INVESTIGADORES
SCAIA Maria Florencia
congresos y reuniones científicas
Título:
Fighting cichlids: the role of estradiol and testosterone in male and female aggression
Autor/es:
MARÍA FLORENCIA SCAIA
Lugar:
Woods Hole
Reunión:
Simposio; 20th Annual FIR symposium, MBL; 2017
Institución organizadora:
Marine Biological Laboratory
Resumen:
Aggression in vertebrates is one of the areas of growing interest among social and reproductive behaviors and mechanisms involved in its regulation include physiological, genetic and social factors. This behavior has been well studied in males competing for resources, but female aggression is still understudied. Androgen regulation is one of the most studied physiological mechanisms in male aggression, but there is growing evidence regarding the importance of aromatization in brain and suggesting a possible role of estradiol (E2). Cichlasoma dimerus is a serially monogamous Neotropical cichlid fish with hierarchical social systems in which both reproductive male and female dominants defend their status with aggressive displays towards other subordinate, non-reproductive fish. The aim of my current research is to analyze male and female aggression in dyadic agonistic encounters, and to study the role of testosterone (T), E2 and aromatase enzyme regulating this behavior. To achieve this goal, agonistic encounters between sex-paired fish were held during one hour, and behavior was recorded and analyzed during this period. Moreover, plasma was collected before and immediately after each contest, and samples were processed for hormonal determinations by ELISA. In both sexes, aggressive displays included chases, bites, approaches and mouth fighting, while submissive behavior included escapes and passive coping. In most contests three phases could be clearly distinguished: pre-conflict, conflict (both animals display aggressive and submissive behaviors, resulting in a winner/loser), post-conflict (the winner maintains its status and central location in the aquaria with occasional aggressive displays). As regards sexual steroids, female winners have higher plasma E2 than losers (p=0,0457) and there are no differences in plasma T. This is not the case for males, since there were no differences in E2 or T between winners and losers (p=0,8548 and p=0,1405, respectively). Moreover, plasma T levels in males significantly increase after agonistic encounters (p=0,0107), and E2 shows the same trend at least in ten from twelve analyzed males. These results suggest that the Challenge Hypothesis is proved in males from this species, and that a similar hypothesis could be suggested for E2 for the first time. In summary, the results presented here support the hypothesis that the role of both androgens and estrogens may vary with the stability of social environment. Moreover, these results also suggest that estrogens could be involved in regulating female aggression, and this encourages us to continue studying the role of brain aromatase in this mechanism.