scholarly journals Does the speciation clock tick more slowly in the absence of heteromorphic sex chromosomes?

BioEssays ◽  
2012 ◽  
Vol 34 (3) ◽  
pp. 166-169 ◽  
Author(s):  
Barret C. Phillips ◽  
Suzanne Edmands
Keyword(s):  
Sex Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Clock Tick

scholarly journals The Diversity and Evolution of Sex Chromosomes in Frogs

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 483
Author(s):  
Wen-Juan Ma ◽  
Paris Veltsos
Keyword(s):  
Sex Determination ◽  
Sex Chromosomes ◽  
Chromosome Evolution ◽  
Sex Chromosome ◽  
Comparative Genomic ◽  
Ancestral State ◽  
Heteromorphic Sex Chromosomes ◽  
Genomic Studies ◽  
Evolutionary Trajectories ◽  
Heterogametic Sex

Frogs are ideal organisms for studying sex chromosome evolution because of their diversity in sex chromosome differentiation and sex-determination systems. We review 222 anuran frogs, spanning ~220 Myr of divergence, with characterized sex chromosomes, and discuss their evolution, phylogenetic distribution and transitions between homomorphic and heteromorphic states, as well as between sex-determination systems. Most (~75%) anurans have homomorphic sex chromosomes, with XY systems being three times more common than ZW systems. Most remaining anurans (~25%) have heteromorphic sex chromosomes, with XY and ZW systems almost equally represented. There are Y-autosome fusions in 11 species, and no W-/Z-/X-autosome fusions are known. The phylogeny represents at least 19 transitions between sex-determination systems and at least 16 cases of independent evolution of heteromorphic sex chromosomes from homomorphy, the likely ancestral state. Five lineages mostly have heteromorphic sex chromosomes, which might have evolved due to demographic and sexual selection attributes of those lineages. Males do not recombine over most of their genome, regardless of which is the heterogametic sex. Nevertheless, telomere-restricted recombination between ZW chromosomes has evolved at least once. More comparative genomic studies are needed to understand the evolutionary trajectories of sex chromosomes among frog lineages, especially in the ZW systems.

scholarly journals Localization of Male-Specifically Expressed MROS Genes of Silene latifolia by PCR on Flow-Sorted Sex Chromosomes and Autosomes

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1269-1277
Author(s):  
Eduard Kejnovský ◽  
Jan Vrána ◽  
Sachihiro Matsunaga ◽  
Přemysl Souček ◽  
Jiří Široký ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Homology Search ◽  
X Chromosomes ◽  
Dioecious Plants ◽  
Flow Sorting ◽  
Heteromorphic Sex Chromosomes ◽  
Copy Gene ◽  
Melandrium Album ◽  
Pcr Products

Abstract The dioecious white campion Silene latifolia (syn. Melandrium album) has heteromorphic sex chromosomes, XX in females and XY in males, that are larger than the autosomes and enable their separation by flow sorting. The group of MROS genes, the first male-specifically expressed genes in dioecious plants, was recently identified in S. latifolia. To localize the MROS genes, we used the flow-sorted X chromosomes and autosomes as a template for PCR with internal primers. Our results indicate that the MROS3 gene is located in at least two copies tandemly arranged on the X chromosome with additional copy(ies) on the autosome(s), while MROS1, MROS2, and MROS4 are exclusively autosomal. The specificity of PCR products was checked by digestion with a restriction enzyme or reamplification using nested primers. Homology search of databases has shown the presence of five MROS3 homologues in A. thaliana, four of them arranged in two tandems, each consisting of two copies. We conclude that MROS3 is a low-copy gene family, connected with the proper pollen development, which is present not only in dioecious but also in other dicot plant species.

