Behaviour 2019
Correlated behaviors and a melanin-based signal of aggression in females of a livebearing fish
Gita R Kolluru1, Yasmine J Akky1, Ryan L Earley2. 1California Polytechnic State University, San Luis Obispo, CA, United States; 2California Polytechnic State University, San Luis Obispo, CA, United States; 3University of Alabama, Tuscaloosa, AL, United States

Behavioral traits may be correlated with each other and with other phenotypic traits, including coloration. However, rarely do studies of such relationships and their adaptive significance focus on females. We describe relationships among behavior, morphology and reproductive output across mating, foraging and risk contexts in females of the livebearing fish, Girardinus metallicus. Females were aggressive to each other and to males, and aggression was signaled by the darkening of a dynamic dorsal fin black spot and by fin flaring behavior. Spot darkening was positively correlated with aggression and negatively correlated with following males, suggesting that it honestly indicates motivational state. Smaller females were less aggressive to females and males, received more courtship and had more offspring, consistent with a trade-off between aggression and mating activity. In contrast to studies of males, we found a negative relationship between boldness and aggression, consistent either with a tradeoff or with selection directly favoring the negative relationship. Our results highlight the importance of studying trait integration in females outside of a mate choice context alone.