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Diego Astúa - One of the best experts on this subject based on the ideXlab platform.
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Distribution extension and sympatric occurrence of Gracilinanus agilis and
2016Co-Authors: Lena Geise, Diego AstúaAbstract:G. microtarsus (Didelphimorphia, Didelphidae), with cytogenetic note
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Orbit orientation in didelphid marsupials (Didelphimorphia: Didelphidae).
Current zoology, 2016Co-Authors: Patricia Pilatti, Diego AstúaAbstract:Usually considered a morphologically conservative group, didelphid marsupials present considerable variation in ecology and body size, some of which were shown to relate to morphological structures. Thus, changes on orbit morphology are likely and could be related to that variation. We calculated orbit orientation in 873 specimens of 16 Didelphidae genera yielding estimates of orbits convergence (their position relative to midsagittal line) and verticality (their position relative to frontal plane). We then compared similarities in these variables across taxa to ecological, morphological and phylogenetic data to evaluate the influencing factors on orbit orientation in didelphids. We found an inverse relation between convergence and verticality. Didelphids orbits have low verticality but are highly convergent, yet orbit orientation differs significantly between taxa, and that variation is related to morphological aspects of the cranium. Rostral variables are the only morphological features correlated with orbit orientation: increasing snout length yields more convergent orbits, whereas increase on snout breadth imply in more vertical orbits. Size and encephalization quotients are uncorrelated with orbit orientation. Among ecological data, diet showed significant correlation whereas locomotion is the factor that less affects the position of orbits. Phylogeny is uncorrelated to any orbital parameters measured. Ecological factors seemingly play a more important role on orbit orientation than previously expected, and differentiation on orbit orientation seems to be more functional than inherited. Thus, despite the apparent homogeneity on didelphid morphology, there is subtle morphological variability that may be directly related to feeding behavior.
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Cranial sexual dimorphism in New World marsupials and a test of Rensch's rule in Didelphidae
Journal of Mammalogy, 2010Co-Authors: Diego AstúaAbstract:This study assessed the occurrence of sexual size dimorphism (SSD) and sexual shape dimorphism (SShD) in the skull and mandible of representatives of most species within the 3 orders of living New World opossums, Didelphimorphia, Paucituberculata, and Microbiotheria, using geometric morphometrics. Centroid sizes and partial warps were extracted from landmarks set on images of the dorsal, ventral, and lateral views of the skull and lateral view of the mandible, and were compared between sexes to estimate SSD and SShD. Specimens totaling 2,932 from 71 species of Didelphidae, 5 species of Caenolestidae, and 1 species of Microbiotheriidae were analyzed. SSD was variable in the Didelphimorphia and the Paucituberculata and absent in Microbiotheria. Similar results were found for SShD, but SSD and SShD are not clearly coupled. I also evaluated the validity of Rensch’s rule—the widely observed phenomenon of correlated increases in SSD and body size for male-biased sexual dimorphism, or correlated decreases in SSD in body size for female-biased sexual dimorphism—in the Didelphidae. Didelphids span 2 orders of magnitude in body size, and, when present, sexual dimorphism is male-biased. Regressions of SSD and SShD estimators onto size, using phylogenetic independent contrasts, showed either no significant relationship between SSD or SShD with size in any of the structures and views analyzed, or a trend contrary to Rensch’s rule (smaller species more dimorphic, but with male-biased dimorphism). Lack of adherence to Rensch’s rule in Didelphimorphia may relate to a lack of social interactions and male territoriality, usually associated with such a trend via sexual selection. If the trend contrary to Rensch’s rule is real, an explanation may lie in the increasing amount of smallbodied species that recently have been found to be semelparous and thus subject to stronger selection for larger males. DOI: 10.1644/09-MAMM-A-018.1.
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Evolution of scapula size and shape in didelphid marsupials (Didelphimorphia: Didelphidae).
