5. Conclusion
In summary, it was demonstrated that androgens are necessary
for the expression of reproductive behaviors but not for the expression
of aggressive behavior in male tilapia, suggesting a mediator
role in the former case and a moderator role in the later. Future
studies combining castration with the exogenous administration
of different androgens are needed to further explore the moderator
role of androgens on aggressive behavior in this species.
Acknowledgments
The authors thank Elsa Couto for running the radioimmunoassays
in the lab. This study was funded by the research Grants
PTDC/PSI/71811/2006 and PTDC/MAR/72117/2006 from Science
and Technology Foundation, Ministry of Education and Science
(FCT, Portugal; Grant holder: R. Oliveira), the European Commission
FEDER Program, and the FCT Pluriannual Program (R&D unit
MAR-LVT-Lisboa-331; Grant holder: R. Oliveira). During this project
O. Almeida was being supported by a Ph.D. fellowship from
FCT (SFRH/BD/37187/2007).