Correlating context-specific boldness and physiological condition of female sand fiddler crabs (Uca pugilator)

Abstract

Consistent individual behavioral differences across ecological contexts are a recognized feature of animal populations. These differences can be expressed in two ways: context-specifically or context-generally. The former is characterized by consistent responses in one context (i.e. repeatability), whereas the latter by consistency that spans contexts (i.e. behavioral syndromes). The proximate causes of behavioral consistency remain unclear, yet there is evidence that physiology may couple the expression of some behavioral traits in unrelated contexts. We therefore explored the correlation between bold behavior of female sand fiddler crabs (Uca pugilator) and the condition of the hepatopancreas, an organ vital to crustacean metabolism and reproduction. We did this by taking replicate measurements of two risk-taking behaviors per individual in the contexts of predator avoidance and environment exploration, and examining correlations within and between these observations. We then determined the relationship of behavior with hepatopancreas mass and lipid content. Individual crabs responded consistently within each context. However, across-context correlations were absent, indicating that boldness is isolated, at least in the selected scenarios. Additionally, anti-predator and exploratory behaviors were significantly influenced by size but not linked to hepatopancreas physiology. Our results show that context-specific trait expression may occur in the absence of a physiological correlate.