scholarly journals The Evolution of Sex Chromosomes and Sex Determination in Vertebrates and the Key Role of DMRT1

2006 ◽  
Vol 1 (1) ◽  
pp. 2-11 ◽  
Author(s):  
M. Ferguson-Smith
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Evolution Of Sex

scholarly journals Sex chromosome evolution: historical insights and future perspectives

2017 ◽  
Vol 284 (1854) ◽  
pp. 20162806 ◽  
Author(s):  
Jessica K. Abbott ◽  
Anna K. Nordén ◽  
Bengt Hansson
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Empirical Studies ◽  
Analytical Models ◽  
Specific Gene ◽  
Sex Chromosome Evolution ◽  
Current Thinking

Many separate-sexed organisms have sex chromosomes controlling sex determination. Sex chromosomes often have reduced recombination, specialized (frequently sex-specific) gene content, dosage compensation and heteromorphic size. Research on sex determination and sex chromosome evolution has increased over the past decade and is today a very active field. However, some areas within the field have not received as much attention as others. We therefore believe that a historic overview of key findings and empirical discoveries will put current thinking into context and help us better understand where to go next. Here, we present a timeline of important conceptual and analytical models, as well as empirical studies that have advanced the field and changed our understanding of the evolution of sex chromosomes. Finally, we highlight gaps in our knowledge so far and propose some specific areas within the field that we recommend a greater focus on in the future, including the role of ecology in sex chromosome evolution and new multilocus models of sex chromosome divergence.

scholarly journals Independent Evolution of Sex Chromosomes in Eublepharid Geckos, a Lineage with Environmental and Genotypic Sex Determination

2020 ◽  
Author(s):  
Eleonora Pensabene ◽  
Lukáš Kratochvíl ◽  
Michail Rovatsos
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Gene Content ◽  
Gene Copy ◽  
Specific Gene ◽  
Evolution Of Sex ◽  
Copy Numbers ◽  
Genotypic Sex Determination ◽  
The Difference ◽  
Genomic Regions

Geckos demonstrate a remarkable variability in sex determination systems, but our limited knowledge prohibits accurate conclusions on the evolution of sex determination in this group. Eyelid geckos (Eublepharidae) are of particular interest, as they encompass species with both environmental and genotypic sex determination. We identified for the first time the X-specific gene content in the Yucatán banded gecko, Coleonyx elegans, possessing X1X1X2X2/X1X2Y multiple sex chromosomes by comparative genome coverage analysis between sexes. The X-specific gene content of Coleonyx elegans was revealed to be partially homologous to genomic regions linked to the chicken autosomes 1, 6 and 11. A qPCR-based test was applied to validate a subset of X-specific genes by comparing the difference in gene copy numbers between sexes, and to explore the homology of sex chromosomes across 11 eublepharid, two phyllodactylid and one sphaerodactylid species. Homologous sex chromosomes are shared between Coleonyx elegans and Coleonyx mitratus, two species diverged approximately 34 million years ago, but not with other tested species. As far as we know, the X-specific gene content of Coleonyx elegans / Coleonyx mitratus was never involved in the sex chromosomes of other gecko lineages, indicating that the sex chromosomes in this clade of eublepharid geckos evolved independently.

scholarly journals The diversity of plant sex chromosomes highlighted through advances in genome sequencing

2021 ◽  
Author(s):  
Sarah Carey ◽  
Qingyi Yu ◽  
Alex Harkess
Keyword(s):  
Sex Determination ◽  
Genome Sequencing ◽  
Sex Chromosomes ◽  
Theoretical Models ◽  
Genomic Technologies ◽  
Interdisciplinary Approaches ◽  
Suppressed Recombination ◽  
Plant Sex Chromosomes ◽  
Plant Sex

