scholarly journals MULTIPLE ORIGINS OF SEX CHROMOSOME FUSIONS CORRELATED WITH CHIASMA LOCALIZATION INHABRONATTUSJUMPING SPIDERS (ARANEAE: SALTICIDAE)

Evolution ◽  
2013 ◽  
Vol 67 (8) ◽  
pp. 2258-2272 ◽  
Author(s):  
Wayne P. Maddison ◽  
Geneviève Leduc-Robert
Keyword(s):  
Sex Chromosome ◽  
Multiple Origins ◽  
Chiasma Localization ◽  
Chromosome Fusions

scholarly journals Whole-chromosome fusions in the karyotype evolution of Sceloporus (Iguania, Reptilia) are more frequent in sex chromosomes than autosomes

2021 ◽  
Vol 376 (1833) ◽  
pp. 20200099
Author(s):  
Artem P. Lisachov ◽  
Katerina V. Tishakova ◽  
Svetlana A. Romanenko ◽  
Anna S. Molodtseva ◽  
Dmitry Yu. Prokopov ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Recombination Rate ◽  
Complex Analysis ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Synaptonemal Complex Analysis ◽  
Chromosome Fusions ◽  
Chromosome Formation ◽  
Pseudoautosomal Regions

Whole-chromosome fusions play a major role in the karyotypic evolution of reptiles. It has been suggested that certain chromosomes tend to fuse with sex chromosomes more frequently than others. However, the comparative genomic synteny data are too scarce to draw strong conclusions. We obtained and sequenced chromosome-specific DNA pools of Sceloporus malachiticus , an iguanian species which has experienced many chromosome fusions. We found that four of seven lineage-specific fusions involved sex chromosomes, and that certain syntenic blocks which constitute the sex chromosomes, such as the homologues of the Anolis carolinensis chromosomes 11 and 16, are repeatedly involved in sex chromosome formation in different squamate species. To test the hypothesis that the karyotypic shift could be associated with changes in recombination patterns, we performed a synaptonemal complex analysis in this species and in Sceloporus variabilis (2 n = 34). It revealed that the sex chromosomes in S. malachiticus had two distal pseudoautosomal regions and a medial differentiated region. We found that multiple fusions little affected the recombination rate in S. malachiticus . Our data confirm more frequent involvement of certain chromosomes in sex chromosome formation, but do not reveal a connection between the gonosome–autosome fusions and the evolution of recombination rate. This article is part of the theme issue ‘Challenging the paradigm in sex chromosome evolution: empirical and theoretical insights with a focus on vertebrates (Part II)’.

scholarly journals Chromosome fusions shape an ancient UV sex chromosome system

2020 ◽  
Author(s):  
Sarah B. Carey ◽  
Jerry Jenkins ◽  
Adam C. Payton ◽  
Shenqiang Shu ◽  
John T. Lovell ◽  
...  
Keyword(s):  
Gene Regulatory Networks ◽  
Sex Chromosomes ◽  
Regulatory Networks ◽  
Sex Chromosome ◽  
Structural Complexity ◽  
Sex Chromosome System ◽  
Chromosome Fusions ◽  
Gene Regulatory ◽  
Suppressed Recombination ◽  
Reference Genomes

AbstractSex chromosomes occur in diverse organisms, but their structural complexity has often prevented evolutionary analyses. Here we use two chromosome-scale reference genomes of the moss Ceratodon purpureus to trace the evolution of the sex chromosomes in bryophytes. Comparative analyses show the moss genome comprises seven remarkably stable ancestral chromosomal elements. An exception is the sex chromosomes, which share thousands of broadly-expressed genes but lack any synteny. We show the sex chromosomes evolved over 300 million years ago and expanded via at least two distinct chromosomal fusions. These results link suppressed recombination between the sex chromosomes with rapid structural change and the evolution of distinct transposable element compositions, and suggest haploid gene expression promotes the evolution of independent female and male gene-regulatory networks.One Sentence SummaryMoss sex chromosomes retain thousands of broadly-expressed genes despite millions of years of suppressed recombination.

