22), 3186; https://doi.org/10.3390/ani12223186 - 17 Nov 2022
Cited by 2 | Viewed by 1462
Abstract
During development, sexual differentiation results in physiological, anatomical and metabolic differences that implicate not only the gonads but also other body structures. Sex in Leopard geckos is determined by egg incubation temperature. Based on the premise that the developmental decision of gender does [...] Read more.
During development, sexual differentiation results in physiological, anatomical and metabolic differences that implicate not only the gonads but also other body structures. Sex in Leopard geckos is determined by egg incubation temperature. Based on the premise that the developmental decision of gender does not depend on a single gene, we performed an analysis on E. macularius to gain insights into the genes that may be involved in gonads’ sexual differentiation during the thermosensitive period. All the genes were identified as differentially expressed at stage 30 during the labile phase of sex differentiation. In this way, the expression of genes known to be involved in gonadal sexual differentiation, such as WNT4, SOX9, DMRT1, Erα, Erβ, GnRH, P450 aromatase, PRLand PRL-R, was investigated. Other genes putatively involved in sex differentiation were sought by differential display. Our findings indicate that embryo exposure to a sex-determining temperature induces differential expression of several genes that are involved not only in gonadal differentiation, but also in several biological pathways (ALDOC, FREM1, BBIP1, CA5A, NADH5, L1 non-LTR retrotransposons, PKM). Our data perfectly fit within the new studies conducted in developmental biology, which indicate that in the developing embryo, in addition to gonadal differentiation, sex-specific tissue and metabolic polarization take place in all organisms. Full article
Show Figures

Figure 1

12 pages, 2205 KiB  
Article
First Insights on the Karyotype Diversification of the Endemic Malagasy Leaf-Toed Geckos (Squamata: Gekkonidae: Uroplatus)
by Marcello Mezzasalma, Elvira Brunelli, Gaetano Odierna and Fabio Maria Guarino
Animals 2022, 12(16), 2054; https://doi.org/10.3390/ani12162054 - 12 Aug 2022
Cited by 8 | Viewed by 1524
Abstract
We provide here the first karyotype description of eight Uroplatus species and a characterization of their chromosomal diversity. We performed a molecular taxonomic assessment of several Uroplatus samples using the mitochondrial 12S marker and a comparative cytogenetic analysis with standard karyotyping, silver staining [...] Read more.
We provide here the first karyotype description of eight Uroplatus species and a characterization of their chromosomal diversity. We performed a molecular taxonomic assessment of several Uroplatus samples using the mitochondrial 12S marker and a comparative cytogenetic analysis with standard karyotyping, silver staining (Ag-NOR) and sequential C-banding + Giemsa, +Chromomycin A3 (CMA3), +4′,6-diamidino-2-phenylindole (DAPI). We found chromosomal variability in terms of chromosome number (2n = 34–38), heterochromatin composition and number and localization of loci or Nucleolar Organizer Regions (NORs) (alternatively on the 2nd, 6th, 10th or 16th pair). Chromosome morphology is almost constant, with karyotypes composed of acrocentric chromosomes, gradually decreasing in length. C-banding evidenced a general low content of heterochromatin, mostly localized on pericentromeric and telomeric regions. Centromeric bands varied among the species studied, resulting in CMA3 positive and DAPI negative or positive to both fluorochromes. We also provide evidence of a first putative heteromorphic sex chromosome system in the genus. In fact, in U. alluaudi the 10th pair was highly heteromorphic, with a metacentric, largely heterochromatic W chromosome, which was much bigger than the Z. We propose an evolutionary scenario of chromosome reduction from 2n = 38 to 2n = 34, by means of translocations of microchromosomes on larger chromosomes (often involving the NOR-bearing microchromosomes). Adding our data to those available from the literature, we show that similar processes characterized the evolutionary radiation of a larger gecko clade. Finally, we hypothesize that sex chromosome diversification occurred independently in different genera. Full article
Show Figures

