Allozyme analysis of the four species of Hypostomus (Teleostei: Loricariidae) from the Ivaí river, upper Paraná river basin, Brazil / Análise aloenzimática de quatro espécies de Hypostomus (Teleostei: Loricariidae) do rio Ivaí, bacia do alto rio Paraná, Brasil

Allozyme electrophoresis analysis were performed in four species of Hypostomus (Loricariidae), H. albopunctatus, H. hermanni, H. regani, and Hypostomus sp. 1/NUP 5612 from the Ivaí river, a tributary of the upper Paraná river. The study of 14 loci revealed diagnostic characters and exclusive alleles in a low frequency. The heterozygosity ranged from 0.000 in H. albopunctatus to 0.199 in H. hermanni, which was higher than the heterozygosity in other samples of Hypostomus in literature, as well as in other fish groups. Hypostomus albopunctatus and H. regani revealed higher similarity (I = 0.804), while H. hermanni and Hypostomus sp. 1/NUP 5612 showed the least genetic identity (I = 0.569). All samples were genetically distinguished, despite there were several shared alleles. The FST value was 0.671, showing a high genetic differentiation among the samples. Hypostomus sp. 1/NUP 5612 was genetically distinguished from the three congeners by the loci Adh-A and G3pdh-B and by present rare exclusive alleles in other six enzymatic systems.

Análises aloenzimáticas foram realizadas em quatro espécies de Hypostomus (Loricariidae), H. albopunctatus, H. hermanni, H. regani e Hypostomus sp. 1/NUP 5612 coletadas no rio Ivaí, um tributário da bacia do alto rio Paraná, através da técnica de eletroforese. O estudo de 14 loci gênicos revelou alelos diagnósticos e alelos exclusivos com uma baixa frequência. A heterozigosidade variou de 0,000 em H. albopunctatus a 0,199 em H. hermanni, a qual foi maior que a média para outras espécies de Hypostomus, como também para outros grupos de peixes já estudadas. Hypostomus albopunctatus e H. regani revelaram maior similaridade (I = 0,804), enquanto que H. hermanni e Hypostomus sp. 1/NUP 5612 mostraram a menor identidade genética (I = 0,569). Todas as populações foram geneticamente distintas apesar de apresentarem muitos alelos em comum. O teste de FST resultou em um valor de 0,671, indicando uma diferenciação significativa entre as populações. Hypostomus sp. 1/NUP 5612 foi geneticamente diferenciada das três congêneres pelos loci Adh-A e G3pdh-B e por apresentar alelos raros exclusivos em outros seis sistemas enzimáticos.

Genetic variability of Hypostomus (Teleostei, Loricariidae) from the Ribeirão Maringá, a stream of the upper Rio Paraná basin, Brazil

Hypostomus strigaticeps and two morphotypes of Hypostomus were collected from Ribeirão Maringá, a small tributary of the Rio Pirapó, an effluent of the upper Rio Paraná. The three populations were analyzed by allozyme electrophoresis that allowed the scoring of 25 loci from 14 enzyme systems. Heterozygosity values (He) were 0.028 in H. strigaticeps, 0.027 in Hypostomus sp. 1 and zero in Hypostomus sp. 2. Several diagnostic loci and fixed differences were observed for each population at loci Acp-A, Gcdh-A and Mdhp-A. Thus, all populations were genetically distinct, although there were many common alleles. The unbiased genetic identities of Nei (I) were estimated as 0.780 for Hypostomus sp. 1 and H. strigaticeps, 0.357 for H. strigaticeps and Hypostomus sp. 2 and 0.322 for Hypostomus sp. 1 and Hypostomus sp. 2. The data indicate that the two morphotypes are distinct species from Hypostomus strigaticeps.