Chromosome evolution within theOrnithogalum tenuifolium complex (Hyacinthaceae), with special emphasis on the evolution of bimodal karyotypes

Stingless bees of the genus Melipona are subdivided into 4 subgenera called Eomelipona, Melikerria, Melipona sensu stricto, and Michmelia according to species morphology. Cytogenetically, the species of the genus Melipona show variation in the amount and distribution of heterochromatin along their chromosomes and can be separated into 2 groups: the first with low content of heterochromatin and the second with high content of heterochromatin. These heterochromatin patterns and the number of chromosomes are characteristics exclusive to Melipona karyotypes that distinguish them from the other genera of the Meliponini. To better understand the karyotype organization in Melipona and the relationship among the subgenera, we mapped repetitive sequences and analyzed previously reported cytogenetic data with the aim to identify cytogenetic markers to be used for investigating the phylogenetic relationships and chromosome evolution in the genus. In general, Melipona species have 2n = 18 chromosomes, and the species of each subgenus share the same characteristics in relation to heterochromatin regions, DAPI/CMA3 fluorophores, and the number and distribution of 18S rDNA sites. Microsatellites were observed only in euchromatin regions, whereas the (TTAGG)6 repeats were found at telomeric sites in both groups. Our data indicate that in addition to the chromosome number, the karyotypes in Melipona could be separated into 2 groups that are characterized by conserved cytogenetic features and patterns that generally are shared by species within each subgenus, which may reflect evolutionary constraints. Our results agree with the morphological separation of the Melipona into 4 subgenera, suggesting that they must be independent evolutionary lineages.

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Microsatellite and Chromosome Evolution of Parthenogenetic Sitobion Aphids in Australia

Genetics ◽

10.1093/genetics/144.2.747 ◽

1996 ◽

Vol 144 (2) ◽

pp. 747-756 ◽

Cited By ~ 4

Author(s):

Paul Sunnucks ◽

Phillip R England ◽

Andrea C Taylor ◽

Dinah F Hales

Keyword(s):

Sexual Reproduction ◽

Chromosome Evolution ◽

Genetic Recombination ◽

Allelic Variation ◽

Repeat Unit ◽

Chromosomal Evolution ◽

Microsatellite Variation ◽

Wide Range ◽

Sexual Recombination ◽

Minimum Numbers

Abstract Single-locus microsatellite variation correlated perfectly with chromosome number in Sitobion miscanthi aphids. The microsatellites were highly heterozygous, with up to 10 alleles per locus in this species. Despite this considerable allelic variation, only seven different S. miscanthi genotypes were discovered in 555 individuals collected from a wide range of locations, hosts and sampling periods. Relatedness between genotypes suggests only two successful colonizations of Australia. There was no evidence for genetic recombination in 555 S. miscanthi so the occurrence of recent sexual reproduction must be near zero. Thus diversification is by mutation and chromosomal rearrangement alone. Since the aphids showed no sexual recombination, microsatellites can mutate without meiosis. Five of seven microsatellite differences were a single repeat unit, and one larger jump is likely. The minimum numbers of changes between karyotypes corresponded roughly one-to-one with microsatellite allele changes, which suggests very rapid chromosomal evolution. A chromosomal fission occurred in a cultured line, and a previously unknown chromosomal race was detected. All 121 diverse S. near fragariae were heterozygous but revealed only one genotype. This species too must have a low rate of sexual reproduction and few colonizations of Australia.

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The Diversity and Evolution of Sex Chromosomes in Frogs

Genes ◽

10.3390/genes12040483 ◽

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.

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Limitation of current probe design for oligo-cross-FISH, exemplified by chromosome evolution studies in duckweeds

Chromosoma ◽

10.1007/s00412-020-00749-2 ◽

2021 ◽

Vol 130 (1) ◽

pp. 15-25

Author(s):

Phuong T. N. Hoang ◽

Jean-Marie Rouillard ◽

Jiří Macas ◽

Ivona Kubalová ◽

Veit Schubert ◽

...

