Horacio Schneider | UFPA - Federal University of Pará (original) (raw)

Papers by Horacio Schneider

Research paper thumbnail of Hybridization and massive mtDNA unidirectional introgression between the closely related Neotropical toads Rhinella marina and R. schneideri inferred from mtDNA and nuclear markers

Background The classical perspective that interspecific hybridization in animals is rare has been... more Background The classical perspective that interspecific hybridization in animals is rare has been changing due to a growing list of empirical examples showing the occurrence of gene flow between closely related species. Using sequence data from cyt b mitochondrial gene and three intron nuclear genes (RPL9, c-myc, and RPL3) we investigated patterns of nucleotide polymorphism and divergence between two closely related toad species R. marina and R. schneideri.

Research paper thumbnail of Molecular studies of Callithrix pygmaea (Primates, Platyrrhini) based on transferrin intronic and ND1 regions: Implications for taxonomy and conservation

Traditional classifications of Platyrrhini monkeys, based mainly on morphological features, are b... more Traditional classifications of Platyrrhini monkeys, based mainly on morphological features, are being contested by recent molecular data. The subfamily Callitrichinae (Platyrrhini, Primates) consists of a diverse group of species, many of them considered endangered. Our analysis of two DNA regions, a mtDNA gene (ND1) and a nuclear gene (intronic regions of the transferrin gene), suggests that Callithrix pygmaea may have sufficient variability to justify the existence of subspecies or even separate species.

Research paper thumbnail of The prion protein and New World primate phylogeny

ABSTRACT The PrP C prion protein contains 250 amino acids with some variation among species and i... more ABSTRACT The PrP C prion protein contains 250 amino acids with some variation among species and is expressed in several cell types. PrP C is converted to PrP Sc by a post-translational process in which it acquires amino acid sequences of three-dimensional conformation of b-sheets. Variations in the prion protein gene were observed among 16 genera of New World primates (Platyrrhini), and resulted in amino acid substitutions when compared with the human sequence.

Research paper thumbnail of Population genetic structuring of the king weakfish, Macrodon ancylodon (Sciaenidae), in Atlantic coastal waters of South America: deep genetic divergence without morphological change

Abstract Phylogeographic patterns in Macrodon ancylodon sampled from 12 locations across all its ... more Abstract Phylogeographic patterns in Macrodon ancylodon sampled from 12 locations across all its range were investigated using mitochondrial DNA cytochrome b sequences, and analysed together with patterns of morphometric differentiation. Populations of the North Brazil and the Brazil currents, with warmer waters, form a clade (tropical clade) separated by 23 fixed mutations from the populations that inhabit regions of colder waters influenced by the Brazil and Malvinas currents (subtropical clade).

Research paper thumbnail of Identification and phylogenetic inferences on stocks of sharks affected by the fishing industry off the Northern coast of Brazil

Abstract The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontr... more Abstract The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate.

Research paper thumbnail of Molecular phylogeny of mangrove oysters (Crassostrea) from Brazil

ABSTRACT As a result of phenotypic plasticity, the cupped oysters (Crassostrea) are difficult to ... more ABSTRACT As a result of phenotypic plasticity, the cupped oysters (Crassostrea) are difficult to identify by means of their morphology. However, molecular DNA markers are a useful means of discriminating among these species. Cupped oysters are one of the most widely cultured marine invertebrates and correct species identification is important in aquaculture. Moreover, the molecular phylogeny of the genus Crassostrea and the subfamily Crassostreinae is still not clear.

Research paper thumbnail of Polymorphism of phosphogluconate dehydrogenase (PGD) in New World monkeys: taxonomic significance

ABSTRACT Phosphogluconate dehydrogenase (PGD) polymorphism in 23 species of 13 genera of New Worl... more ABSTRACT Phosphogluconate dehydrogenase (PGD) polymorphism in 23 species of 13 genera of New World monkeys was investigated. The occurrence of 21 codominant autosome alleles may explain the total electrophoretic variation encountered. The only alleles shared by two or more genera were PGD* 11 and PGD* 15, the former grouping Aotus, Cacajao, Chiropotes, Saimirí, Cebuella, Callithrix and Sagidnus, and the latter Alouatta, Lagothrix,

Research paper thumbnail of Molecular phylogeny of the genus Saguinus (Platyrrhini, Primates) based on the ND1 mitochondrial gene and implications for conservation

The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys... more The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys from South America and Panama, remains an area of considerable discussion despite many investigations, there being continuing controversy over subgeneric taxonomic classifications based on morphological characters.

