Chromosome studies in species of Eugenia, Myrciaria and Plinia (Myrtaceae) from south-eastern Brazil

2006 ◽  
Vol 54 (4) ◽  
pp. 409 ◽  
Author(s):  
Itayguara Ribeiro da Costa ◽  
Eliana Regina Forni-Martins
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosomal Evolution ◽  
South Eastern ◽  
Brazilian Species ◽  
Eastern Brazil

The chromosome numbers of Brazilian species of Myrtaceae were reassessed in the context of chromosomal evolution in fleshy-fruited Myrteae. The chromosome numbers of 14 species of Eugenia, three of Myrciaria and two of Plinia were determined, 14 of which had not been published before. In Eugenia, a diploid state (2n = 22) was found in nine species, polyploid (2n = 33 or 2n = 44) in three species, and both diploid and polyploid cytotypes in another three species. The percentage of Eugenia species with a known chromosome number increased from 19 to 31 species, 22.6% of which were polyploid (3 triploid, 1 tetraploid and 3 hexaploid) and a further 16.1% either dysploid from the triploid level or had both diploid and polyploid races, giving a total of 38.7% in which polyploidy is recorded. In Myrciaria (3 species) and Plinia (2 species), the chromosome number was 2n = 22, with no polyploidy known in these genera. The results reinforce the previous indications that polyploidy is of great importance in the evolution of fleshy-fruited Myrteae.

Karyotypes of Leptarrhena and Tanakaea (Saxifragaceae)

1984 ◽  
Vol 62 (4) ◽  
pp. 671-673 ◽  
Author(s):  
Douglas E. Soltis
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosomal Evolution ◽  
Conservative Nature ◽  
Chromosomal Data ◽  
Base Chromosome Number ◽  
Flavonoid Chemistry

In an attempt to clarify subtribal relationships in tribe Saxifrageae, chromosome numbers and karyotypes were determined for the two species comprising subtribe Leptarrheninae: Leptarrhena pyrolifolia and Tanakaea radicans. In both species 2n = 14, a common chromosome number throughout Saxifrageae. The two species have distinctive karyotypes that appear to differ in the centromeric positions of three pairs of chromosomes. These findings, in conjunction with earlier studies, demonstrate that genera of Saxifrageae often differ karyotypically. Leptarrhena exhibits considerable karyotypic similarity to genera of subtribe Saxifraginae characterized by a base chromosome number of x = 7. Chromosomal data, therefore, do not clearly differentiate subtribes Saxifraginae and Leptarrheninae. This observation is in agreement with evidence from paly-nology and flavonoid chemistry. Karyotypic studies continue to demonstrate the conservative nature of chromosomal evolution in tribe Saxifrageae.

Phylogenetics and chromosomal evolution in the Poaceae (grasses)

2004 ◽  
Vol 52 (1) ◽  
pp. 13 ◽  
Author(s):  
Khidir W. Hilu
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosome Doubling ◽  
Chromosomal Evolution ◽  
Basic Chromosome Number ◽  
Basic Chromosome ◽  
Wide Range ◽  
The Family

The wide range in basic chromosome number (x = 2–18) and prevalence of polyploidy and hybridisation have resulted in contrasting views on chromosomal evolution in Poaceae. This study uses information on grass chromosome number and a consensus phylogeny to determine patterns of chromosomal evolution in the family. A chromosomal parsimony hypothesis is proposed that underscores (1) the evolution of the Joinvilleaceae/Ecdeiocoleaceae/Poaceae lineage from Restionaceae ancestors with x = 9, (2) aneuploid origin of x�=�11 in Ecdeiocoleaceae and Poaceae (Streptochaeta, Anomochlooideae), (3) reduction to x = 9, followed by chromosome doubling within Anomochlooideae to generate the x = 18 in Anomochloa, and (4) aneuploid increase from the ancestral x = 11 to x = 12 in Pharoideae and Puelioideae, and further diversification in remaining taxa (Fig. 3b). Higher basic chromosome numbers are maintained in basal taxa of all grass subfamilies, whereas smaller numbers are found in terminal species. This finding refutes the 'secondary polyploidy hypothesis', but partially supports the 'reduction hypothesis' previously proposed for chromosomal evolution in the Poaceae.

scholarly journals Genome Size and Chromosome Number Evolution in Korean Iris L. Species (Iridaceae Juss.)