For centuries scientists have been intrigued by the origin of dioecy in plants, characterizing sex-specific development, uncovering cytological differences between the sexes, and developing theoretical models. However, through the invention and continued improvements in genomic technologies, we have truly begun to unlock the genetic basis of dioecy in many species. Here we broadly review the advances in research on dioecy and sex chromosomes. We start by first discussing the early works that built the foundation for current studies and the advances in genome sequencing that have facilitated more-recent findings. We next discuss the analyses of sex chromosomes and sex-determination genes uncovered by genome sequencing. We synthesize these results to find some patterns are emerging, such as the role of duplications, the involvement of hormones in sex-determination, and support for the two-locus model for the origin of dioecy. Though across systems, there also many novel insights into how sex chromosomes evolve, including different sex-determining genes and routes to suppressed recombination. We propose the future of research in plant sex chromosomes should involve interdisciplinary approaches, combining cutting-edge technologies with the classics to unravel the patterns that can be found across the hundreds of independent origins.

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

Life ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 342
Author(s):  
Eleonora Pensabene ◽  
Lukáš Kratochvíl ◽  
Michail Rovatsos
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Gene Content ◽  
Gene Copy ◽  
Specific Gene ◽  
Evolution Of Sex ◽  
Copy Numbers ◽  
Genotypic Sex Determination ◽  
The Difference ◽  
Genomic Regions

Geckos demonstrate a remarkable variability in sex determination systems, but our limited knowledge prohibits accurate conclusions on the evolution of sex determination in this group. Eyelid geckos (Eublepharidae) are of particular interest, as they encompass species with both environmental and genotypic sex determination. We identified for the first time the X-specific gene content in the Yucatán banded gecko, Coleonyx elegans, possessing X1X1X2X2/X1X2Y multiple sex chromosomes by comparative genome coverage analysis between sexes. The X-specific gene content of Coleonyx elegans was revealed to be partially homologous to genomic regions linked to the chicken autosomes 1, 6 and 11. A qPCR-based test was applied to validate a subset of X-specific genes by comparing the difference in gene copy numbers between sexes, and to explore the homology of sex chromosomes across eleven eublepharid, two phyllodactylid and one sphaerodactylid species. Homologous sex chromosomes are shared between Coleonyx elegans and Coleonyx mitratus, two species diverged approximately 34 million years ago, but not with other tested species. As far as we know, the X-specific gene content of Coleonyx elegans / Coleonyx mitratus was never involved in the sex chromosomes of other gecko lineages, indicating that the sex chromosomes in this clade of eublepharid geckos evolved independently.

scholarly journals Genomics of expanded avian sex chromosomes shows that certain chromosomes are predisposed towards sex-linkage in vertebrates

2019 ◽  
Author(s):  
Hanna Sigeman ◽  
Suvi Ponnikas ◽  
Pallavi Chauhan ◽  
Elisa Dierickx ◽  
M. de L. Brooke ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Sex Chromosomes ◽  
Sex Chromosome ◽  
Chromosome 3 ◽  
Sex Linkage ◽  
Evolution Of Sex ◽  
Fourth Chromosome ◽  
Time Points ◽  
Genomic Regions

ABSTRACTSex chromosomes have evolved from the same autosomes multiple times across vertebrates, suggesting that certain genomic regions are predisposed towards sex-linkage. However, to test this hypothesis detailed studies of independently originated sex-linked regions and their gene content are needed. Here we address this problem through comparative genomics of birds where multiple chromosomes appear to have formed neo-sex chromosomes: larks (Alaudidae; Sylvioidea). We detected the largest known avian sex chromosome (195.3 Mbp) and show that it originates from fusions between (parts of) four avian chromosomes (Z, 3, 4A and 5). We found evidence of five evolutionary strata where recombination has been suppressed at different time points, and that these time points correlate with the level of Z–W gametolog differentiation. We show that there is extensive homology to sex chromosomes in other vertebrate lineages: three of the fused chromosomes (Z, 4A, 5) have independently evolved into sex chromosomes in fish (Z), turtles (Z, 5), lizards (Z, 4A) and mammals (Z, 4A). Moreover, we found that the fourth chromosome, chromosome 3, was significantly enriched for genes with predicted sex-specific functions. These results support a key role of chromosome content in the evolution of sex chromosomes in vertebrates.