Research paper thumbnail of Population Structure of Lutjanus purpureus (Lutjanidae-Perciformes) on the Brazilian coast: further existence evidence of a single species of red snapper in the western Atlantic

ABSTRACT The present study focus on the mitochondrial control region to investigate phylogeograph... more ABSTRACT The present study focus on the mitochondrial control region to investigate phylogeographic patterns and population structure in Lutjanus purpureus, and to evaluate the genetic similarity between L. purpureus and L. campechanus. For the initial analysis, 810 base pairs sequence from control region were obtained from 239 specimens of L. purpureus collected from four localities off the Brazilian coast.

Research paper thumbnail of Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia) specimens

The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now n... more The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested.

Research paper thumbnail of Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters

Abstract We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths... more Abstract We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths and anteaters) and used these sequences along with GenBank sequences of both extant and extinct sloths to perform phylogenetic analysis based on parsimony, maximum-likelihood and Bayesian methods. By increasing the taxa density for anteaters and sloths we were able to clarify some points of the Pilosa phylogenetic tree.

Research paper thumbnail of Molecular identification, phylogeny and geographic distribution of Brazilian mangrove oysters (Crassostrea)

Abstract Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology ... more Abstract Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology is of limited value for species identification and taxonomy. By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Brazilian coast, and phylogenetically relate these to other Crassostrea from different parts of the world. Sequencing of the partial cytochrome oxidase c subunit I gene (COI), revealed a total of three species of Crassostrea at 16 locations along the Brazilian coast. C.

Research paper thumbnail of Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)

A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree ... more A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree was enriched with the area of occurrence and with information on the karyotype of the samples. Based on this enriched tree, and with a described methodology, hypotheses were proposed on the karyotype and area of occurrence of the ancestors of each Clade.

Research paper thumbnail of The history of the introduction of the giant river prawn, Macrobrachium cf. rosenbergii (Decapoda, Palaemonidae), in Brazil: new insights from molecular data

Abstract The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated fres... more Abstract The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated freshwater prawns in the world and has been introduced into more than 40 countries. In some countries, this prawn is considered an invasive species that requires close monitoring. Recent changes in the taxonomy of this species (separation of M. rosenbergii and M. dacqueti) require a re-evaluation of introduced taxa.

Research paper thumbnail of Phylogenetic relationships among Brazilian howler monkeys, genus Alouatta (Platyrrhini, Atelidae), based on g1-globin pseudogene sequences

The genus Alouatta (howler monkeys) is the most widely distributed of New World primates, and has... more The genus Alouatta (howler monkeys) is the most widely distributed of New World primates, and has been arranged in three species groups: the Central American Alouatta palliata group and the South American Alouatta seniculus and Alouatta caraya groups. While the latter is monotypic, the A. seniculus group encompasses at least three species (A. seniculus, A. belzebul and A. fusca). In the present study, approximately 600 base pairs of the g1-globin pseudogene were sequenced in the four Brazilian species (A.

Research paper thumbnail of Genetic characterization of native and introduced populations of the neotropical cichlid genus Cichla in Brazil

Abstract A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control R... more Abstract A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control Region sequences from native and introduced populations was undertaken, in order to characterize the introduction of Cichla (peacock bass or tucunaré) species in Brazil. Mitochondrial DNA haplotypes found in introduced fish from Minas Gerais state (southeastern Brazil) clustered only with those from native species of the Tocantins River (Cichla piquiti and C.

Research paper thumbnail of CHROMOSOME AND PROTEIN VARIATION IN RED HOWLER MONKEYS

ABSTRACT Electrophoretic and karyotypic data were obtained for 16 specimens of Alouatta seniculus... more ABSTRACT Electrophoretic and karyotypic data were obtained for 16 specimens of Alouatta seniculus collected at the east margin of the Jari River, in Brazilian Amazonia. Diploid numbers of 47, 48 and 49 chromosomes were observed, this variation being due to the presence of 1 to 3 supernumerary microchromosomes. These and other karyotypic characteristics are at variance with results for this same species obtained in Colombia and Bolivia. Genetic variability in A.

