Genetic and morphometric analysis of three species of the genus Hypostomus Lacépède, 1803 (Osteichthyes: Loricariidae) from the Rio Iguaçu basin (Brazil)

Abstract

Three species of Hypostomus from the Rio Iguaçu basin, H. aff. commersonii, H. derbyi and H. myersi, were examinated by multivariate analysis, PCA and size-free discriminant canonical analysis, by the external characters truss network method and starch gel isoenzyme electrophoresis in heart, liver and muscle tissues. Twenty-six gene loci of 14 isoenzyme systems (AAT, ACP, ADH, GDH, G3PDH, G6PDH, GPI, IDHP, LDH, MDH, ME, PGM, PER and SOD) were scored for the first time for these species. The percentage of polymorphic: loci (P0.99) varied from 11.54% for H. derbyi and H. myersi to 19.23% in H. aff. commersonii. Expected mean heterozygosity (He) varied from 0.011 in H. derbyi to 0.044 in H. aff. commersonii. Nei's genetic distance (D) between H. aff. commersonii and H. derbyi was 0.142, between H. aff. commersonii and H. myersi 0.621, and between H. derbyi and H. myersi 0.776. We discuss hypotheses for the maintenance of the low mean heterozygosity observed, and for the presence of these species in this drainage basin.