Keyword(s):

Growth Rate ◽

Chromosome Number ◽

Chromosome Evolution ◽

Sequence Similarity ◽

Flowering Plants ◽

The Other ◽

Probe Design ◽

Congeneric Species ◽

Specific Design ◽

Spirodela Polyrhiza

AbstractDuckweeds represent a small, free-floating aquatic family (Lemnaceae) of the monocot order Alismatales with the fastest growth rate among flowering plants. They comprise five genera (Spirodela, Landoltia, Lemna, Wolffiella, and Wolffia) varying in genome size and chromosome number. Spirodela polyrhiza had the first sequenced duckweed genome. Cytogenetic maps are available for both species of the genus Spirodela (S. polyrhiza and S. intermedia). However, elucidation of chromosome homeology and evolutionary chromosome rearrangements by cross-FISH using Spirodela BAC probes to species of other duckweed genera has not been successful so far. We investigated the potential of chromosome-specific oligo-FISH probes to address these topics. We designed oligo-FISH probes specific for one S. intermedia and one S. polyrhiza chromosome (Fig. 1a). Our results show that these oligo-probes cross-hybridize with the homeologous regions of the other congeneric species, but are not suitable to uncover chromosomal homeology across duckweeds genera. This is most likely due to too low sequence similarity between the investigated genera and/or too low probe density on the target genomes. Finally, we suggest genus-specific design of oligo-probes to elucidate chromosome evolution across duckweed genera.

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Chromosomal Analysis in Crotophaga ani (Aves, Cuculiformes) Reveals Extensive Genomic Reorganization and an Unusual Z-Autosome Robertsonian Translocation

Cells ◽

10.3390/cells10010004 ◽

2020 ◽

Vol 10 (1) ◽

pp. 4

Author(s):

Rafael Kretschmer ◽

Ricardo José Gunski ◽

Analía del Valle Garnero ◽

Thales Renato Ochotorena de Freitas ◽

Gustavo Akira Toma ◽

...

Keyword(s):

Robertsonian Translocation ◽

Chromosome Evolution ◽

Sex Chromosome ◽

Rare Event ◽

Chromosome Morphology ◽

Z Chromosome ◽

Molecular Cytogenetic ◽

Intrachromosomal Rearrangements ◽

Genomic Reorganization

Although cytogenetics studies in cuckoos (Aves, Cuculiformes) have demonstrated an interesting karyotype variation, such as variations in the chromosome morphology and diploid number, their chromosome organization and evolution, and relation with other birds are poorly understood. Hence, we combined conventional and molecular cytogenetic approaches to investigate chromosome homologies between chicken and the smooth-billed ani (Crotophaga ani). Our results demonstrate extensive chromosome reorganization in C. ani, with interchromosomal rearrangements involving macro and microchromosomes. Intrachromosomal rearrangements were observed in some macrochromosomes, including the Z chromosome. The most evolutionary notable finding was a Robertsonian translocation between the microchromosome 17 and the Z chromosome, a rare event in birds. Additionally, the simple short repeats (SSRs) tested here were preferentially accumulated in the microchromosomes and in the Z and W chromosomes, showing no relationship with the constitutive heterochromatin regions, except in the W chromosome. Taken together, our results suggest that the avian sex chromosome is more complex than previously postulated and revealed the role of microchromosomes in the avian sex chromosome evolution, especially cuckoos.

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Correction to: Evolutionary pattern of karyotypes and meiosis in pholcid spiders (Araneae: Pholcidae): implications for reconstructing chromosome evolution of araneomorph spiders

BMC Ecology and Evolution ◽

10.1186/s12862-021-01828-3 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Ivalú M. Ávila Herrera ◽

Jiří Král ◽

Markéta Pastuchová ◽

Martin Forman ◽

Jana Musilová ◽

...

Keyword(s):

Chromosome Evolution ◽

Evolutionary Pattern

An amendment to this paper has been published and can be accessed via the original article.

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