Research paper thumbnail of Análise filogenética de duas espécies simpátricas de tucunaré (Cichla, Perciformes), com registro de hibridização em diferentes pontos da bacia amazônica

ABSTRACT Among the species of Amazonian fishes of recognized economic importance, we may highligh... more ABSTRACT Among the species of Amazonian fishes of recognized economic importance, we may highlight Cichla (tucunarés) species, which is the biggest cichlid from South America. This genus is described as having at least 15 different forms, but recent authors accept only five valid species: Cichla temensis, C. monoculus, C. orinocensis, C. ocellaris and C. intermedia. Recent chromosomal analysis in tucunarés from the Balbina reservoir suggested a possible hybridization between Cichla monoculus and C.

Research paper thumbnail of Novel 12S mtDNA findings in sloths (Pilosa, Folivora) and anteaters (Pilosa, Vermilingua) suggest a true case of long branch attraction

Abstract We sequenced 12S RNA mtDNA for the majority of the extant species of sloths and anteater... more Abstract We sequenced 12S RNA mtDNA for the majority of the extant species of sloths and anteaters and compared our results with previous data obtained by our group using 16S RNA mtDNA in the same specimens and to GenBank sequences of the extinct giant sloth Mylodon.

Research paper thumbnail of Population Genetic Studies of Mitochondrial Pseudo-Control Region in the Endangered Araripe Manakin (Antilophia bokermanni)

Abstract The Araripe Manakin (Passeriformes: Pipridae: Antilophia bokermanni) is the most threate... more Abstract The Araripe Manakin (Passeriformes: Pipridae: Antilophia bokermanni) is the most threatened passeriform species and is classified as critically endangered. With an estimated population of only 800 individuals, this species is endemic to a small area (-30 km2) of forest on the slopes of the Araripe Plateau in northeastern Brazil. The urgent need to implement an effective conservation program for the Araripe Manakin has stimulated intensive research into various aspects of its biology.

Research paper thumbnail of Hybridization and massive mtDNA unidirectional introgression between the closely related Neotropical toads Rhinella marina and R. schneideri inferred from mtDNA and nuclear markers

Background The classical perspective that interspecific hybridization in animals is rare has been... more Background The classical perspective that interspecific hybridization in animals is rare has been changing due to a growing list of empirical examples showing the occurrence of gene flow between closely related species. Using sequence data from cyt b mitochondrial gene and three intron nuclear genes (RPL9, c-myc, and RPL3) we investigated patterns of nucleotide polymorphism and divergence between two closely related toad species R. marina and R. schneideri.

Research paper thumbnail of Molecular studies of Callithrix pygmaea (Primates, Platyrrhini) based on transferrin intronic and ND1 regions: Implications for taxonomy and conservation

Traditional classifications of Platyrrhini monkeys, based mainly on morphological features, are b... more Traditional classifications of Platyrrhini monkeys, based mainly on morphological features, are being contested by recent molecular data. The subfamily Callitrichinae (Platyrrhini, Primates) consists of a diverse group of species, many of them considered endangered. Our analysis of two DNA regions, a mtDNA gene (ND1) and a nuclear gene (intronic regions of the transferrin gene), suggests that Callithrix pygmaea may have sufficient variability to justify the existence of subspecies or even separate species.

Research paper thumbnail of The prion protein and New World primate phylogeny

ABSTRACT The PrP C prion protein contains 250 amino acids with some variation among species and i... more ABSTRACT The PrP C prion protein contains 250 amino acids with some variation among species and is expressed in several cell types. PrP C is converted to PrP Sc by a post-translational process in which it acquires amino acid sequences of three-dimensional conformation of b-sheets. Variations in the prion protein gene were observed among 16 genera of New World primates (Platyrrhini), and resulted in amino acid substitutions when compared with the human sequence.

Research paper thumbnail of Population genetic structuring of the king weakfish, Macrodon ancylodon (Sciaenidae), in Atlantic coastal waters of South America: deep genetic divergence without morphological change

Abstract Phylogeographic patterns in Macrodon ancylodon sampled from 12 locations across all its ... more Abstract Phylogeographic patterns in Macrodon ancylodon sampled from 12 locations across all its range were investigated using mitochondrial DNA cytochrome b sequences, and analysed together with patterns of morphometric differentiation. Populations of the North Brazil and the Brazil currents, with warmer waters, form a clade (tropical clade) separated by 23 fixed mutations from the populations that inhabit regions of colder waters influenced by the Brazil and Malvinas currents (subtropical clade).

