Status-dependent and strategic growth adjustments in female cooperative cichlids

摘要

Male group-living cichlids show status and strategic adjustments in growth, but females appear not to show these growth adjustments. Here, an experimental study in the Lake Tanganyika cichlid Neolamprologus pulcher elaborates on these findings. Females did not show status-dependent growth: (1) Growth in females decelerated with body size but did not depend on social status (breeder or helper), and (2) female helpers did not increase their growth rate after becoming a breeder. Females showed limited evidence for strategic growth: (3) Female helpers did not significantly adjust their growth rate depending on the treatments (comparing female helpers living in groups with a small or a large breeder female); but within the small breeder female treatment, helper growth was significantly related to their body size difference (breeder size–helper size), suggesting a strong non-linear effect of size differences on female helper growth. I conclude that these female cichlids show no status-dependent growth and only strategic growth adjustments when the size difference between the helper female and her breeder female is particularly small.