Neolamprologus pulcher is a cooperatively breeding cichlid fish, in which helpers stay in their natal territory and help with brood care, territory defense, and maintenance. In this study we investigated helper effects by an experimental group size reduction in the field. After this...

Cooperatively breeding animals, in which helpers may participate in reproduction with dominant breeders, are ideal species for examining intraspecific variation in testis size because they often exhibit both monogamous breeding (low risk of sperm competition) and polyandrous breeding (high risk)...