Research paper thumbnail of Identification and phylogenetic inferences on stocks of sharks affected by the fishing industry off the Northern coast of Brazil

Abstract The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontr... more Abstract The ongoing decline in abundance and diversity of shark stocks, primarily due to uncontrolled fishery exploitation, is a worldwide problem. An additional problem for the development of conservation and management programmes is the identification of species diversity within a given area, given the morphological similarities among shark species, and the typical disembarkation of processed carcasses which are almost impossible to differentiate.

Research paper thumbnail of Molecular phylogeny of mangrove oysters (Crassostrea) from Brazil

ABSTRACT As a result of phenotypic plasticity, the cupped oysters (Crassostrea) are difficult to ... more ABSTRACT As a result of phenotypic plasticity, the cupped oysters (Crassostrea) are difficult to identify by means of their morphology. However, molecular DNA markers are a useful means of discriminating among these species. Cupped oysters are one of the most widely cultured marine invertebrates and correct species identification is important in aquaculture. Moreover, the molecular phylogeny of the genus Crassostrea and the subfamily Crassostreinae is still not clear.

Research paper thumbnail of Polymorphism of phosphogluconate dehydrogenase (PGD) in New World monkeys: taxonomic significance

ABSTRACT Phosphogluconate dehydrogenase (PGD) polymorphism in 23 species of 13 genera of New Worl... more ABSTRACT Phosphogluconate dehydrogenase (PGD) polymorphism in 23 species of 13 genera of New World monkeys was investigated. The occurrence of 21 codominant autosome alleles may explain the total electrophoretic variation encountered. The only alleles shared by two or more genera were PGD* 11 and PGD* 15, the former grouping Aotus, Cacajao, Chiropotes, Saimirí, Cebuella, Callithrix and Sagidnus, and the latter Alouatta, Lagothrix,

Research paper thumbnail of Molecular phylogeny of the genus Saguinus (Platyrrhini, Primates) based on the ND1 mitochondrial gene and implications for conservation

The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys... more The systematics of the subfamily Callitrichinae (Platyrrhini, Primates), a group of small monkeys from South America and Panama, remains an area of considerable discussion despite many investigations, there being continuing controversy over subgeneric taxonomic classifications based on morphological characters.

Research paper thumbnail of Population Structure of Lutjanus purpureus (Lutjanidae-Perciformes) on the Brazilian coast: further existence evidence of a single species of red snapper in the western Atlantic

ABSTRACT The present study focus on the mitochondrial control region to investigate phylogeograph... more ABSTRACT The present study focus on the mitochondrial control region to investigate phylogeographic patterns and population structure in Lutjanus purpureus, and to evaluate the genetic similarity between L. purpureus and L. campechanus. For the initial analysis, 810 base pairs sequence from control region were obtained from 239 specimens of L. purpureus collected from four localities off the Brazilian coast.

Research paper thumbnail of Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia) specimens

The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now n... more The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested.

Research paper thumbnail of Phylogenetic analysis of 16S mitochondrial DNA data in sloths and anteaters

Abstract We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths... more Abstract We sequenced part of the 16S rRNA mitochondrial gene in 17 extant taxa of Pilosa (sloths and anteaters) and used these sequences along with GenBank sequences of both extant and extinct sloths to perform phylogenetic analysis based on parsimony, maximum-likelihood and Bayesian methods. By increasing the taxa density for anteaters and sloths we were able to clarify some points of the Pilosa phylogenetic tree.

Research paper thumbnail of Molecular identification, phylogeny and geographic distribution of Brazilian mangrove oysters (Crassostrea)

Abstract Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology ... more Abstract Oysters (Ostreidae) manifest a high degree of phenotypic plasticity, whereby morphology is of limited value for species identification and taxonomy. By using molecular data, the aim was to genetically characterize the species of Crassostrea occurring along the Brazilian coast, and phylogenetically relate these to other Crassostrea from different parts of the world. Sequencing of the partial cytochrome oxidase c subunit I gene (COI), revealed a total of three species of Crassostrea at 16 locations along the Brazilian coast. C.

Research paper thumbnail of Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)

A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree ... more A new molecular phylogeny for akodontine rodents from Brazil was proposed. The phylogenetic tree was enriched with the area of occurrence and with information on the karyotype of the samples. Based on this enriched tree, and with a described methodology, hypotheses were proposed on the karyotype and area of occurrence of the ancestors of each Clade.