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1284 ◽  
Author(s):  
Bokyung Choi ◽  
Hanna Weiss-Schneeweiss ◽  
Eva M. Temsch ◽  
Soonku So ◽  
Hyeon-Ho Myeong ◽  
...  
Keyword(s):  
Chromosome Number ◽  
Genome Size ◽  
Chromosome Numbers ◽  
Size Variation ◽  
Chromosomal Evolution ◽  
Genome Size Variation ◽  
Molecular Cytogenetic ◽  
Chromosome Number Evolution ◽  
Phylogenetic Framework ◽  
Phylogenomic Analyses

Chromosome numbers, karyotypes, and genome sizes of 14 Iris L. (Iridaceae Juss.) species in Korea and their closely related taxon, Sisyrinchium rosulatum, are presented and analyzed in a phylogenetic framework. To date, understanding the chromosomal evolution of Korean irises has been hampered by their high chromosome numbers. Here, we report analyses of chromosome numbers and karyotypes obtained via classic Feulgen staining and genome sizes measured using flow cytometry in Korean irises. More than a two-fold variation in chromosome numbers (2n = 22 to 2n = 50) and over a three-fold genome size variation (2.39 pg to 7.86 pg/1 C) suggest the putative polyploid and/or dysploid origin of some taxa. Our study demonstrates that the patterns of genome size variation and chromosome number changes in Korean irises do not correlate with the phylogenetic relationships and could have been affected by different evolutionary processes involving polyploidy or dysploidy. This study presents the first comprehensive chromosomal and genome size data for Korean Iris species. Further studies involving molecular cytogenetic and phylogenomic analyses are needed to interpret the mechanisms involved in the origin of chromosomal variation in the Iris.

Karyotypic diversification and its contribution to the taxonomy of Eleocharis (Cyperaceae) from Brazil

2010 ◽  
Vol 58 (1) ◽  
pp. 49 ◽  
Author(s):  
Carlos Roberto Maximiano da Silva ◽  
Rafael Trevisan ◽  
Maria Socorro González-Elizondo ◽  
Josué Maldonado Ferreira ◽  
André Luís Laforga Vanzela
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Karyotype Analysis ◽  
Basic Number ◽  
Common Event ◽  
Brazilian Species ◽  
Bivalent Formation ◽  
Chromosome Fission ◽  
Regular Meiosis

A karyotype analysis of 147 populations of 25 Brazilian species of Eleocharis (Cyperaceae) was carried out, including representatives of the three subgenera that occur in the country: Limnochloa, Scirpidium and Eleocharis. The analyses showed chromosomes without centromeres, but with terminal nucleolar constrictions (satellites) in some chromosomes. The chromosome numbers varied from 2n = 6 in E. subarticulata and E. maculosa to 2n = 60 in E. laeviglumis, but the chromosome basic number x = 5 was confirmed. Species of the subgenera Eleocharis and Scirpidium possess fewer and larger chromosomes, while those in the subgenus Limnochloa have small and more numerous chromosomes. These features indicate that the karyotypes of the subgenera Eleocharis and Scirpidium are more closely related, in agreement with morphological and phylogenetical data. The representatives of the section Eleocharis exhibited the largest differences in chromosome number and size, probably due to chromosome fission and fusion. Polyploidy was the most common event in this group. Nevertheless, most of the studied species exhibited regular meiosis with only bivalent formation, even the polyploids, such as in E. geniculata and E. sellowiana. The cytogenetic information obtained showed quite variable karyotypes with chromosomes gradually decreasing in size, and predominance of polyploidy. These results are useful in the differentiation of the subgenera.

