Reproductive investment in convict cichlids
My dissertation examined how male quality and female intrasexual competition affect maternal investment patterns and defensive behavior in the convict cichlid (Amatitlania siquia), a biparental freshwater fish. Intersexual and intrasexual interactions have typically been investigated in isolation from one another, but their combined effects influence the social dynamics that affect mating and parental investment strategies.
Intersexual dynamics
Using a combined field and laboratory approach, I found that male quality influenced maternal reproductive investment, with females providing more parental care to the offspring of higher quality males. However, females did not increase their fecundity when paired with higher quality males, which limited the costs associated with increased investment and prevented trade-offs in reproduction in a subsequent breeding event. The increased maternal investment may stabilize the pair-bond between the parents, which ultimately increases female reproductive success.
Using a combined field and laboratory approach, I found that male quality influenced maternal reproductive investment, with females providing more parental care to the offspring of higher quality males. However, females did not increase their fecundity when paired with higher quality males, which limited the costs associated with increased investment and prevented trade-offs in reproduction in a subsequent breeding event. The increased maternal investment may stabilize the pair-bond between the parents, which ultimately increases female reproductive success.
Female convict cichlid guarding eggs (small dots on back of pot) during controlled breeding experiment
Intrasexual female competition
I examined the role of female intrasexual competition in a natural population in Costa Rica where sexually-receptive females advertise their reproductive status using bright ornamentation. These females actively compete for access to already paired males, and thus pose a threat to the parental female’s mating status. I found that both parents responded aggressively to these females and that differences in partner quality modulated the response to ornamented females. The joint defense of the pair-bond suggests that when biparental care is necessary to ensure offspring survival reproductive success for both sexes may be maximized by cooperation, rather than conflict.
I examined the role of female intrasexual competition in a natural population in Costa Rica where sexually-receptive females advertise their reproductive status using bright ornamentation. These females actively compete for access to already paired males, and thus pose a threat to the parental female’s mating status. I found that both parents responded aggressively to these females and that differences in partner quality modulated the response to ornamented females. The joint defense of the pair-bond suggests that when biparental care is necessary to ensure offspring survival reproductive success for both sexes may be maximized by cooperation, rather than conflict.
The video above shows the aggressive interactions between females. In the front of the video is an unmated female, which has the neon flecks along her fins that indicate her reproductive status, in the middle is the large male, and in the back is the female that is currently mated to the male and guarding his offspring. Both parents behave aggressively toward the unmated female, but by the end of the day the male had abandoned his partner and their young and about a week later we found him paired with the new female guarding young.