Investigation of androgen receptor gene expression in response to predator and male densities in Guppy fish (Poecilia reticulata)

Document Type : Research Paper

Authors

1 Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran.

2 Department of Fisheries, Baharavaran Faculty of Agricultural, University of Applied Science, Qom, Iran.

10.22059/jfisheries.2025.393071.1454

Abstract

The guppy fish (Poecilia reticulata) is widely recognized as a model species for studying the evolution of reproductive behavior due to its broad range of mating strategies and the availability of genomic and genetic resources. Androgens, as key regulators of spermatogenesis, exert their effects by binding to the Androgen receptor (AR), which plays a critical role in the regulation of reproductive function. Given the importance of this hormonal pathway, the present study aimed to investigate the expression of the androgen receptor gene in response to varying densities of predators and male guppies. Male and female guppies were sampled at four time points: 5 minutes, 5 hours, 5 days, and 15 days after exposure to a predator. Samples were immediately frozen in liquid nitrogen and stored at –80°C until RNA extraction. AR gene expression was analyzed using the reference gene S18 and quantified by the 2^(-∆∆Ct) method. Data normality was assessed, and a two-way ANOVA was performed to determine the statistical significance of treatment effects. Results indicated that predator density had a significant effect on AR gene expression across different time points (P<0.05). Specifically, the presence of predators led to a downregulation of AR gene expression, which is likely associated with reduced reproductive behavior in male guppies. These findings provide valuable insights into how environmental pressures, such as predator and conspecific density, can influence hormonal regulation of reproduction in this model species.

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Main Subjects

References

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Journal of Fisheries
Volume 78, Issue 2
July 2025
Pages 149-158

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