Karyological study of Amphisbaena ridleyi (Squamata, Amphisbaenidae), an endemic species of the Archipelago of Fernando de Noronha, Pernambuco, Brazil

The karyotype of Amphisbaena ridleyi, an endemic species of the archipelago of Fernando de Noronha, in State of Pernambuco, Brazil, is described after conventional staining, Ag-NOR impregnation and fluorescence in situ hybridization (FISH) with a telomeric probe. The diploid number is 46, with nine pairs of macrochromosomes (three metacentrics, four subtelocentrics and two acrocentrics) and 14 pairs of microchromosomes. The Ag-NOR is located in the telomeric region of the long arm of metacentric chromosome 2 and FISH revealed signals only in the telomeric region of all chromosomes. Further cytogenetic data on other amphisbaenians as well as a robust phylogenetic hypothesis of this clade is needed in order to understand the evolutionary changes on amphisbaenian karyotypes.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)CNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Demographic processes in the montane Atlantic rainforest: Molecular and cytogenetic evidence from the endemic frog Proceratophrys boiei

Historical climatic refugia predict genetic diversity in lowland endemics of the Brazilian Atlantic rainforest. Yet, available data reveal distinct biological responses to the Last Glacial Maximum (LGM) conditions across species of different altitudinal ranges. We show that species occupying Brazil's montane forests were significantly less affected by LGM conditions relative to lowland specialists, but that pre-Pleistocene tectonics greatly influenced their geographic variation. Our conclusions are based on palaeoclimatic distribution models, molecular sequences of the cytochrome b, 16S, and RAG-1 genes, and karyotype data for the endemic frog Proceratophrys boiei. DNA and chromosomal data identify in P. boiei at least two broadly divergent phylogroups, which have not been distinguished morphologically. Cytogenetic results also indicate an area of hybridization in southern Sao Paulo. The location of the phylogeographic break broadly matches the location of a NW-SE fault, which underwent reactivation in the Neogene and led to remarkable landscape changes in southeastern Brazil. Our results point to different mechanisms underpinning diversity patterns in lowland versus montane tropical taxa, and help us to understand the processes responsible for the large number of narrow endemics currently observed in montane areas of the southern Atlantic forest hotspot. (C) 2011 Elsevier Inc. All rights reserved.Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Pesquisa e Desenvolvimento (CNPq)Conselho Nacional de Pesquisa e Desenvolvimento (CNPq)National Science FoundationNational Science Foundation [DEB 0817035, DEB 1120487]Microsoft CorporationMicrosoft Corporatio

Karyotypes of Eight Species of \u3cem\u3eLeptodactylus\u3c/em\u3e (Anura, Leptodactylidae) with a Description of a New Karyotype for the Genus

Karyotypes of eight species of Leptodactylus (Anura, Leptodactylidae) with a description of a new karyotype for the genus. Eight species of the Neotropical genus Leptodactylus were karyologically studied: seven of them (L. gracilis, L. mystacinus, L. petersii, L. pustulatus, L. macrosternum, L. ocellatus, L. labyrinthicus) presented 2n=22 and L. silvanimbus showed a distinctive karyotype with 2n=24. Nucleolar organizer regions (Ag-NORs) were detected in two different pairs of chromosomes: pair 4 at the proximal region of the long arm of one individual of L. mystacinus from São Paulo state and of L. petersii; and pair 8 of all other species (located terminally at the short arm of L. silvanimbus, L. ocellatus, L. macrosternum, L. pustulatus, and L. labyrinthicus; interstitially at the short arm in L. gracilis; and at the long arm in L. mystacinus from Mato Grosso state). The diploid number reported here for L. silvanimbus shared with Scythrophrys and Paratelmatobius could represent the ancestral chromosome number for Leptodactylus (sensu Frost et al. 2006); in this case the 2n=22 karyotypes would then represent the derivative condition for the genus. Nevertheless, the distinctive karyotype of L. silvanimbus lead us to preclude a final decision on its relationships. Additional studies including morphological and molecular approaches are needed in order to clarify the phylogenetic position of L. silvanimbus

Karyotypes of eight species of Leptodactylus (Anura, Leptodactylidae) with a description of a new karyotype for the genus

