Parana y Los Claveles

Garupá, Argentina

Parana y Los Claveles

Garupá, Argentina
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Martinez P.A.,Federal University of Rio Grande do Norte | Martinez P.A.,Rey Juan Carlos University | Zurano J.P.,Federal University of Rio Grande do Norte | Zurano J.P.,Federal University of Paraiba | And 6 more authors.
Molecular Phylogenetics and Evolution | Year: 2015

Tropical reef fishes show contrasting patterns of karyotypic diversity. Some families have a high chromosomal conservatism while others show wide variation in karyotypic macrostructure. However, the influence of life-history traits on karyotypic diversity is largely unknown. Using phylogenetic comparative methods, we assessed the effects of larval and adult species traits on chromosomal diversity rates of 280 reef species in 24 families. We employed a novel approach to account for trait variation within families as well as phylogenetic uncertainties. We found a strong negative relationship between karyotypic diversity rates and body size and depth range. These results suggest that lineages with higher dispersal potential and gene flow possess lower karyotypic diversity. Taken together, these results provide evidence that biological traits might modulate the rate of karyotypic diversity in tropical reef fishes. © 2015 Elsevier Inc.

Baldo D.,Institute Herpetologia | Baldo D.,National University of Misiones | Cotichelli L.,National University of Misiones | Pereyra M.O.,Museo Argentino de Ciencias Naturales Bernardino Rivadavia | And 7 more authors.
Journal of Herpetology | Year: 2012

We present a cytogenetic survey of the basal bufonid genus Melanophryniscus that covered 14 of the 25 species currently recognized, representing the three phenetic species groups: M. moreirae, M. stelzneri, and M. tumifrons. All species presented a diploid chromosome complement constituted by 11 bi-armed chromosome pairs (2n = 2x = 22; FN = 44). Some remarkable differences were observed between species groups: chromosome pair 4 was metacentric in species of the M. tumifrons group (also with a distinctive C-positive block) but submetacentric in the M. stelzneri group and M. sanmartini (M. moreirae group); pair 5 was submetacentric in M. sanmartini and metacentric in the rest. Chromosome secondary constrictions and silver-stained nucleolar organizer regions were located either in pair 5, 7, or 8 in the M. tumifrons group, M. sanmartini and M. krauczuki (M. stelzneri group), and M. stelzneri group, respectively; and pair 7 was relatively larger in M. sanmartini and M. krauczuki. Studied cytogenetic characters support the M. tumifrons group and suggest a close relationship between M. krauczuki and M. sanmartini. These results call for a reassessment of species relations within Melanophryniscus under an inclusive phylogenetic study. © 2012 Society for the Study of Amphibians and Reptiles.

Castillo E.R.D.,National University of Misiones | Taffarel A.,National University of Misiones | Mariottini Y.,CONICET | Fernandez-Arhex V.,CONICET | And 2 more authors.
Zoological Science | Year: 2016

South American melanopline grasshoppers display a disproportionate number of derived karyotypes, including many cases of neo-sex chromosome systems. This is especially true of the genus Dichroplus and its Maculipennis species group. We analyzed the karyotype and neo-sex chromosomes in mitosis and meiosis of Dichroplus maculipennis and D. vittigerum from Argentina using conventional and fluorescent cytogenetic protocols in order to elucidate the behavior and origin of these neo-XY systems in relation to the current phylogeny of this group. Our results showed that D. maculipennis (2n = 22♂/22♀; neoXY/neoXX) and D. vittigerum, whose karyotype is described here for the first time (2n = 18♂/18♀; neoXY/neoXX), show highly evolved neo-XY systems, although with significant differences between them. Furthermore, both species differ for two autosomal fixed Robertsonian fusions present in D. vittigerum. Analysis of karyotypic character state optimization strongly suggests the independent origin and evolution of neo-sex systems within this species group. © 2016 Zoological Society of Japan.

Bidau C.J.,Parana Y Los Claveles | Marti D.A.,National University of Misiones
Journal of Orthoptera Research | Year: 2010

The history of the study of orthopteran chromosomes is coincident with the formulation of the chromosome theory of heredity and the rediscovery of Mendel's laws, thus with the birth of cytogenetics. We review the early contributions of grasshopper chromosomes to the chromosome theory the understanding of sex chromosomes, the phenomena of mitosis, meiosis, linkage, crossing over and recombination, the problems of chiasma localization and terminalization, reproduction and parthenogenesis, the nature and behavior of B chromosomes and supernumerary segments, and the role of chromosomal rearrangements in microevolution and speciation. We also discuss the influence of early works on later research, and emphasize the fundamental contributions of Michael J. D.White to modern cytogenetics and evolutionary biology in general.

