Biological Sciences, School of


First Advisor

Alexandra L. Basolo

Date of this Version



DiSciullo, R.A. 2016. Inter- and intra-individual variation in predator-related behavioral plasticity expressed by female green swordtails (Xiphophorus hellerii). MS Thesis, University of Nebraska-Lincoln


A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Biological Sciences, Under the Supervision of Professor Alexandra L. Basolo. Lincoln, Nebraska: November, 2016

Copyright © 2016 Rachael A. DiSciullo


Phenotypic plasticity is the ability of one genotype to express multiple phenotypes under variable environments. Behavioral plasticity is a type of phenotypic plasticity in which individuals adjust behavior in response to changes in environment. Often, behavioral plasticity is studied at the level of the population, rather than at the level of the individual. Further, few studies have considered the effect of individual traits, such as size and age, on the expression of behavioral plasticity, or, how individual plasticity may be correlated across different contexts. In this study, we used female green swordtails (Xiphophorus hellerii) to test the effects of body size at testing and age at maturation on the expression of predator-related behavioral plasticity in two social contexts: (1) intrasexual (two females) and (2) intersexual (two females and a male). We also tested the extent to which plasticity is correlated across contexts within individuals, to elucidate whether females that show a high degree of plasticity in one context also show a high degree of plasticity in another context. For two agonistic behaviors, we found differing effects of the interaction of body size at testing and age at maturation on the expression of predator-related plasticity across social contexts. These results suggest that individual traits interact in a complex manner to affect patterns of plasticity across contexts, and, that alleles influencing age at maturation may be associated with alleles that affect plasticity. Across contexts, we found no evidence of correlated plasticity in a given behavior, suggesting that individuals are not consistently plastic across the contexts tested. Within contexts, however, the plasticity expression for several different behaviors was correlated, and was similarly affected by body size at testing and age at maturation. Overall, this study indicates that the type and degree of individual predator-related behavioral plasticity expressed is partially dependent on multiple traits, and varies substantially between social contexts. Few studies have examined the effect of multiple factors on the expression of plasticity, or plasticity in multiple social contexts, and, our results indicate that the causes and consequences of phenotypic plasticity are likely to be complex.

Advisor: Alexandra L. Basolo