Evidence for chromosome number reduction and chromosomal homosequentiality in the 24-chromosome Korean frog Rana dybowskii and related species

Chromosoma ◽  
1983 ◽  
Vol 88 (3) ◽  
pp. 222-226 ◽  
Author(s):  
David M. Green
Keyword(s):  
Chromosome Number ◽  
Related Species ◽  
Rana Dybowskii

A new species of Gomesa (Oncidiinae, Orchidaceae) from inselbergs in Brazilian caatinga: morphological and karyological evidence

Phytotaxa ◽  
2018 ◽  
Vol 374 (2) ◽  
pp. 147 ◽  
Author(s):  
JOEL M. P. CORDEIRO ◽  
FELIPE NOLLET ◽  
MARIA TERESA BURIL ◽  
MARK W. CHASE ◽  
LEONARDO P. FELIX
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Geographical Distribution ◽  
Related Species ◽  
Species Differences ◽  
Flower Morphology ◽  
Closely Related Species ◽  
Restricted Distribution ◽  
A New Species

We describe a new species of Gomesa (Oncidiinae, Orchidaceae), Gomesa caatingana, with restricted distribution on caatinga inselbergs in Paraíba and Pernambuco States, Brazil. Morphological and karyological characters of the new species were compared with those of Gomesa flexuosa, which is morphologically the most closely related species. Differences in geographical distribution, habit, flower morphology and chromosome number support description of this new species.

Étude caryologique de trois espèces d’Hypochoeris originaires d'Argentine : H. chillensis, H. microcephala var. albiflora et H. megapotamica

1994 ◽  
Vol 72 (10) ◽  
pp. 1496-1502 ◽  
Author(s):  
S. Siljak-Yakovlev ◽  
A. Bartoli ◽  
G. Roitman ◽  
N. Barghi ◽  
C. Mugnier
Keyword(s):  
Chromosome Number ◽  
Related Species ◽  
Secondary Constriction ◽  
Nucleolar Organizer ◽  
Asymmetry Index ◽  
Evolutionary Trend ◽  
Closely Related Species ◽  
Nucleolar Organizers ◽  
Morphological Differences ◽  
Secondary Constrictions

Three Hypochoeris species from Argentina with the same chromosome number (x = 4) and similar karyotypes (typically bimodal) show significant ecological and morphological differences. Comparative cytogenetic analysis was done for these taxa, producing karyotypes with correlated idiograms. The number of secondary constrictions and nucleolar organizers varied. The results from this study are discussed in terms of the mechanisms of microevolution within this group of closely related species, and in terms of the evolutionary trend in the genus and in the tribe Cichorieae. Key words: Hypochoeris, Cichorieae, bimodal karyotype, secondary constriction, nucleolar organizer, asymmetry index.

A new species of Trigonella sect. Ellipticae (Leguminosae-Papilionoideae) from Iran, including cytogenetic and anatomical notes

Phytotaxa ◽  
2015 ◽  
Vol 202 (1) ◽  
pp. 26 ◽  
Author(s):  
Massoud Ranjbar ◽  
ZAHRA HAJMORADI
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Related Species ◽  
Somatic Chromosome ◽  
Base Number ◽  
Somatic Chromosome Number ◽  
Chromosome Counts ◽  
Closely Related Species ◽  
A New Species

A new species, Trigonella bakhtiarica, from the Iranian province Chahar Mahal Va Bakhtiari is described, illustrated and compared to its most closely related species, T. aphanoneura. Trigonella bakhtiarica has a longer corolla and differs in the shape, surface and size of its pods, which are taxonomically informative characters in Trigonella sect. Ellipticae. Chromosome counts and meiosis assays show that both species are diploid, and that their euploid plants possess a somatic chromosome number of 2n = 2x = 16, which is consistent with the predicted base number of x = 8.

A clarification of Medicago sinskiae

1991 ◽  
Vol 69 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Ernest Small ◽  
Brenda Brookes
Keyword(s):  
Chromosome Number ◽  
Key Words ◽  
Related Species ◽  
The Other ◽  
Species Status ◽  
Closely Related Species

Little information has been available to justify the species status of the rare Turkmenian Medicago sinskiae Uljan. recognized by Uljanova in 1964. The holotype and plants raised from its seeds were examined, the chromosome number was determined, and a numerical taxonomic comparison was made of M. sinskiae and the other 12 species of Medicago section Spirocarpos subsection Pachyspirae. It was found that M. sinskiae is well separated from the most closely related species of Medicago and deserves recognition at the rank of species. Key words: Medicago sinskiae, Leguminoseae, alfalfa, taxonomy.