Castillo E.R.,National University of Misiones | Marti D.A.,CONICET | Bidau C.J.,Parana Y Los Claveles
Journal of Orthoptera Research | Year: 2010

We review historical and pioneering work as well as recently published papers about orthopteran sex chromosomes and neo-sex mechanisms, highlighting Michael White's significant contributions. Meiotic research in Orthoptera in the early twentieth century was central to confirming that sex determination had a chromosomal basis: the study of sex chromosomes produced fundamental support to the chromosome theory of heredity. We also explore recent theoretical models of sex-chromosome evolution and consider the possible causes of crossing over restriction in proto-sex chromosomes, as well as the progressive differentiation (erosion and degeneration) of the Y chromosome in neo-chromosome systems in different taxa. We discuss neo-XY and neo-X1X2Y chromosome systems of South American Melanoplinae (Acrididae) as potential experimental models to study steps in sex-chromosome evolution because these systems fall within a continuum of evolutionary stages, some of them recently established. We also provide an explanation for the disproportionate frequency of neo-sex systems and Robertsonian-derived karyotypes in Neotropical Melanoplinae, based on the centromeric drive theory, and propose that Neotropical melanoplines' high karyotypic diversity supports an ancient South American origin of the subfamily. We discuss the hypothesis that neo-sex chromosome systems produce favorable new linkage relationships between genes in the X and the involved autosome, some of which could be sex determination related, creating a new balance between sex chromosomes and autosomes. We also review Mesa's hypothesis that, based on the observed fact that no major taxon of orthopterans shows neo-sex chromosomal mechanisms in all their species, the acquisition of a neo-sex chromosome system could condemn species of grasshoppers to a short evolutionary career. Little is yet known about the role of neo-Y chromosomes in Orthoptera, thus mostly speculative explanations about neo-sex chromosome function can be made at present. New studies with modern molecular techniques are needed to understand chromosomal sex determination in Orthoptera, which could in turn help explain the role of new chromosomal sex systems in grasshopper species.

Bidau C.J.,Parana y Los Claveles | Marti D.A.,National University of Misiones | Marti D.A.,CONICET
European Journal of Entomology | Year: 2013

We discuss and criticise the contention of Colombo (2012) that the central-marginal model does not apply to three species of chromosomally polymorphic acridid grasshoppers, and that chromosomal clines in these species are a consequence of temperature gradients. We also discuss Colombo's interpretation of our own results on the South American melanopline grasshopper, Dichroplus pratensis Bruner.

PubMed | Federal University of Alagoas, Rey Juan Carlos University, Federal University of Sergipe, Parana y Los Claveles and 2 more.
Type: | Journal: Heredity | Year: 2016

Chromosomal rearrangements have a relevant role in organismic evolution. However, little is known about the mechanisms that lead different phylogenetic clades to have different chromosomal rearrangement rates. Here, we investigate the causes behind the wide karyotypic diversity exhibited by mammals. In particular, we analyzed the role of metabolic, reproductive, biogeographic and genomic characteristics on the rates of macro- and microstructural karyotypic diversification (rKD) using comparative phylogenetic methods. We found evidence that reproductive characteristics such as larger litter size per year and longevity, by allowing a higher number of meioses in absolute time, favor a higher probability of chromosomal change. Furthermore, families with large geographic distributions but containing species with restricted geographic ranges showed a greater probability of fixation of macrostructural chromosomal changes in different geographic areas. Finally, rKD does not evolve by Brownian motion because the mutation rate depends on the concerted evolution of repetitive sequences. The decisive factors of rKD evolution will be natural selection, genetic drift and meiotic drive that will eventually allow or not the fixation of the rearrangements. Our results indicate that mammalian karyotypic diversity is influenced by historical and adaptive mechanisms where reproductive and genomic factors modulate the rate of chromosomal change.Heredity advance online publication, 2 November 2016; doi:10.1038/hdy.2016.110.

Martinez P.A.,Federal University of Rio Grande do Norte | Bidau C.J.,Parana y los Claveles
Mammalian Biology | Year: 2016

Sexual size dimorphism (SSD) is affected by a large number of factors, mating system being one of the most relevant. Almost 70 species of subterranean rodents of the genus Ctenomys are considered highly polygynic, and polygyny jointly with absence of paternal care of the young, favours high SSD. In this respect, Rensch's rule predicts that SSD scales with body size so that when males are larger than females SSD tends to increase with body size. We studied SSD and Rensch's rule in 28 taxa of Ctenomys using a phylogenetic approach employing the method of phylogenetic reduced major axis (pRMA) to perform reduced major axis (RMA) model II regression in the form of log 10(male mass) on log. 10(female mass). The RMA regression slope (β) was statistically tested to accept or reject the null hypothesis that βpRMA = 1.0. A slope significantly >1.0 would signal concordance with Rensch's rule. Our results showed that despite a high degree of male-biased SSD as expected from polygynic species, Rensch's rule is not verified in this rodent group. The causes of the non-concordance with Rensch's rule as well as its taxonomic level of application are discussed in terms of current models of SSD. © 2014 Deutsche Gesellschaft für Säugetierkunde.

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