Eight species of the Neotropical genus Leptodactylus were karyologically studied: seven of them (L. gracilis, L. mystacinus, L. petersii, L. pustulatus, L. macrosternum, L. ocellatus, L. labyrinthicus) presented 2n=22 and L. silvanimbus showed a distinctive karyotype with 2n=24. Nucleolar organizer regions (Ag-NORs) were detected in two different pairs of chromosomes: pair 4 at the proximal region of the long arm of one individual of L. mystacinus from São Paulo state and of L. petersii; and pair 8 of all other species (located terminally at the short arm of L. silvanimbus, L. ocellatus, L. macrosternum, L. pustulatus, and L. labyrinthicus; interstitially at the short arm in L. gracilis; and at the long arm in L. mystacinus from Mato Grosso state). The diploid number reported here for L. silvanimbus shared with Scythrophrys and Paratelmatobius could represent the ancestral chromosome number for Leptodactylus (sensu Frost et al. 2006); in this case the 2n=22 karyotypes would then represent the derivative condition for the genus. Nevertheless, the distinctive karyotype of L. silvanimbus lead us to preclude a final decision on its relationships. Additional studies including morphological and molecular approaches are needed in order to clarify the phylogenetic position of L. silvanimbus

Karyotypes of eight species of Leptodactylus (Anura, Leptodactylidae) with a description of a new karyotype for the genus

Eight species of the Neotropical genus Leptodactylus were karyologically studied: seven of them (L. gracilis, L. mystacinus,L. petersii, L. pustulatus, L. macrosternum, L. ocellatus, L. labyrinthicus) presented 2n=22 and L. silvanimbus showed a distinctive karyotype with 2n=24. Nucleolar organizer regions (Ag-NORs) were detected in two different pairs of chromosomes: pair 4 at the proximal region of the long arm of one individual of L. mystacinus from São Paulo state and of L. petersii; and pair 8 of all other species (located terminally at the short arm of L. silvanimbus, L. ocellatus, L. macrosternum, L. pustulatus, and L. labyrinthicus; interstitially at the short arm in L. gracilis; and at the long arm in L. mystacinus from Mato Grosso state). The diploid number reported here for L. silvanimbus shared with Scythrophrys and Paratelmatobius could represent the ancestral chromosome number for Leptodactylus (sensu Frost et al. 2006); in this case the 2n=22 karyotypes would then represent the derivative condition for the genus. Nevertheless, the distinctive karyotype of L. silvanimbus lead us to preclude a final decision on its relationships. Additional studies including morphological and molecular approaches are needed in order to clarify the phylogenetic position of L. silvanimbus

The taxonomic status of the endangered thin-spined porcupine, Chaetomys subspinosus (Olfers, 1818), based on molecular and karyologic data

<p>Abstract</p> <p>Background</p> <p>The thin-spined porcupine, also known as the bristle-spined rat, <it>Chaetomys subspinosus </it>(Olfers, 1818), the only member of its genus, figures among Brazilian endangered species. In addition to being threatened, it is poorly known, and even its taxonomic status at the family level has long been controversial. The genus <it>Chaetomys </it>was originally regarded as a porcupine in the family Erethizontidae, but some authors classified it as a spiny-rat in the family Echimyidae. Although the dispute seems to be settled in favor of the erethizontid advocates, further discussion of its affinities should be based on a phylogenetic framework. In the present study, we used nucleotide-sequence data from the complete mitochondrial cytochrome <it>b </it>gene and karyotypic information to address this issue. Our molecular analyses included one individual of <it>Chaetomys subspinosus </it>from the state of Bahia in northeastern Brazil, and other hystricognaths.</p> <p>Results</p> <p>All topologies recovered in our molecular phylogenetic analyses strongly supported <it>Chaetomys subspinosus </it>as a sister clade of the erethizontids. Cytogenetically, <it>Chaetomys subspinosus </it>showed 2n = 52 and FN = 76. Although the sexual pair could not be identified, we assumed that the X chromosome is biarmed. The karyotype included 13 large to medium metacentric and submetacentric chromosome pairs, one small subtelocentric pair, and 12 small acrocentric pairs. The subtelocentric pair 14 had a terminal secondary constriction in the short arm, corresponding to the nucleolar organizer region (Ag-NOR), similar to the erethizontid <it>Sphiggurus villosus</it>, 2n = 42 and FN = 76, and different from the echimyids, in which the secondary constriction is interstitial.</p> <p>Conclusion</p> <p>Both molecular phylogenies and karyotypical evidence indicated that <it>Chaetomys </it>is closely related to the Erethizontidae rather than to the Echimyidae, although in a basal position relative to the rest of the Erethizontidae. The high levels of molecular and morphological divergence suggest that <it>Chaetomys </it>belongs to an early radiation of the Erethizontidae that may have occurred in the Early Miocene, and should be assigned to its own subfamily, the Chaetomyinae.</p