scholarly journals Whole-genome analysis across 10 songbird families within Sylvioidea reveals a novel autosome–sex chromosome fusion

2020 ◽  
Vol 16 (4) ◽  
pp. 20200082 ◽  
Author(s):  
Hanna Sigeman ◽  
Suvi Ponnikas ◽  
Bengt Hansson
Keyword(s):  
Sex Chromosome ◽  
Whole Genome ◽  
Chromosome Fusion ◽  
Whole Genome Analysis ◽  
Genome Data ◽  
The Family ◽  
Single Clade ◽  
Sex Chromosome System ◽  
Chromosome Fusions ◽  
Taxonomic Groups

Sex chromosomes in birds have long been considered to be extremely stable. However, this notion has lately been challenged by findings of independent autosome–sex chromosome fusions within songbirds, several of which occur within a single clade, the superfamily Sylvioidea. To understand what ecological and evolutionary processes drive changes in sex chromosome systems, we need complete descriptions of sex chromosome diversity across taxonomic groups. Here, we characterize the sex chromosome systems across Sylvioidea using whole-genome data of species representatives of 10 different families, including two published and eight new genomes. We describe a novel fusion in the family Cisticolidae (represented by Cisticola juncidis ) involving a part of chromosome 4. We also confirm the previously identified fusion between chromosome Z and a part of chromosome 4A in all 10 families and show that fusions involving parts of chromosomes 3 and 5 are not found outside the families where they were first discovered (Alaudidae and Panuridae). These findings add to the complexity of the sex chromosome system in Sylvioidea, where four independent autosome–sex chromosome fusions have now been identified.

scholarly journals Repeated sex chromosome evolution in vertebrates supported by expanded avian sex chromosomes

2019 ◽  
Vol 286 (1916) ◽  
pp. 20192051 ◽  
Author(s):  
Hanna Sigeman ◽  
Suvi Ponnikas ◽  
Pallavi Chauhan ◽  
Elisa Dierickx ◽  
M. de L. Brooke ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Chromosome 3 ◽  
Sex Chromosome Evolution ◽  
Recombination Suppression ◽  
Time Points ◽  
Repeated Evolution ◽  
Chromosome Fusions ◽  
Selection For

Sex chromosomes have evolved from the same autosomes multiple times across vertebrates, suggesting that selection for recombination suppression has acted repeatedly and independently on certain genetic backgrounds. Here, we perform comparative genomics of a bird clade (larks and their sister lineage; Alaudidae and Panuridae) where multiple autosome–sex chromosome fusions appear to have formed expanded sex chromosomes. 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. Within these four chromosomes, we found evidence of five evolutionary strata where recombination had been suppressed at different time points, and show that stratum age explained the divergence rate of Z–W gametologs. Next, we analysed chromosome content and found that chromosome 3 was significantly enriched for genes with predicted sex-related functions. Finally, we demonstrate extensive homology to sex chromosomes in other vertebrate lineages: chromosomes Z, 3, 4A and 5 have independently evolved into sex chromosomes in fish (Z), turtles (Z, 5), lizards (Z, 4A), mammals (Z, 4A) and frogs (Z, 3, 4A, 5). Our results provide insights into and support for repeated evolution of sex chromosomes in vertebrates.

scholarly journals Whole-chromosome fusions in the karyotype evolution of Sceloporus (Iguania, Reptilia) are more intense in sex chromosomes than autosomes

2020 ◽  
Author(s):  
Artem P. Lisachov ◽  
Katerina V. Tishakova ◽  
Svetlana A. Romanenko ◽  
Anna S. Molodtseva ◽  
Dmitry Yu. Prokopov ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Complex Analysis ◽  
Sex Chromosome ◽  
Chromosome 11 ◽  
Evolutionary Forces ◽  
Chromosome Synapsis ◽  
Synaptonemal Complex Analysis ◽  
Chromosome Fusions ◽  
Chromosome Formation ◽  
Pseudoautosomal Regions

