title: Chromosomal polymorphism in Rineloricaria lanceolata Günther, 1868 (Loricariidae: Loricariinae) of the Paraguay basin (Mato Grosso do Sul, Brazil): evidence of fusions and their consequences in the population.
abstract: Rineloricaria is the most species-rich genus of the Loricariinae (armored catfish) with 65 valid species. However, the karyotype structure is known only for eight species in this group. This study provides cytogenetic data for Rineloricaria lanceolata collected from the upper Paraguay basin (Mato Grosso do Sul). The specimens revealed extensive chromosomal polymorphism constituting 10 karyotypes, which differed in the diploid number (48 to 45 chromosomes) and fundamental number (FN) between 52 and 55. Three types of chromosome variants were observed: a medium-sized submetacentric, a large submetacentric, and a small acrocentric form. Internal telomere sequences were demonstrated by a telomeric (TTAGGG)n probe in submetacentric chromosome variants, suggesting Robertsonian and tandem fusions. Considering the karyotype 2n=48 (4m+2st+42a, FN=54) as the starting point for this polymorphism, these rearrangements contributed to the reduction in diploid number (48-45). Furthermore, a remarkable polymorphism of 18S rDNA resulted in three nucleolus organizer region phenotypes (I, II, and III) with variable frequencies. Interestingly, this polymorphism has remained in the population through interbreeding between specimens, resulting in different viable combinations. The data obtained confirm that diversification/karyotype evolution in Rineloricaria was marked by numerous chromosomal rearrangements which appear to be well tolerated in the panmitic population.
authors: 1 Departamento de Biotecnologia, Genética e Biologia Celular, Universidade Estadual de Maringá , Maringá, Brazil .
authors: Fernanda Errero
authors: FE
authors: Porto
authors: Margarida Maria de Rossi
authors: MM
authors: Vieira
authors: Ligia Magrinelli
authors: LM
authors: Barbosa
authors: Luciana Andréia
authors: LA
authors: Borin-Carvalho
authors: Marcelo Ricardo
authors: MR
authors: Vicari
authors: Ana Luiza de Brito
authors: AL
authors: Portela-Castro
authors: Isabel Cristina
authors: IC
authors: Martins-Santos
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001938:Brazil; D002397:Catfishes / Q000235:genetics*; D002875:Chromosomes / Q000648:ultrastructure*; D020732:Cytogenetic Analysis; D005260:Female; D007621:Karyotyping; D008297:Male; D008856:Microscopy, Fluorescence; D011110:Polymorphism, Genetic