Centaurea stuessyi (Compositae: Cardueae), a new species from the eastern Iberian Peninsula

Phytotaxa ◽  
2013 ◽  
Vol 115 (2) ◽  
pp. 42 ◽  
Author(s):  
ITZIAR ARNELAS ◽  
JUAN ANTONIO DEVESA ◽  
EUSEBIO LÓPEZ
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Iberian Peninsula ◽  
Related Species ◽  
Ecological Preferences ◽  
A New Species

Centaurea stuessyi is described as new to science from the eastern Iberian Peninsula, Spain. The range of this new species coincides with the zone of overlap of the ranges of two related species, C. antennata (subsp. antennata) and C. linifolia. The chromosome number found in the new species (2n = 44) reinforces its differences from C. linifolia (2n = 22) and C. antennata (2n = 22). The new species is compared with related species, and a description is given of its ecological preferences.

Cytotaxonomic studies of Draba species of Canada and Alaska: D. ventosa, D. ruaxes, and D. paysonii

1971 ◽  
Vol 49 (8) ◽  
pp. 1455-1460 ◽  
Author(s):  
Gerald A. Mulligan
Keyword(s):  
North America ◽  
Chromosome Number ◽  
Related Species ◽  
Basic Chromosome Number ◽  
Base Number ◽  
Western North America ◽  
Closely Related Species ◽  
Basic Chromosome ◽  
Hexaploid Species

The cytotaxonomy of three closely related species of Draba, of the mountains of western North America, is discussed and a key is given: D. ventosa A. Gray (2n = 36), D. ruaxes Payson & St. John (2n = ca. 72), and D. paysonii Macbride (2n = 42). Evidence is presented demonstrating that D. ventosa and D. paysonii are triploids reproducing by agamospermy whereas the hexaploid species D. ruaxes is a sexual outcrosser. The former two species produce seed apomictically without any pollen stimulation. Draba ventosa and D. ruaxes have the basic chromosome number x = 12 and D. paysonii has the base number x = 14.

CHROMOSOME NUMBER POLYMORPHISM IN AN AUSTRALIAN PONERINE ANT

1969 ◽  
Vol 11 (2) ◽  
pp. 333-339 ◽  
Author(s):  
R. H. Crozier
Keyword(s):  
Chromosome Number ◽  
Sibling Species ◽  
Related Species ◽  
Ponerine Ant ◽  
Robertsonian System

Southern Victorian populations of Rhytidoponera metallica have n = 22 to 17, with progressive replacement of two acrocentrics at a time by a metacentric to yield numbers lower than 22 (nombre fondamentale = 23). A further collection with n = 12 represents either a further reduction in this Robertsonian system or a sibling species. Related species have n = 21 (victoriae) and 23 (tasmaniensis).

scholarly journals Centromere-mediated chromosome break drives karyotype evolution in closely related Malassezia species

2019 ◽  
Author(s):  
Sundar Ram Sankaranarayanan ◽  
Giuseppe Ianiri ◽  
Md. Hashim Reza ◽  
Bhagya C. Thimmappa ◽  
Promit Ganguly ◽  
...  
Keyword(s):  
Biological Sciences ◽  
Chromosome Number ◽  
Related Species ◽  
Chromosome Breakage ◽  
Sequence Motif ◽  
Chromosome Break ◽  
Closely Related Species ◽  
Malassezia Species ◽  
Synteny Blocks ◽  
Plausible Mechanism

AbstractIntra-chromosomal or inter-chromosomal genomic rearrangements often lead to speciation (1). Loss or gain of a centromere leads to alterations in chromosome number in closely related species. Thus, centromeres can enable tracing the path of evolution from the ancestral to a derived state (2). The Malassezia species complex of the phylum Basiodiomycota shows remarkable diversity in chromosome number ranging between six and nine chromosomes (3–5). To understand these transitions, we experimentally identified all eight centromeres as binding sites of an evolutionarily conserved outer kinetochore protein Mis12/Mtw1 in M. sympodialis. The 3 to 5 kb centromere regions share an AT-rich, poorly transcribed core region enriched with a 12 bp consensus motif. We also mapped nine such AT-rich centromeres in M. globosa and the related species Malassezia restricta and Malassezia slooffiae. While eight predicted centromeres were found within conserved synteny blocks between these species and M. sympodialis, the remaining centromere in M. globosa (MgCEN2) or its orthologous centromere in M. slooffiae (MslCEN4) and M. restricta (MreCEN8) mapped to a synteny breakpoint compared with M. sympodialis. Taken together, we provide evidence that breakage and loss of a centromere (CEN2) in an ancestral Malassezia species possessing nine chromosomes resulted in fewer chromosomes in M. sympodialis. Strikingly, the predicted centromeres of all closely related Malassezia species map to an AT-rich core on each chromosome that also shows enrichment of the 12 bp sequence motif. We propose that centromeres are fragile AT-rich sites driving karyotype diversity through breakage and inactivation in these and other species.Significance statementThe number of chromosomes can vary between closely related species. Centromere loss destabilizes chromosomes and results in reduced number of chromosomes to drive speciation. A series of evidence from studies on various cancers suggest that an imbalance in kinetochore-microtubule attachments results in breaks at the centromeres. To understand if such events can cause chromosome number changes in nature, we studied six species of Malassezia, of which three possess eight chromosomes and others have nine chromosomes each. We find signatures of chromosome breakage at the centromeres in organisms having nine chromosomes. We propose that the break at the centromere followed by fusions of acentric chromosomes to other chromosomes could be a plausible mechanism shaping the karyotype of Malassezia and related organisms.ClassificationBiological sciences, Genetics