Genetic and cytogenetic analysis of the fruit fly Rhagoletis cerasi (Diptera: Tephritidae)

Genome ◽  
2008 ◽  
Vol 51 (7) ◽  
pp. 479-491 ◽  
Author(s):  
Ilias Kounatidis ◽  
Nikolaos Papadopoulos ◽  
Kostas Bourtzis ◽  
Penelope Mavragani-Tsipidou
Keyword(s):  
Salivary Gland ◽  
Sex Chromosomes ◽  
Cytogenetic Analysis ◽  
Polytene Chromosomes ◽  
Fruit Fly ◽  
Pest Species ◽  
Heteromorphic Sex Chromosomes ◽  
Weak Points ◽  
Heterogametic Sex ◽  
Rhagoletis Cerasi

The European cherry fruit fly, Rhagoletis cerasi , is a major agricultural pest for which biological, genetic, and cytogenetic information is limited. We report here a cytogenetic analysis of 4 natural Greek populations of R. cerasi, all of them infected with the endosymbiotic bacterium Wolbachia pipientis . The mitotic karyotype and detailed photographic maps of the salivary gland polytene chromosomes of this pest species are presented here. The mitotic metaphase complement consists of 6 pairs of chromosomes, including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the salivary gland polytene complement has shown a total of 5 long chromosomes (10 polytene arms) that correspond to the 5 autosomes of the mitotic nuclei and a heterochromatic mass corresponding to the sex chromosomes. The most prominent landmarks of each polytene chromosome, the “weak points”, and the unusual asynapsis of homologous pairs of polytene chromosomes at certain regions of the polytene elements are also presented and discussed.

scholarly journals Sex-dependent dominance maintains migration supergene in rainbow trout

2018 ◽  
Author(s):  
Devon E. Pearse ◽  
Nicola J. Barson ◽  
Torfinn Nome ◽  
Guangtu Gao ◽  
Matthew A. Campbell ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Sex Chromosomes ◽  
Sexual Conflict ◽  
Genetic Basis ◽  
Deleterious Mutation ◽  
Deleterious Mutations ◽  
Heteromorphic Sex Chromosomes ◽  
Males And Females ◽  
Shared Genetic ◽  
Environmental Dependence

AbstractTraits with different fitness optima in males and females cause sexual conflict when they have a shared genetic basis. Heteromorphic sex chromosomes can resolve this conflict and protect sexually antagonistic polymorphisms but accumulate deleterious mutations. However, many taxa lack differentiated sex chromosomes, and how sexual conflict is resolved in these species is largely unknown. Here we present a chromosome-anchored genome assembly for rainbow trout (Oncorhynchus mykiss) and characterize a 56 Mb double-inversion supergene that mediates sex-specific migration through sex-dependent dominance, a mechanism that reduces sexual conflict. The double-inversion contains key photosensory, circadian rhythm, adiposity, and sexual differentiation genes and displays frequency clines associated with latitude and temperature, revealing environmental dependence. Our results constitute the first example of sex-dependent dominance across a large autosomal supergene, a novel mechanism for sexual conflict resolution capable of protecting polygenic sexually antagonistic variation while avoiding the homozygous lethality and deleterious mutation load of heteromorphic sex chromosomes.

Heteromorphic Sex Chromosomes and Their DNA Content in Fish: An Insight through Satellite DNA Accumulation in Megaleporinus elongatus

2020 ◽  
Vol 160 (1) ◽  
pp. 38-46 ◽  
Author(s):  
Carolina Crepaldi ◽  
Patricia P. Parise-Maltempi
Keyword(s):  
Sex Chromosomes ◽  
Dna Content ◽  
Satellite Dna ◽  
Sex Chromosome ◽  
Neotropical Fish ◽  
High Throughput Analysis ◽  
Multiple Sex Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Sex Chromosome System ◽  
Graph Based Clustering

