Journal of Natural Environment

Investigation of Melanocortin-4 receptor gene expression in response to variations in predator density and male density in Guppy (Poecilia reticulata )

Document Type : Research Paper

Authors

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

2 Department of Fisheries, Baharavaran Faculty of Agriculture, University of Applied Science and Technology, Qom Province, Qom, Iran.

10.22059/jne.2025.392154.2786

Abstract

The guppy, due to its diverse reproductive behaviors and extensive genetic resources, is considered a suitable model for studying the evolution of reproductive behaviors. The melanocortin-4 receptor (MC4R) plays a role in regulating energy balance, stress response, and reproductive control in vertebrates. This study examined the effect of different predator densities and the presence of competing males on MC4R gene expression in guppy. Experiments were conducted under controlled conditions in six treatments with different predator numbers and male densities. Sampling was performed at four time points: 5 minutes, 5 hours, 5 days, and 15 days after exposure. The relative expression of the MC4R gene was evaluated using Real-Time PCR and compared with the reference gene 18s. The results showed that predator density and the presence of competing males had a significant effect on MC4R gene expression in guppy (P<0.05). The highest gene expression was observed in treatments with predators and high male density, 5 hours after exposure; however, with prolonged exposure, gene expression decreased. These results indicate that MC4R is a key regulator in biological processes such as growth, reproduction, stress responses, and metabolic rate. The findings also confirm the relationship of this gene with the regulation of reproductive behaviors and adaptation to predators and sexual competition. It is suggested that future studies examine the signaling mechanisms of MC4R and its epigenetic changes under long-term exposure to stress factors to determine its precise role in regulating physiological and behavioral responses.

Keywords

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Journal of Natural Environment
Volume 77, Issue 4
March 2025
Pages 591-599