AbstractThere is a growing body of evidence that the common ancestor of vertebrates had a bimodal karyotype, i.e. consisting of large macrochromosomes and small microchromosomes. This type of karyotype organization is preserved in most reptiles. However, certain species independently experience microchromosome fusions. The evolutionary forces behind this are unclear. We investigated the karyotype of the green spiny lizard, Sceloporus malachiticus, an iguana species which has 2n=22, whereas the ancestral karyotype of iguanas had 2n=36. We obtained and sequenced flow-sorted chromosome-specific DNA samples and found that most of the microchromosome fusions in this species involved sex chromosomes. We found that certain ancestral squamate chromosomes, such as the homologue of the Anolis carolinensis chromosome 11, are repeatedly involved in sex chromosome formation in different species. To test the hypothesis that the karyotypic shift could be associated with changes in recombination patterns, and to study sex chromosome synapsis and recombination in meiosis, we performed synaptonemal complex analysis in this species and in S. variabilis, a related species with 2n=34. We found that in the species studied the recombination patterns correlate more with phylogeny than with the structure of the karyotype. The sex chromosomes had two distal pseudoautosomal regions and a medial differentiated region.

scholarly journals Y Fuse? Sex Chromosome Fusions in Fishes and Reptiles

PLoS Genetics ◽  
2015 ◽  
Vol 11 (5) ◽  
pp. e1005237 ◽  
Author(s):  
Matthew W. Pennell ◽  
Mark Kirkpatrick ◽  
Sarah P. Otto ◽  
Jana C. Vamosi ◽  
Catherine L. Peichel ◽  
...  
Keyword(s):  
Sex Chromosome ◽  
Chromosome Fusions

Comparative Analysis of Genetic and Morphological Variation within the Platanthera hyperborea Complex (Orchidaceae)

2020 ◽  
Vol 45 (4) ◽  
pp. 767-778
Author(s):  
Eranga Wettewa ◽  
Nick Bailey ◽  
Lisa E. Wallace
Keyword(s):  
North America ◽  
Diploid Species ◽  
Morphological Characters ◽  
Evolutionary Patterns ◽  
Founding Population ◽  
Multiple Origins ◽  
Geographic Structure ◽  
Species Complexes ◽  
Nuclear Its ◽  
Cryptic Taxa

Abstract—Species complexes present considerable problems for a working taxonomy due to the presence of intraspecific variation, hybridization, polyploidy, and phenotypic plasticity. Understanding evolutionary patterns using molecular markers can allow for a more thorough assessment of evolutionary lineages than traditional morphological markers. In this study, we evaluated genetic diversity and phylogenetic patterns among taxa of the Platanthera hyperborea (Orchidaceae) complex, which includes diploid (Platanthera aquilonis) and polyploid (Platanthera hyperborea, P. huronensis, and P. convallariifolia) taxa spanning North America, Greenland, Iceland, and Asia. We found that three floral morphological characters overlap among the polyploid taxa, but the diploid species has smaller flowers. DNA sequence variation in a plastid (rpL16 intron) and a nuclear (ITS) marker indicated that at least three diploid species have contributed to the genomes of the polyploid taxa, suggesting all are of allopolyploid origin. Platanthera convallariifolia is most like P. dilatata and P. stricta, whereas P. huronensis and P. hyperborea appear to have originated from crosses of P. dilatata and P. aquilonis. Platanthera huronensis, which is found across North America, has multiple origins and reciprocal maternal parentage from the diploid species. By contrast, P. hyperborea, restricted to Greenland and Iceland, appears to have originated from a small founding population of hybrids in which P. dilatata was the maternal parent. Geographic structure was found among polyploid forms in North America. The area of Manitoba, Canada appears to be a contact zone among geographically diverse forms from eastern and western North America. Given the geographic and genetic variation found, we recommend continued recognition of four green-flowered species within this complex, but caution that there may be additional cryptic taxa within North America.

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