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Behavioral counter-strategies against infanticide in corn mouse females, Calomys musculinus

2011; SAREM; Volume: 18; Issue: 2 Linguagem: Inglês

1666-0536

José Coda, José Priotto, Andrea R. Steinmann,

Rabbits: Nutrition, Reproduction, Health

Based on the hypothesis that in C. musculinus both female territorial behavior and promiscuity are counter-strategies against infanticide by females and males respectively, our objective was to test the following predictions: (1) mother aggression deters infanticide by females; (2) previous matings prevent infanticide by males. We conducted 116 behavioral encounters between mothers and intruders to study the nest related behaviors. Mother-pups units (Mu) were grouped in three treatments in relation to the intruder feature: 55 Mu were placed with siring males, 27 Mu and 34 Mu were housed with non-siring males and repro- ductively active females, respectively. We also calculated offspring survival rate for each treatment. The nest related behaviors varied among the three groups tested. Mothers showed high rates of aggressive behavior towards females. In presence of siring males mothers remained calm inside the nest. When the intruders were non-siring males mothers exhibited high rates of nest defense behavior. The lowest survival rate was registered in presence of the non-siring males, while the highest rates were registered in presence of females or siring males. The absence of aggressiveness and the high rate of nest defense by mothers against siring and non-siring males respectively, would support that promiscuity acts as a counter-strategy against infanticide by males. Mother aggressive behavior against intruder females would show that female territoriality may be an effective way of pup protection. RESUMEN: Contraestrategias comportamentales contra el infanticidio en hembras de C. musculinus. Bajo la hipotesis de que la territorialidad intra-sexual y el apareamiento multiple por parte de las hembras de C. musculinus actuan como contra-estrategias para evitar el infanticidio cometido por hembras y machos respectivamente, nuestro objetivo fue probar las siguientes predicciones: 1) la agresion de la madre impide el infanticidio por hembras, 2) los apareamientos previos previenen el infanticidio por parte de machos. Estudiamos comportamientos relacionados al nido en 116 unidades madre-cria (Mc) agrupadas en tres tratamientos en relacion a las caracteristicas del intruso: 55 Mc alojadas con los padres de las crias; 27 Mc y 34 Mc alojadas con machos sin experiencia sexual con la madre y con hembras reproductivas, respectivamente. En cada tratamiento se calcularon las tasas de sobrevida Las madres fueron agresivas hacia las hembras. En presencia de los padres las madres permanecieron tranquilas en sus nidos. La menor tasa de sobrevida se registro en presencia del macho no padre; las mayores en presencia del padre y hembras repro- ductivas. La ausencia de agresividad y las altas tasas de defensa del nido exhibidas por las madres hacia los padres y los machos extranos respectivamente, apoyan la hipotesis que propone la promiscuidad como contraestrategia al infanticidio por machos. La respuesta altamente agresiva de las madres hacia las hembras intrusas seria una estrategia efectiva para la proteccion de sus crias.