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Farlowella is the second richest genus in Loricariinae, broadly distributed in freshwater streams and rivers of South America. In this article, we aimed to expand on the cytogenetic and molecular data available for two allopatric populations of Farlowella hahni. Both populations had diploid chromosome number 58, but with karyotype differences, indicative of chromosomal rearrangements. C-banding showed large heterochromatic blocks at telomeric regions in acrocentric chromosomes in both populations. Fluorescence in situ hybridization (FISH) revealed a single 18S rDNA site in both populations and a single 5S rDNA site for individuals from lower Parana River basin (native region) and multiple 5S rDNA sites for individuals from upper Parana River basin (non-native region). Mitochondrial sequence analyses did not separate the two F. hahni populations. The cytogenetic and molecular data obtained are relevant in a preliminary study and suggested the existence of cryptic diversity and the hypothesis that at least two Farlowella lineages may coexist in the Parana basin.

Made available in DSpace on 2019-10-06T15:32:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-01 Astyanax is a genus with a wide distribution ranging from the south United States to north of Patagonia (Argentina). The available cytogenetic data on Astyanax indicate a high karyotypic diversity, with diploid number of 36-52 chromosomes, presence of B chromosomes, heterochromatin polymorphism, and variations with respect to the number and localization of nucleolar organizer regions (NORs) and 18S and 5S ribosomal DNA sites. In the present study, we estimated the evolutionary history and times of divergence for 10 nominal Astyanax species from the South and Central/North American (Cna) continents, which present distinct chromosomal characteristics, based on molecular clocks inferred from mitochondrial DNA sequence. The molecular clock results indicate the origin of three distinct clades (Humeral dark spot [Hds]; Diffuse humeral spot [Dhs]; Cna group) during the late Miocene about 11.2 million years ago (Mya). Thus, Astyanax mexicanus (Cna) represent a species that diverged a long time ago (∼8.6 Mya) from the Hds group, and Astyanax schubarti is the oldest species (∼6.5 Mya) among the Dhs species. Laboratório de Citogenética Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista júlio de Mesquita Filho (UNESP), Avenue 24A Universidade Estadual de Mato Grosso Do sul (UEMS) Unidade de Mundo Novo Universidade Federal Do Rio de Janeiro (UFRJ) Núcleo em Ecologia e Desenvolvimento Socioambiental de Macaé (NUPEM/UFRJ) Laboratório de Genética Animal Departamento de Biologia e Zoologia Instituto de Biociências Universidade Federal de Mato Grosso (UFMT) Laboratório de Citogenética Departamento de Biologia Instituto de Biociências Universidade Estadual Paulista júlio de Mesquita Filho (UNESP), Avenue 24A

Made available in DSpace on 2018-12-11T16:47:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2016-01-01 Repetitive sequences and their chromosomal locations have been widely studied in species of the Astyanax genus. However, the chromosomal organization of U2 snDNA remains largely unknown. The aims of this study were to examine the chromosomal contexts of U2 snRNA and 5S rRNA genes in Astyanax species and determine the degree of chromosome morphological similarity between species with different diploid numbers. Clusters of U2 snDNA and 5S rDNA were determined in nine species of Astyanax, including two karyomorphs of Astyanax fasciatus Cuvier, 1819. All species exhibited U2 snDNA clusters on two chromosome pairs, except Astyanax mexicanus De Filippi, 1853 (one pair). The 5S rDNA clusters were located on one chromosome pair in Astyanax altiparanae Garutti and Britski, 2000, and Astyanax marionae Eigenmann, 1911, two pairs in Astyanax abramis Jenyns, 1842, Astyanax asuncionensis Géry, 1972, Astyanax bockmanni Vari and Castro, 2007, Astyanax eigenmanniorum Cope, 1894, A. fasciatus (karyomorphs I and II), and Astyanax schubarti Britski, 1964, and four pairs in A. mexicanus. The relationships between the repetitive sequences in different species suggest that A. schubarti and A. mexicanus exhibit an unusual U2 snDNA chromosomal format as a result of events occurring in the evolutionary history of the Astyanax group. Laboratório de Citogenética Departamento de Biologia Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515 Laboratório de Genética Animal Departamento de Biologia e Zoologia, Universidade Federal de Mato Grosso (UFMT) Laboratório de Citogenética Departamento de Biologia Universidade Estadual Paulista Júlio de Mesquita Filho (UNESP), Av. 24A, 1515

Made available in DSpace on 2015-10-21T13:12:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The species of genus Astyanax is widely distributed in freshwater neotropical zones. Astyanax is considered to be taxonomically confused, similar to other genera placed incertae sedis in Characidae. The cytogenetics of this genus is well characterized; species vary widely in diploid number, from 2n=36 chromosomes in Astyanax schubarti to 2n=50 for most species studied. The size, number, and position of different cytological markers vary among species and populations of Astyanax. We analyzed the karyotypes of individuals from three Astyanax species (Astyanax abramis, Astyanax altiparanae, and Astyanax eigenmanniorum) from populations not previously analyzed. We describe variations in several cytogenetic markers and the karyotypic relationships between them, specifically focusing on the characteristics of the conserved and divergent locations of the ribosomal genes. Our data are useful for establishing relationships between species and for investigating the karyotype evolution within the genus. Universidade Estadual Paulista ‘‘Júlio de Mesquita Filho’’ (UNESP) - Laboratório de Citogenética, Departamento de Biologia, Instituto de Biociências, Rio Claro, São Paulo, Brasil. Empresa Brasileira de Pesquisa Agropecuária (Embrapa) Pesca e Aquicultura (CNPASA), Palmas, Tocantins, Brasil Universidade Estadual Paulista ‘‘Júlio de Mesquita Filho’’ (UNESP) - Laboratório de Citogenética, Departamento de Biologia, Instituto de Biociências, Rio Claro, São Paulo, Brasil.