Evolution; international journal of organic evolution, 2009Co-Authors: Diego AstúaAbstract:The New World family Didelphidae, the basal lineage within marsupials, is commonly viewed as morphologically conservative, yet includes aquatic, terrestrial, scansorial, and arboreal species. Here, I quantitatively estimated the existing variability in size and shape of the Didelphidae scapula (1076 specimens from 56 species) using geometric morphometrics, and compared size and shape differences to evolutionary and ecologic distances. I found considerable variation in the scapula morphology, most of it related to size differences between species. This results in morphologic divergence between different locomotor habits in larger species (resulting from increased mechanical loads), but most smaller species present similarly shaped scapulae. The only exceptions are the water opossum and the short-tailed opossums, and the functional explanations for these differences remain unclear. Scapula size and shape were mapped onto a molecular phylogeny for 32 selected taxa and ancestral size and shapes were reconstructed using squared-changed parsimony. Results indicate that the Didelphidae evolved from a medium- to small-sized ancestor with a generalized scapula, slightly more similar to arboreal ones, but strikingly different from big-bodied present arboreal species, suggesting that the ancestral Didelphidae was a small scansorial animal with no particular adaptations for arboreal or terrestrial habits, and these specializations evolved only in larger-bodied clades.
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Tooth Eruption Sequence and Replacement Pattern in Woolly Opossums, Genus Caluromys (Didelphimorphia: Didelphidae)
Journal of Mammalogy, 2008Co-Authors: Diego Astúa, Natália Oliveira LeinerAbstract:The sequence of molar eruption, along with the timing of replacement of the 3rd deciduous premolar by a permanent premolar, has been documented in several species in the family Didelphidae, and routinely used to establish age classes. We documented the dental eruption and replacement patterns in the 3 species of the neotropical marsupial genus Caluromys, which constitute one of the most basal groups within the Didelphidae. We examined 258 specimens of Caluromys derbianus, 54 specimens of C. lanatus, and 386 specimens of C. philander. These species have a dental eruption pattern that is similar to that of Marmosops, with replacement of the 3rd deciduous premolar after eruption of the 4th molar. However, we sometimes found incompletely erupted P3 and M4 occurring simultaneously as part of a M4–P3 eruption sequence. We suggest that the occurrence of this intermediate pattern in other taxa should be verified by examination of large series of specimens. Because teeth erupting in sequence can be erroneously considered as fitting an intermediate pattern, eruption sequence and time of completion of development should be used separately when using dental eruption in phylogenetic analyses. Because of the high degree of intraspecific variation observed in several taxa in Didelphidae, a system of age classes based solely on eruption of upper molars may be more useful than those that combine information on molar eruption sequence and timing of premolar replacement.
R. M. Lanfredi - One of the best experts on this subject based on the ideXlab platform.
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Further description of Cruzia tentaculata (Rudolphi, 1819) Travassos, 1917 (Nematoda: Cruzidae) by light and scanning electron microscopy
Parasitology research, 2009Co-Authors: F. A. O. Adnet, D. H. S. Anjos, A. Menezes-oliveira, R. M. LanfrediAbstract:Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.
F. A. O. Adnet - One of the best experts on this subject based on the ideXlab platform.
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Further description of Cruzia tentaculata (Rudolphi, 1819) Travassos, 1917 (Nematoda: Cruzidae) by light and scanning electron microscopy
Parasitology research, 2009Co-Authors: F. A. O. Adnet, D. H. S. Anjos, A. Menezes-oliveira, R. M. LanfrediAbstract:Species of Cruzia are parasites of the large intestine of marsupials, reptiles, amphibians, and mammalians. Cruzia tentaculata specimens were collected from the large intestine of Didelphis marsupialis (Mammalia: Didelphidae) from Colombia (new geographical record) and from Brazil and analyzed by light and scanning electron microscopy. The morphology of males and females by light microscopy corroborated most of the previous description and the ultrastructure by scanning electron microscopy evidence: the topography of the cuticle, deirids, amphids, phasmids in both sexes, a pair of papillae near the vulva opening, and the number and location of male caudal papillae, adding new features for species identification only observed by this technique.