The phylogenetic position of the enigmatic Atlantic forest-endemic spiny mouse Abrawayaomys (Rodentia: Sigmodontinae)

Background The phylogenetic position of the sigmodontine genus Abrawayaomys, historically assigned to the tribe Thomasomyini or considered a sigmodontine incertae sedis, was assessed on the basis of nuclear and mitochondrial DNA sequences obtained from four individuals from different localities in the Atlantic forest of Brazil. Sequences of Abrawayaomys were analyzed in the context of broad taxonomic matrices by means of maximum-likelihood (ML) and Bayesian analyses (BA). Results The phylogenetic position of Abrawayaomys differed depending on the gene analyzed and the analysis performed (interphotoreceptor retinoid-binding protein (IRBP) ML: sister to Thomasomyini; IRBP BA: sister to Akodontini; cytochrome (Cyt) b ML: sister to Neotomys; and Cyt b BA: sister to Reithrodontini). With the sole exception of the BA based on Cyt b sequences, where the Abrawayaomys-Reithrodon clade had strong support, all sister-group relationships involving Abrawayaomys lacked any significant support. Conclusions As such, Abrawayaomys constitutes the only representative so far known of one of the main lineages of the sigmodontine radiation, differing from all other Atlantic forest sigmodontine rodents by having a unique combination of morphological character states. Therefore, in formal classifications, it should be regarded as a Sigmodontinae incertae sedis.Fil: Ventura, Karen. Universidade de São Paulo. Instituto de Biociências. Departamento de Genética e Biologia Evolutiva; BrasilFil: Silva, Maria José. Instituto Butantan. Laboratório de Ecologia e Evolução; BrasilFil: Geise, Lena. Universidade do Estado do Rio de Janeiro. Instituto de Biologia. Departamento de Zoologia. Laboratório de Mastozoologia; BrasilFil: Leite, Yuri L. R.. Universidade Federal Do Espirito Santo; BrasilFil: Pardiñas, Ulyses Francisco J.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Yonenaga Yassuda, Yatiyo. Universidade de São Paulo. Instituto de Biociências. Departamento de Genética e Biologia Evolutiva; BrasilFil: D Elía, Guillermo. Universidad Austral de Chile. Facultad de Ciencias. Instituto de Ciencias Ambientales y Evolutivas; Chil

Thaptomys Thomas 1915 (Rodentia, Sigmodontinae, Akodontini) with karyotypes 2n = 50, FN = 48, and 2n = 52, FN = 52: Two monophyletic lineages recovered by molecular phylogeny

A novel karyotype with 2n = 50, FN = 48, was described for specimens of Thaptomys collected at Una, State of Bahia, Brazil, which are morphologically indistinguishable from Thaptomys nigrita, 2n = 52, FN = 52, found in other localities. It was hence proposed that the 2n = 50 karyotype could belong to a distinct species, cryptic of Thaptomys nigrita, once chromosomal rearrangements observed, along with the geographic distance, might represent a reproductive barrier between both forms. Phylogenetic analyses using maximum parsimony and maximum likelihood based on partial cytochrome b sequences with 1077 bp were performed, attempting to establish the relationships among the individuals with distinct karyotypes along the geographic distribution of the genus; the sample comprised 18 karyotyped specimens of Thaptomys, encompassing 15 haplotypes, from eight different localities of the Atlantic Rainforest. The intra-generic relationships corroborated the distinct diploid numbers, once both phylogenetic reconstructions recovered two monophyletic lineages, a northeastern clade grouping the 2n = 50 and a southeastern clade with three subclades, grouping the 2n = 52 karyotype. The sequence divergence observed between their individuals ranged from 1.9% to 3.5%