Predation environment affects boldness temperament of neotropical livebearers


behavioral syndromes, Brachyrhaphis rhabdophora, Poeciliidae


Behavioral traits of individuals are important phenotypes that potentially interact with many other traits, an understanding of which may illuminate the evolutionary forces affecting populations and species. Among the five axes of temperament is the propensity to behave boldly in the presence of a perceived risk. To determine the effect of different predatorial regimes on boldness and fearfulness, we assessed the behavior of individuals in a novel portable swim chamber (i.e., forced open-field test) by Brachyrhaphis rhabdophora (n = 633). We used an information theoretic framework to compare generalized (logistic) linear fixed-effects models of predatorial regime (predator-free [n = 6] and predator [n = 4] sites), sex, and standard length (SL). Fish from predator sites were much more fearful in the novel arena than fish from nonpredator sites. This varied by length, but not by sex. At 48 mm SL, fish from nonpredator sites were 4.9 times more likely to express bold behavior (ambulation) in the novel swim chamber as fish from predator sites. Probabilities of “ambulating” within the swim chamber increased with size for nonpredator sites and decreased with size for predator sites.

Original Publication Citation

Rasmussen, J.E., and M.C.Belk. 2017. Predation environment affects boldness temperament of neotropical livebearers. Ecology and Evolution 7: 3059-3066.

Document Type

Peer-Reviewed Article

Publication Date


Permanent URL


Ecology and Evolution




Life Sciences



University Standing at Time of Publication

Full Professor