Maria Nazareth F. Da Silva - One of the best experts on this subject based on the ideXlab platform.
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Variations of chromosomal structures in Caluromys philander (Didelphimorphia: Didelphidae) from the Amazon region
Genetica, 2013Co-Authors: Érica Martinha Silva Souza, Maria Nazareth F. Da Silva, Carlos Eduardo Faresin E Silva, Eduardo Schmidt Eler, Eliana FeldbergAbstract:Caluromys is considered to be one of the most ancient genera of extant marsupials and is positioned among the basal taxa of the family Didelphidae. At least two species occur in Brazil, C. philander and C. lanatus , both of which have 2n = 14 chromosomes. For the first time, we present evidence of an intrapopulation polymorphism of the sexual chromosome pair in C. philander females from the Central Amazon region. Detailed cytogenetic results of animals from three localities on the Amazon region were analyzed using classical cytogenetics (NOR, C-Band and G-Band) and molecular techniques (18S rDNA and telomere probes). Similar to other conspecific individuals, the diploid number of these animals is 2n = 14, and their fundamental number is 24, with NOR present on the 6th autosomal pair. The X chromosome presented variation detectable by G banding, suggesting a pericentric inversion.
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Gracilinanus microtarsus (Didelphimorphia: Didelphidae)
Mammalian Species, 2010Co-Authors: Mathias M. Pires, Maria Nazareth F. Da Silva, Eduardo G. Martins, Sérgio F. Dos ReisAbstract:Gracilinanus microtarsus (J. A. Wagner, 1842), called the Brazilian gracile opossum, is a small didelphid that is 1 of 6 species in the genus Gracilinanus. It is a sexually dimorphic, solitary marsupial that has a highly seasonal reproductive pattern. It inhabits Atlantic rain forests and semideciduous forests interspersed in the highly seasonal cerrado (savanna-like vegetation) in southeastern and southern Brazil. It prefers locations associated with low canopy cover and it also occurs in habitats altered by anthropogenic events. The species is classified as Least Concern by the International Union for Conservation of Nature and Natural Resources.
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Relationships among didelphid marsupials based on sequence variation in the mitochondrial cytochrome B gene
Journal of Mammalian Evolution, 1996Co-Authors: James L. Patton, Sergio F. Reis, Maria Nazareth F. Da SilvaAbstract:Variation in the mitochondrial cytochrome b gene (nucleotide and amino acid sequences) is evaluated for 9 genera and 15 species of American opossums in the family Didelphidae, using the American caenolestid rat opossum Lestoros and the New Guinean peroryctid bandicoot Echimypera as outgroups. Phylogenetic analyses (parsimony and distance) strongly support the monophyly of the Didelphidae and delineate two major clades; (1) Didelphis and Philander are strongly aligned sister taxa, with Metachirus weakly but consistently associated with them, and (2) Marmosa plus Micoureus , with Monodelphis falling outside that pair. The genera Marmosops, Caluromys , and Glironia exhibit varied relationships, depending upon the method of analysis and data (DNA or amino acid sequences) used, but generally are placed individually or in combinations near or at the base of the didelphid radiation. Some aspects of these relationships are consistent with current taxonomic views, but others are in marked contrast. Specifically, a clade comprised of the mouse opossums Marmosa, Micoureus , and Marmosops is strongly rejected by log-likelihood analysis, contrary to expectations from some current classifications. Also, the woolly opossums Caluromys and Glironia also do not form a sister-taxon relationship, as suggested by their placement in a subfamily separate from the remaining didelphids examined. However, such a relationship cannot be rejected from log-likelihood analyses. The relationships suggested from cyt-b sequences are strongly concordant with those based on DNA-DNA hybridization analyses. In addition to systematic and phylogenetic properties, molecular evolution of the didelphid cytochrome b gene sequence is characterized according to nucleotide bias and rate differentials at each codon position and across the entire sequence.