Figure 1

13 pages, 1573 KiB  
Article
Concerted and Independent Evolution of Control Regions 1 and 2 of Water Monitor Lizards (Varanus salvator macromaculatus) and Different Phylogenetic Informative Markers
by Watcharaporn Thapana, Nattakan Ariyaraphong, Parinya Wongtienchai, Nararat Laopichienpong, Worapong Singchat, Thitipong Panthum, Syed Farhan Ahmad, Ekaphan Kraichak, Narongrit Muangmai, Prateep Duengkae and Kornsorn Srikulnath
Animals 2022, 12(2), 148; https://doi.org/10.3390/ani12020148 - 08 Jan 2022
Cited by 2 | Viewed by 2573
Abstract
Duplicate control regions (CRs) have been observed in the mitochondrial genomes (mitogenomes) of most varanids. Duplicate CRs have evolved in either concerted or independent evolution in vertebrates, but whether an evolutionary pattern exists in varanids remains unknown. Therefore, we conducted this study to [...] Read more.
Duplicate control regions (CRs) have been observed in the mitochondrial genomes (mitogenomes) of most varanids. Duplicate CRs have evolved in either concerted or independent evolution in vertebrates, but whether an evolutionary pattern exists in varanids remains unknown. Therefore, we conducted this study to analyze the evolutionary patterns and phylogenetic utilities of duplicate CRs in 72 individuals of Varanus salvator macromaculatus and other varanids. Sequence analyses and phylogenetic relationships revealed that divergence between orthologous copies from different individuals was lower than in paralogous copies from the same individual, suggesting an independent evolution of the two CRs. Distinct trees and recombination testing derived from CR1 and CR2 suggested that recombination events occurred between CRs during the evolutionary process. A comparison of substitution saturation showed the potential of CR2 as a phylogenetic marker. By contrast, duplicate CRs of the four examined varanids had similar sequences within species, suggesting typical characteristics of concerted evolution. The results provide a better understanding of the molecular evolutionary processes related to the mitogenomes of the varanid lineage. Full article
Show Figures

Figure 1

Review

Jump to: Editorial, Research

35 pages, 3599 KiB  
Review
Past, Present, and Future of Naturally Occurring Antimicrobials Related to Snake Venoms
by Nancy Oguiura, Leonardo Sanches, Priscila V. Duarte, Marcos A. Sulca-López and Maria Terêsa Machini
Animals 2023, 13(4), 744; https://doi.org/10.3390/ani13040744 - 19 Feb 2023
Cited by 5 | Viewed by 2673
Abstract
This review focuses on proteins and peptides with antimicrobial activity because these biopolymers can be useful in the fight against infectious diseases and to overcome the critical problem of microbial resistance to antibiotics. In fact, snakes show the highest diversification among reptiles, surviving [...] Read more.
This review focuses on proteins and peptides with antimicrobial activity because these biopolymers can be useful in the fight against infectious diseases and to overcome the critical problem of microbial resistance to antibiotics. In fact, snakes show the highest diversification among reptiles, surviving in various environments; their innate immunity is similar to mammals and the response of their plasma to bacteria and fungi has been explored mainly in ecological studies. Snake venoms are a rich source of components that have a variety of biological functions. Among them are proteins like lectins, metalloproteinases, serine proteinases, L-amino acid oxidases, phospholipases type A2, cysteine-rich secretory proteins, as well as many oligopeptides, such as waprins, cardiotoxins, cathelicidins, and β-defensins. In vitro, these biomolecules were shown to be active against bacteria, fungi, parasites, and viruses that are pathogenic to humans. Not only cathelicidins, but all other proteins and oligopeptides from snake venom have been proteolyzed to provide short antimicrobial peptides, or for use as templates for developing a variety of short unnatural sequences based on their structures. In addition to organizing and discussing an expressive amount of information, this review also describes new β-defensin sequences of Sistrurus miliarius that can lead to novel peptide-based antimicrobial agents, using a multidisciplinary approach that includes sequence phylogeny. Full article
Show Figures

Figure 1

33 pages, 2738 KiB  
Review
Genome Evolution and the Future of Phylogenomics of Non-Avian Reptiles
by Daren C. Card, W. Bryan Jennings and Scott V. Edwards
Animals 2023, 13(3), 471; https://doi.org/10.3390/ani13030471 - 29 Jan 2023
Cited by 7 | Viewed by 7334
Abstract
Non-avian reptiles comprise a large proportion of amniote vertebrate diversity, with squamate reptiles—lizards and snakes—recently overtaking birds as the most species-rich tetrapod radiation. Despite displaying an extraordinary diversity of phenotypic and genomic traits, genomic resources in non-avian reptiles have accumulated more slowly than [...] Read more.
Non-avian reptiles comprise a large proportion of amniote vertebrate diversity, with squamate reptiles—lizards and snakes—recently overtaking birds as the most species-rich tetrapod radiation. Despite displaying an extraordinary diversity of phenotypic and genomic traits, genomic resources in non-avian reptiles have accumulated more slowly than they have in mammals and birds, the remaining amniotes. Here we review the remarkable natural history of non-avian reptiles, with a focus on the physical traits, genomic characteristics, and sequence compositional patterns that comprise key axes of variation across amniotes. We argue that the high evolutionary diversity of non-avian reptiles can fuel a new generation of whole-genome phylogenomic analyses. A survey of phylogenetic investigations in non-avian reptiles shows that sequence capture-based approaches are the most commonly used, with studies of markers known as ultraconserved elements (UCEs) especially well represented. However, many other types of markers exist and are increasingly being mined from genome assemblies in silico, including some with greater information potential than UCEs for certain investigations. We discuss the importance of high-quality genomic resources and methods for bioinformatically extracting a range of marker sets from genome assemblies. Finally, we encourage herpetologists working in genomics, genetics, evolutionary biology, and other fields to work collectively towards building genomic resources for non-avian reptiles, especially squamates, that rival those already in place for mammals and birds. Overall, the development of this cross-amniote phylogenomic tree of life will contribute to illuminate interesting dimensions of biodiversity across non-avian reptiles and broader amniotes. Full article
Show Figures