scholarly journals A new species ofEugenia(Myrtaceae) from south-eastern Brazil

2008 ◽  
Vol 158 (2) ◽  
pp. 306-308
Author(s):  
MARCELO DA COSTA SOUZA ◽  
MARLI PIRES MORIM
Keyword(s):  
New Species ◽  
South Eastern ◽  
Eastern Brazil ◽  
A New Species

scholarly journals Regionally extinct species rediscovered: the bush dog Speothos venaticus in Minas Gerais, south-eastern Brazil

Oryx ◽  
2014 ◽  
Vol 49 (1) ◽  
pp. 60-63 ◽  
Author(s):  
Guilherme Braga Ferreira ◽  
Marcelo Juliano Rabelo Oliveira ◽  
Rogério Cunha de Paula ◽  
Flávio Henrique Guimarães Rodrigues ◽  
Érica Daniele Cunha Carmo
Keyword(s):  
Protected Areas ◽  
Minas Gerais ◽  
The State ◽  
South American ◽  
North West ◽  
South Eastern ◽  
The North ◽  
Eastern Brazil ◽  
Bush Dog ◽  
Speothos Venaticus

AbstractThe bush dog Speothos venaticus, a rare Near Threatened South American canid that lives in packs, was thought to be extinct in Minas Gerais state, south-eastern Brazil, until recently. Here, we report four recent records of the species in Minas Gerais, the first in the state since the description of the species in 1842. All records are from the Cerrado ecosystem in the north and north-west of the state; two are from animals found dead, one from footprints and another from a camera trap. Three of the records were inside or close (< 10 km) to strict protected areas, in a region recognized as the Protected Areas Mosaic Sertão Veredas–Peruaçu, where we expect any new records of the bush dog to be found. We discuss the low probability of detecting the bush dog and the main regional threats to the species, and emphasize the need to protect large and interconnected natural areas and keep them free of domestic dogs to avoid the extinction of the bush dog in Minas Gerais.

Population biology and diet of the puffer fish Lagocephalus laevigatus (Tetraodontiformes: Tetraodontidae) in Caraguatatuba Bay, south-eastern Brazil

2011 ◽  
Vol 92 (2) ◽  
pp. 407-412 ◽  
Author(s):  
M.R. Denadai ◽  
F.B. Santos ◽  
E. Bessa ◽  
L.P. Bernardes ◽  
A. Turra
Keyword(s):  
Population Biology ◽  
Temporal Distribution ◽  
Late Winter ◽  
Entire Study Period ◽  
Entire Study ◽  
South Eastern ◽  
Eastern Brazil ◽  
Puffer Fish ◽  
Spatio Temporal ◽  
Sexually Mature

This study describes the spatio-temporal distribution, population biology, and diet of the puffer fish Lagocephalus laevigatus in Caraguatatuba Bay, south-eastern Brazil. Monthly samples were taken between August 2003 and October 2004 by trawls in two areas, south and north, at depths of 1 to 4 m. The fish were measured and their sex and reproductive stage determined. The abundance of this species was compared between areas and among months, and the items in the diet were identified and quantified. Lagocephalus laevigatus was rare in Caraguatatuba Bay, where only 199 small individuals (4.8 to 15.4 cm) were obtained in the entire study period, suggesting that this species uses the estuary as a nursery. None of the specimens of L. laevigatus captured in Caraguatatuba Bay were sexually mature. Higher densities of L. laevigatus in the bay were recorded in the south area and between October and December 2003, i.e. in the spring, suggesting that spawning may occur from late winter to spring (August through to November). The diet items consumed by L. laevigatus in Caraguatatuba Bay were, as expected from the current literature, crustaceans, mainly amphipods, and fish. However, the most-consumed item was the sea whip Leptogorgia setacea (Cnidaria). This feeding habit may be related to the presence of toxins (tetrodotoxin and saxitoxin) that are frequently found in the skin and viscera of L. laevigatus, which may be sequestered from the sea whip, which possibility still needs to be specifically evaluated.

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