Morfologia e aspectos reprodutivos em uma população isolada de Psalidodon aff. fasciatus no Parque Estadual Vila Velha, Paraná, Brasil.

Abstract

Inbreeding decreases intrapopulational genetic variability, increasing the frequency of deleterious alleles that are normally expressed only in recessive homozygosis. Consequently, inbreeding populations, especially when small and isolated, may suffer negative influences on the adaptive value and vulnerability to extinction. In natural populations, due to physiological and behavioral mechanisms, inbreeding is expected to be avoided. However, the organisms studied in this work, characterize a small population of neotropical fish (Psalidodon aff. fasciatus), popularly known as lambaris, that live a natural environment with a rare geological configuration, in the shaped of well (Furna 2 Vila Velha State Park) reflecting in an intra and interspecific isolation, therefore, inbreeding cannot be avoided among these fish. This way, the objective of this work was to investigate the effects of population isolation, considering morphological and reproductive aspects of the species. To this, morphometric analyzes were applied on digital radiographs in order that investigate congenital malformations. Also, histological analysis of organs reproductive organs was carried out to characterize the stages of gonadal development. Not only, sex ratio, weight-length relationship and relative condition factor (Kn) were determined. The results indicate fish with spinal deformities, including wide variation in the number of caudal vertebrae and corporal deformations related to a flattened body and spinal curvature, reflecting the absence of gene flow and inbreeding in this population. A potential model into Evo-Devo studies. The sexual proportion showed a significant predominance of males (1M: 0,6 F). The total weight and total length relationship was WT = 0.0002 LT 2.3039, showing a negative allometric growth, indicating a greater allocation of energy in length than in weight. Welfare index was determined individually. No significant difference was observed between the sexes, both had a mean value of Kn = 0.95. Five stages of gonadal development were characterized being resting, initial ripe, mature, partially spent, totally spent, similar to the other lambaris. The results obtained suggest that the natural isolation is being reflected in inbreeding effects, sensitively perceived by the occurrence of congenital malformations, and this may have implications for the adaptive value of the population.