Graphical abstract

12 pages, 1038 KiB  
Review
Dinosaurs: Comparative Cytogenomics of Their Reptile Cousins and Avian Descendants
by Darren K. Griffin, Denis M. Larkin, Rebecca E. O’Connor and Michael N. Romanov
Animals 2023, 13(1), 106; https://doi.org/10.3390/ani13010106 - 27 Dec 2022
Cited by 2 | Viewed by 6795
Abstract
Reptiles known as dinosaurs pervade scientific and popular culture, while interest in their genomics has increased since the 1990s. Birds (part of the crown group Reptilia) are living theropod dinosaurs. Chromosome-level genome assemblies cannot be made from long-extinct biological material, but dinosaur genome [...] Read more.
Reptiles known as dinosaurs pervade scientific and popular culture, while interest in their genomics has increased since the 1990s. Birds (part of the crown group Reptilia) are living theropod dinosaurs. Chromosome-level genome assemblies cannot be made from long-extinct biological material, but dinosaur genome organization can be inferred through comparative genomics of related extant species. Most reptiles apart from crocodilians have both macro- and microchromosomes; comparative genomics involving molecular cytogenetics and bioinformatics has established chromosomal relationships between many species. The capacity of dinosaurs to survive multiple extinction events is now well established, and birds now have more species in comparison with any other terrestrial vertebrate. This may be due, in part, to their karyotypic features, including a distinctive karyotype of around n = 40 (~10 macro and 30 microchromosomes). Similarity in genome organization in distantly related species suggests that the common avian ancestor had a similar karyotype to e.g., the chicken/emu/zebra finch. The close karyotypic similarity to the soft-shelled turtle (n = 33) suggests that this basic pattern was mostly established before the Testudine–Archosaur divergence, ~255 MYA. That is, dinosaurs most likely had similar karyotypes and their extensive phenotypic variation may have been mediated by increased random chromosome segregation and genetic recombination, which is inherently higher in karyotypes with more and smaller chromosomes. Full article
Show Figures

Figure 1

10 pages, 1389 KiB  
Review
A Brief Review of Meiotic Chromosomes in Early Spermatogenesis and Oogenesis and Mitotic Chromosomes in the Viviparous Lizard Zootoca vivipara (Squamata: Lacertidae) with Multiple Sex Chromosomes
by Larissa Kupriyanova and Larissa Safronova
Animals 2023, 13(1), 19; https://doi.org/10.3390/ani13010019 - 20 Dec 2022
Cited by 1 | Viewed by 1288
Abstract
This brief review is focused on the viviparous lizard Zootoca vivipara (Lichtenstein, 1823), of the family Lacertidae, which possesses female heterogamety and multiple sex chromosomes (male 2n = 36, Z1Z1Z2Z2/Z1Z2W, [...] Read more.
This brief review is focused on the viviparous lizard Zootoca vivipara (Lichtenstein, 1823), of the family Lacertidae, which possesses female heterogamety and multiple sex chromosomes (male 2n = 36, Z1Z1Z2Z2/Z1Z2W, female 2n = 35, with variable W sex chromosome). Multiple sex chromosomes and their changes may influence meiosis and the female meiotic drive, and they may play a role in reproductive isolation. In two cryptic taxa of Z. vivipara with different W sex chromosomes, meiosis during early spermatogenesis and oogenesis proceeds normally, without any disturbances, with the formation of haploid spermatocytes, and in female meiosis with the formation of synaptonemal complexes (SCs) and the lampbrush chromosomes. In females, the SC number was constantly equal to 19 (according to the SC length, 16 SC autosomal bivalents plus three presumed SC sex chromosome elements). No variability in the chromosomes at the early stages of meiotic prophase I, and no significant disturbances in the chromosome segregation at the anaphase–telophase I stage, have been discovered, and haploid oocytes (n = 17) at the metaphase II stage have been revealed. There should be a factor/factors that maintain the multiple sex chromosomes, their equal transmission, and the course of meiosis in these cryptic forms of Z. vivipara. Full article
Show Figures

Figure 1

Back to TopTop