The repetitive DNA content of fish sex chromosomes provides valuable insights into specificities and patterns of their genetic sex determination systems. In this study, we revealed the genomic satellite DNA (satDNA) content of Megaleporinuselongatus, a Neotropical fish species with Z1Z1Z2Z2/Z1W1Z2W2 multiple sex chromosomes, through high-throughput analysis and graph-based clustering, isolating 68 satDNA families. By physically mapping these sequences in female metaphases, we discovered 15 of the most abundant satDNAs clustered in its chromosomes, 9 of which were found exclusively in the highly heterochromatic W1. This heteromorphic sex chromosome showed the highest amount of satDNA accumulations in this species. The second most abundant family, MelSat02-26, shared FISH signals with the NOR-bearing pair in similar patterns and is linked to the multiple sex chromosome system. Our results demonstrate the diverse satDNA content in M. elongatus, especially in its heteromorphic sex chromosome. Additionally, we highlighted the different accumulation patterns and distribution of these sequences across species by physically mapping these satDNAs in other Anostomidae, Megaleporinusmacrocephalus and Leporinusfriderici (a species without differentiated sex chromosomes).

THE EVOLUTION OF HETEROMORPHIC SEX CHROMOSOMES

1990 ◽  
Vol 65 (3) ◽  
pp. 249-276 ◽  
Author(s):  
EVA JABLONKA ◽  
MARION J. LAMB
Keyword(s):  
Sex Chromosomes ◽  
Heteromorphic Sex Chromosomes

DIFFERENTIAL DNA REPLICATION IN THE XX AND XY CELLS OF MUSCA DOMESTICA L. OCRA STRAIN

1970 ◽  
Vol 12 (3) ◽  
pp. 461-473 ◽  
Author(s):  
K. Y. Jan ◽  
J. W. Boyes
Keyword(s):  
Dna Replication ◽  
Musca Domestica ◽  
Sex Chromosomes ◽  
Chromosome Length ◽  
Final Part ◽  
X Chromosomes ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Autosomal Pair ◽  
Differential Dna Replication

The karyotype of Musca domestica L. ocra strain, consists of the sex chromosomes and five autosomal pairs. The heteromorphic sex chromosomes are heterochromatic and mitotically unpaired, whereas the autosomes are euchromatic and mitotically paired. All autosomal pairs and both X and Y chromosomes are cytologically recognizable.The relative labelling rate, R (in terms of the number of grains counted per 100 labelled metaphases per μ of chromosome length) for the sex chromosomes and for each autosomal pair was followed from 1.5 hours to 8 hours after H3TdR injection. The pattern of labelling rate was similar for the different autosomal pairs in the XX cells but this pattern for the autosomal pairs in the XY cells, though also similar for the different pairs, differed appreciably from that found in the XX cells. The pattern of the labelling rate for the X chromosomes was similar in the XX and XY cells. Also the pattern of labelling rate for the X and Y chromosomes was similar during the final part of the replication period. The two X chromosomes in the XX cells and the X and Y chromosomes in the XY cells completed labelling later than the autosomes.

scholarly journals Gene Duplication and the Genome Distribution of Sex-Biased Genes

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Miguel Gallach ◽  
Susana Domingues ◽  
Esther Betrán
Keyword(s):  
Sexual Dimorphism ◽  
Gene Duplication ◽  
Sex Chromosomes ◽  
Genetic Basis ◽  
Distribution Patterns ◽  
Current Data ◽  
Evolutionary Patterns ◽  
Single Genome ◽  
Heteromorphic Sex Chromosomes ◽  
Genetic Conflicts

In species that have two sexes, a single genome encodes two morphs, as each sex can be thought of as a distinct morph. This means that the same set of genes are differentially expressed in the different sexes. Many questions emanate from this statement. What proportion of genes contributes to sexual dimorphism? How do they contribute to sexual dimorphism? How is sex-biased expression achieved? Which sex and what tissues contribute the most to sex-biased expression? Do sex-biased genes have the same evolutionary patterns as nonbiased genes? We review the current data on sex-biased expression in species with heteromorphic sex chromosomes and comment on the most important hypotheses suggested to explain the origin, evolution, and distribution patterns of sex-biased genes. In this perspective we emphasize how gene duplication serves as an important molecular mechanism to resolve genomic clashes and genetic conflicts by generating sex-biased genes, often sex-specific genes, and contributes greatly to the underlying genetic basis of sexual dimorphism.

Sign in / Sign up

Export Citation Format

Share Document