Margarete S. Mattevi - One of the best experts on this subject based on the ideXlab platform.
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Phylogeny of Thylamys (Didelphimorphia, Didelphidae) species... Phylogeny of Thylamys (Didelphimorphia, Didelphidae) species,
2016Co-Authors: Bianca De A. Carvalho, Luiz F. B. Oliveira, Margarete S. MatteviAbstract:ABSTRACT. The genus Thylamys Gray, 1843 lives in the central and southern portions of South America inhabiting open and shrub-like vegetation, from prairies to dry forest habitats in contrast to the preference of other Didelphidae genera for more mesic environments
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Phylogenetic relationships and phylogeographic patterns in Monodelphis (Didelphimorphia: Didelphidae)
Journal of Mammalogy, 2011Co-Authors: Bianca De A. Carvalho, Luiz Flamarion B. Oliveira, Alfredo Langguth, Cristina Claumann Freygang, Renato S. Ferraz, Margarete S. MatteviAbstract:Monodelphis (short-tailed opossums) is the most speciose South American marsupial genus, wtih species distributed from Panama to Argentina. The goal of the present study was to analyze levels and patterns of genetic variation in M. brevicaudata (Guianan short-tailed opossum), M. dimidiata (yellow-sided opossum), M. domestica (gray short-tailed opossum), and M. kunsi (pygmy short-tailed opossum) using sequences of the mitochondrial cytochrome b (Cytb) and nuclear interphotoreceptor retinoid-binding protein (IRBP) genes from individuals sampled in the Amazon, Cerrado, Caatinga, Atlantic Forest, and Pampa biomes in Brazil. Species relationships also were analyzed using sequences of 9 other Monodelphis species retrieved from GenBank and representing 3 localities in Brazil and 17 sites in other South American countries. M. domestica and M. brevicaudata showed phylogeographic structure, but M. dimidiata and M. kunsi did not. Maximum parsimony, maximum likelihood, and Bayesian algorithms showed similar topologies for estimated phylogenetic trees. Analyses of individual genes produced comparable results, but combined loci produced trees with higher support. All Monodelphis haplotypes were monophyletic, with M. emiliae (Emilia's short-tailed opossum) sister to all other species, which form 2 groups. M. brevicaudata (from the Amazon) forms a well-supported clade with M. domestica (which occupies several biomes) and 2 unidentified Amazonian species. The other branch has M. kunsi (from the Cerrado) as sister to a well-supported clade of 5 Amazonian species.
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KARYOTYPES OF NINETEEN MARSUPIAL SPECIES FROM BRAZIL
Journal of Mammalogy, 2002Co-Authors: Bianca De Almeida Carvalho, Luiz Flamarion B. Oliveira, Andrea P. Nunes, Margarete S. MatteviAbstract:Karyotypes of 127 individuals, representing 19 species of 10 genera of Brazilian marsupials (Didelphidae) were determined, with karyotypes of Gracilinanus emiliae and G. microtarsus, Marmosops incanus, Thylamys velutinus, and Philander frenata being described for the 1st time. The specimens were collected from 24 localities, in an area between 4°N (Surumu, Roraima) and 31°S (Mostardas, Rio Grande do Sul), in Brazil. Only 3 diploid numbers were found, 2n = 14 in G. emiliae, G. microtarsus, G. agilis, Marmosa murina, Marmosops parvidens, M. incanus, Micoureus demerarae, and T. velutinus; 2n = 18 in Monodelphis dimidiata, M. brevicaudata, M. kunsi, and M. domestica; and 2n = 22 in Chironectes minimus, Lutreolina crassicaudata, Didelphis albiventris, D. aurita, D. marsupialis, Philander opossum, and P. frenata.