Research paper thumbnail of The history of the introduction of the giant river prawn, Macrobrachium cf. rosenbergii (Decapoda, Palaemonidae), in Brazil: new insights from molecular data

Abstract The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated fres... more Abstract The giant river prawn, Macrobrachium cf. rosenbergii, is one of the most cultivated freshwater prawns in the world and has been introduced into more than 40 countries. In some countries, this prawn is considered an invasive species that requires close monitoring. Recent changes in the taxonomy of this species (separation of M. rosenbergii and M. dacqueti) require a re-evaluation of introduced taxa.

Research paper thumbnail of Phylogenetic relationships among Brazilian howler monkeys, genus Alouatta (Platyrrhini, Atelidae), based on g1-globin pseudogene sequences

The genus Alouatta (howler monkeys) is the most widely distributed of New World primates, and has... more The genus Alouatta (howler monkeys) is the most widely distributed of New World primates, and has been arranged in three species groups: the Central American Alouatta palliata group and the South American Alouatta seniculus and Alouatta caraya groups. While the latter is monotypic, the A. seniculus group encompasses at least three species (A. seniculus, A. belzebul and A. fusca). In the present study, approximately 600 base pairs of the g1-globin pseudogene were sequenced in the four Brazilian species (A.

Research paper thumbnail of Genetic characterization of native and introduced populations of the neotropical cichlid genus Cichla in Brazil

Abstract A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control R... more Abstract A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control Region sequences from native and introduced populations was undertaken, in order to characterize the introduction of Cichla (peacock bass or tucunaré) species in Brazil. Mitochondrial DNA haplotypes found in introduced fish from Minas Gerais state (southeastern Brazil) clustered only with those from native species of the Tocantins River (Cichla piquiti and C.

Research paper thumbnail of CHROMOSOME AND PROTEIN VARIATION IN RED HOWLER MONKEYS

ABSTRACT Electrophoretic and karyotypic data were obtained for 16 specimens of Alouatta seniculus... more ABSTRACT Electrophoretic and karyotypic data were obtained for 16 specimens of Alouatta seniculus collected at the east margin of the Jari River, in Brazilian Amazonia. Diploid numbers of 47, 48 and 49 chromosomes were observed, this variation being due to the presence of 1 to 3 supernumerary microchromosomes. These and other karyotypic characteristics are at variance with results for this same species obtained in Colombia and Bolivia. Genetic variability in A.

Research paper thumbnail of Análise filogenética de duas espécies simpátricas de tucunaré (Cichla, Perciformes), com registro de hibridização em diferentes pontos da bacia amazônica

ABSTRACT Among the species of Amazonian fishes of recognized economic importance, we may highligh... more ABSTRACT Among the species of Amazonian fishes of recognized economic importance, we may highlight Cichla (tucunarés) species, which is the biggest cichlid from South America. This genus is described as having at least 15 different forms, but recent authors accept only five valid species: Cichla temensis, C. monoculus, C. orinocensis, C. ocellaris and C. intermedia. Recent chromosomal analysis in tucunarés from the Balbina reservoir suggested a possible hybridization between Cichla monoculus and C.

Research paper thumbnail of Novel 12S mtDNA findings in sloths (Pilosa, Folivora) and anteaters (Pilosa, Vermilingua) suggest a true case of long branch attraction

Abstract We sequenced 12S RNA mtDNA for the majority of the extant species of sloths and anteater... more Abstract We sequenced 12S RNA mtDNA for the majority of the extant species of sloths and anteaters and compared our results with previous data obtained by our group using 16S RNA mtDNA in the same specimens and to GenBank sequences of the extinct giant sloth Mylodon.

Research paper thumbnail of Population Genetic Studies of Mitochondrial Pseudo-Control Region in the Endangered Araripe Manakin (Antilophia bokermanni)

Abstract The Araripe Manakin (Passeriformes: Pipridae: Antilophia bokermanni) is the most threate... more Abstract The Araripe Manakin (Passeriformes: Pipridae: Antilophia bokermanni) is the most threatened passeriform species and is classified as critically endangered. With an estimated population of only 800 individuals, this species is endemic to a small area (-30 km2) of forest on the slopes of the Araripe Plateau in northeastern Brazil. The urgent need to implement an effective conservation program for the Araripe Manakin has stimulated intensive research into various aspects of its biology.