Sensing Non-sense in Animal Sex From Perspective of Transposable Elements

2021 ◽  
Vol 1 (2) ◽  
pp. 1-9
Author(s):  
Ayan Mukherjee
Keyword(s):  
Transposable Elements ◽  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosomal Rearrangement ◽  
Repetitive Sequences ◽  
Regulatory Elements ◽  
Vertebrate Species ◽  
Temperature Dependent ◽  
Genomic Regions

Evolution of vertebrate species took shape through millions of years, where sex played an important role in maintenance of a lineage, genetic diversifications and reproductive isolation. On due course of sexual evolution, sex determination strategies have been proposed to flow from temperature dependent sex determination to genetic sex determination, which has been demonstrated as XY system in mammals and ZW system in birds. In contrary to this established conception, different lineages showed to have overlapping sex determining strategies. While searching possible reasons for these phenomenons, researchers observed that gene content of sex chromosomes is highly variable as far as their location and prevalence is concerned, which otherwise suggested autosomal origin of sex chromosomes. Although the exact mechanisms of gene transfer and thereby origin of sex chromosomes are yet to be unveiled, but chromosomal rearrangement and introgression has been hypothesized to be the possible effector. Transposable elements (TEs) are long been considered to be ‘Selfish’ or ‘Junk’ DNA material as most of the non-coding genomic regions are comprised by TEs, which did not make any sense to be a part of species genome. But recently, TEs are being considered to be a nature’s tool for biological innovation by creating new regulatory elements, new coding sequences, genetic disruption and chromosomal remodelling. So, this has been postulated that TEs could facilitate rearrangement and introgression, which ultimately lead to evolution of sex chromosomes and sex determining genes through positive selection. Prevalence of highly repetitive sequences in sex chromosomes, particularly in Y, makes it a hot bed for TEs mediated rearrangement and introgression. In this review, I tried to discuss whether it makes any sense to focus on the role of TEs in sexual evolution of animals.

scholarly journals Evolution of sex determination mechanisms and sex chromosomes

2019 ◽  
Vol 49 (4) ◽  
pp. 403-420
Author(s):  
RuiFeng WU ◽  
XiaoMan XU ◽  
Qi ZHOU
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Evolution Of Sex ◽  
Sex Determination Mechanisms

scholarly journals The Diversity of Plant Sex Chromosomes Highlighted through Advances in Genome Sequencing

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
Sarah Carey ◽  
Qingyi Yu ◽  
Alex Harkess
Keyword(s):  
Sex Determination ◽  
Genome Sequencing ◽  
Sex Chromosomes ◽  
Theoretical Models ◽  
Genomic Technologies ◽  
Interdisciplinary Approaches ◽  
Suppressed Recombination ◽  
Plant Sex Chromosomes ◽  
Plant Sex

For centuries, scientists have been intrigued by the origin of dioecy in plants, characterizing sex-specific development, uncovering cytological differences between the sexes, and developing theoretical models. Through the invention and continued improvements in genomic technologies, we have truly begun to unlock the genetic basis of dioecy in many species. Here we broadly review the advances in research on dioecy and sex chromosomes. We start by first discussing the early works that built the foundation for current studies and the advances in genome sequencing that have facilitated more-recent findings. We next discuss the analyses of sex chromosomes and sex-determination genes uncovered by genome sequencing. We synthesize these results to find some patterns are emerging, such as the role of duplications, the involvement of hormones in sex-determination, and support for the two-locus model for the origin of dioecy. Though across systems, there are also many novel insights into how sex chromosomes evolve, including different sex-determining genes and routes to suppressed recombination. We propose the future of research in plant sex chromosomes should involve interdisciplinary approaches, combining cutting-edge technologies with the classics to unravel the patterns that can be found across the hundreds of independent origins.

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