Variabilidade genética de larvas e alevinos de piracanjuba (Brycon orbignyanus)

Abstract

RESUMO O objetivo do presente trabalho foi avaliar a variabilidade genética de larvas e alevinos de piracanjuba em programa de repovoamento. Foram coletadas 180 larvas de piracanjuba de três dias e 90 alevinos de três meses de idade. Foram avaliados cinco loci microssatélites, os quais produziram 19 alelos. Não houve presença de alelos raros nem perdas de alelos ao longo do período. A heterozigosidade observada foi superior nas larvas em relação aos alevinos. Houve desvio no equilíbrio de Hardy-Weinberg na maioria dos loci em ambos os grupos. O coeficiente de endogamia foi positivo em ambos os grupos, sendo a média dos alevinos superior em relação às larvas. O excesso de heterozigotos foi significativo no modelo Stepwise Mutation Model para os alevinos, indicando a possibilidade de efeito gargalo recente. Conclui-se que, apesar da adequada variabilidade genética encontrada, os valores do coeficiente de endogamia e a possibilidade de efeito gargalo nos alevinos atentam para a necessidade de constante monitoramento genético desses estoques antes da liberação no ambiente.

Spawning methods affect the reproductive efficiency of piracanjuba fish (Brycon orbignyanus) in restocking programs

“…orbignyanus (Castro et al, 2019). The absence of alleles exclusive to any of the groups suggests there was uniformity of contribution by breeders to progeny across treatments irrespective of the spawning method (Lopera-Barrero et al, 2014).…”

“…In semi-natural spawning, after second hormone administration, the breeders were housed in a circular tank with a forced-circulation water system designed to induce semi-natural spawning conditions. Post spawning (about six hours after pituitary injection) the eggs were collected via an outlet pipe at the center of the spawning tank and transferred to incubators (Castro et al 2019).…”

“…The number of breeders did not affect fertilization or hatching rates within spawning method. An improvement was expected, once the increase in the number of animals may compensate the reduction of the damage caused by the non-participation of animals in the reproductive process because they are not yet able to reproduce or have poor gamete quality (Castro et al, 2019).…”

“…orbignyanus, and injuries caused by stripping, such as loss of scales, which favors fungi and bacteria proliferation leading to animal death (Zanoni et al, 2019;Castro et al, 2019). Sato et al (1997) attributed 83.3% death of stripped breeders to lesions and hyperemia accompanied with secondary bacterial and fungal infections.…”

“…In stripspawning, after reproductive induction by hormonal application, oocytes and sperm are collected by abdominal pressure, mixed in the presence of water and fertilized eggs are incubated (Zaniboni-Filho and Nuñer, 2004;Reynalte-Tataje et al, 2013). In seminatural spawning, characterized by low interference by handlers (Lopera-Barrero et al, 2014), after reproductive induction, males and females are placed together in a customdesigned tank with re-circulation system simulating riverine flow that induces spontaneous spawning, and the eggs are collected by a pipe system that deposits them directly in the incubators (Zaniboni-Filho and Nuñer, 2004;Castro et al, 2019).…”