Allium pseudotelmatum (Amaryllidaceae), a new species of Allium sect. Codonoprasum from Croatia

Phytotaxa ◽  
2017 ◽  
Vol 311 (2) ◽  
pp. 139
Author(s):  
MICHAELA JANDOVÁ ◽  
MARTINA OULEHLOVÁ ◽  
KATEŘINA VOJTĚCHOVÁ ◽  
MILOSLAV KITNER ◽  
MARTIN DUCHOSLAV
Keyword(s):  
New Species ◽  
Chromosome Number ◽  
Leaf Anatomy ◽  
Related Species ◽  
Chromosome Complement ◽  
Late Summer ◽  
Morphological Characters ◽  
Moist Soil ◽  
Citrus Orchards ◽  
A New Species

Allium pseudotelmatum, a new species of A. sect. Codonoprasum, is described from the southern Dalmatia (Croatia). It is a late-summer flowering species with pentaploid (2n = 40) chromosome complement, occurring in synanthropic habitats (Citrus orchards with nutrient rich and fresh moist soil). Karyology, leaf anatomy, morphology, ecology, molecular (ITS) and taxonomic relationships with related species are examined for the species. It shows morphological relationships with the northern Dalmatian species A. telmatum from which it well differentiates for many morphological characters including the presence of aerial bulbils within the inflorescence, phenology, chromosome number and ecology. Confusion of A. pseudotelmatum with some specimens of A. oleraceum due to the presence of bulbils within the inflorescence is discussed.

scholarly journals Functional and Comparative Analysis of Centromeres Reveals Clade-Specific Genome Rearrangements in Candida auris and a Chromosome Number Change in Related Species

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Aswathy Narayanan ◽  
Rakesh Netha Vadnala ◽  
Promit Ganguly ◽  
Pavitra Selvakumar ◽  
Shivaprakash M. Rudramurthy ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Related Species ◽  
Chromosomal Rearrangements ◽  
Pathogenic Fungi ◽  
Multidrug Resistant ◽  
Comparative Genomic ◽  
Candida Auris ◽  
Evolutionary Trajectory ◽  
Content Type ◽  
Centromere Inactivation

ABSTRACT The thermotolerant multidrug-resistant ascomycete Candida auris rapidly emerged since 2009 causing systemic infections worldwide and simultaneously evolved in different geographical zones. The molecular events that orchestrated this sudden emergence of the killer fungus remain mostly elusive. Here, we identify centromeres in C. auris and related species, using a combined approach of chromatin immunoprecipitation and comparative genomic analyses. We find that C. auris and multiple other species in the Clavispora/Candida clade shared a conserved small regional GC-poor centromere landscape lacking pericentromeres or repeats. Further, a centromere inactivation event led to karyotypic alterations in this species complex. Interspecies genome analysis identified several structural chromosomal changes around centromeres. In addition, centromeres are found to be rapidly evolving loci among the different geographical clades of the same species of C. auris. Finally, we reveal an evolutionary trajectory of the unique karyotype associated with clade 2 that consists of the drug-susceptible isolates of C. auris. IMPORTANCE Candida auris, the killer fungus, emerged as different geographical clades, exhibiting multidrug resistance and high karyotype plasticity. Chromosomal rearrangements are known to play key roles in the emergence of new species, virulence, and drug resistance in pathogenic fungi. Centromeres, the genomic loci where microtubules attach to separate the sister chromatids during cell division, are known to be hot spots of breaks and downstream rearrangements. We identified the centromeres in C. auris and related species to study their involvement in the evolution and karyotype diversity reported in C. auris. We report conserved centromere features in 10 related species and trace the events that occurred at the centromeres during evolution. We reveal a centromere inactivation-mediated chromosome number change in these closely related species. We also observe that one of the geographical clades, the East Asian clade, evolved along a unique trajectory, compared to the other clades and related species.

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